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By Will H. Coghill, I. L. Feld, G. D. Coe

The object of this paper . is to make known the superior classification accomplished in a hydraulic classifier designed to make use of principles determined by recent research ... The details of the design , the results of preliminary research , and the final testing are given . The classifier of the new design shown in figure 1 and another one like it are in operation as concentration classifiers in a Birmingham iron- ore mill recovering 4 tons per hour of concentrates from table middling that ` otherwise would require regrinding and retabling . The four factors that contribute to the successful operation of these classifiers are ( 1 ) a teeter column of small diameter , ( 2 ) use of an open - bottom tooter column classifier with a periodic pincer instead of the usual type , which terminates in a vortex, ( 3 ) a sorting chamber under separate hydraulic control , and ( 4 ) a teeter column of more than the usual depth . · At the outset it must be stated positively what the authors mean by hydraulic classification : They mean the reconstruction of a multimineral ground product into fractions graded with respect to size , so that cach fraction has the heavy mineral segregated in the fine sizes and the light mineral segregated in the coarse sizes . This definition presupposes that in multiplespigot classification the low specific gravity minerals are carried beyond the first cells to the later ones . The reader must take into account that , from the standpoint of classification , " ores " may be divided into two types , represented - by the following : ( 1 ) Joplin flint - blende ores , which , because of the hardness of the flint and the softness of the blonde , yield upon comminution a product that already has the essence of classification ; and ( 2 ) Birmingham Big Seam iron oros , which contain " easily shelled - out " sca sand and , upon reduction to about 10 mesh , yield a heterogeneous mixture in which the size analyses of the respective " floats " and " sinks " arc almost identical .

Dec 1, 1945

By Pablo Velasco

Ecuador had limited mineral output, al-though the Government attempted to stimulate metallic mineral exploration and also evaluated a gypsum and a phosphate deposit. A pilot plant to exploit gold deposits was established, and there was extensive gold exploration activity in southern Ecuador. Domestic output of iron and steel declined sharply. Among all minerals, petroleum output was the dominant factor with both exports and production increasing significantly over that of 1988. Crude oil exports contributed 63% of total export earnings and about 70% of the central Government's revenue.

Jan 1, 1986

By Richard C. Ballance

Fly ash from four sources and in certain proportions was shown to assist chemical coagulation of turbid water and settling of chemically induced floc. Fly ash reduced the time required to form the first visible floc, promoted more uniform flocs about 2 mm in diameter, and increased the mean settling rate of floc particles. Also, the addition of fly ash produced denser sludges than those obtained with alum alone. Final turbidities were independent of fly ash particle size and carbon content. Optimum proportions of fly ash additive are given.

Jan 1, 1966

By R. E. Meaker

Electrical conductivities and densities of molten fluoride systems were measured as functions of the melt temperature and composition. For any given mixture, the two properties change linearly with temperature. Three alkali metal fluorides were selected as solvents for melts of the type LiF-, NaF-, and KF-MFx, where M is a metal selected from the alkali metal or alkaline earth groups, or from the lanthanide or actinide series of elements, and x = 1-4. Heats of activation for conductance were calculated from the experimental data and varied from 2.3 to 9.2 kcal/mole at 1,000° C. Some relation between position in the phase diagram and the conductivity changes was suggested.

Jan 1, 1971

By G. E. Walden

The Bureau of Mines is currently engaged in a continuing investigation of the thermodynamic properties of certain inorganic compounds. As a part of this investigation, the heat contents of bismuth and cerous chlorides were measured throughout the temperature ranges of 370° to 630° K. and 370° to 1,200° K., respectively. Equations representing heat contents as a function of temperature were derived from the data by the method of least squares. These equations were used to calculate heat contents at selected temperature intervals ranging from the ice point to 650° K. for bismuth chloride and to 1,200° K. for cerous chloride; also, the heats of fusion of both compounds were calculated at their respective melting points. EXPERIMENTAL Materials The cerous chloride used in this investigation was supplied by the National Carbon Company of Cleveland, Ohio. A chemical analysis indicated Ce 56.57 percent and Cl 43.39 percent. No attempt was made to purify the compound or identify impurities since the analysis showed only about 0.04 percent total impurities. Reagent grade bismuth chloride was used without additional purification.

Jan 1, 1961

By George H. Johnson

An evaluation of the diamond-bit-performance data accumulated from core-drilling cherty limestone and cherty dolomite reveals that the percentage of core recovered and the physical characteristics of the bits and diamonds used are economically significant. One of the established trends, of particular interest to those engaged in diamond drilling, is that bits set with small, low-quality, West African drill bort are the most economical. Detailed analysis of the factors that affect diamond-bit performances, such as diamond size and quality, bit size and type, percentage of core recovered, and the physical characteristics of the bit matrices are assessed in the tables, charts, and discussion.

Jan 1, 1958

By Richard J. Mainiero, Michael J. Sapko, Marcia L. Harris

Since 1988, there have been 17 documented incidents in the United States and Canada in which carbon monoxide (CO) is suspected to have migrated through ground strata into occupied enclosed spaces as a result of proximate trench blasting or surface mine blasting. These incidents resulted in 39 suspected or medically verified carbon monoxide poisonings and one fatality. To better understand the factors contributing to this hazard, the National Institute for Occupational Safety and Health (NIOSH) carried out studies in a 12-foot diameter sphere to identify key factors that may enhance the levels of CO associated with the detonation of several commercial trenching explosives. The gaseous detonation products from emulsions, a watergel, and ANFO blasting agents as well as gelatin dynamite, TNT, and Pentolite boosters were measured in an argon atmosphere and compared with those for the same explosives detonated in air. Test variables included explosive formulation, wrapper, aluminum addition, oxygen balance, and density. Major contributing factors to CO production, under these laboratory test conditions, are presented. The main finding is the high CO production associated with the lack of afterburning in an oxygen poor atmosphere. Fumes measurements are compared with the manufacturer’s reported IME fume class and with the Federal Relative Toxicity Standard 30 CFR Part 15 in order to gain an understanding of the relative toxicity of some explosives used in trench blasting.

Lower the respirable dust expo? sure of longwall shearer operators Approach Use improved water sprays on the shearer machine to direct the dusty air toward the face. In laboratory tests and actual mining conditions, the shearer-clearer has proved to be an effective dust control technique. Recent field experience however, has indicated that not enough technical information is available on proper installation of the improved shearer-clearer. This Technology News will provide details of the Improvements made to the shearer-clearer and provide guidelines for installing the system. How It Works The shearer-clearer system consists of several strategically-mounted water sprays and one or more passive barriers. The sprays redirect the airflow around the shearer into both a clean and a contaminated split. The sprays confine the contaminated split or dust cloud to the coal face, allowing the shearer operators to remain in the clean split on the walkway

Jan 1, 1986

By Thomas E. Green

A solvent extraction procedure using 8-hydroxyquinoline and chloroform was investigated by the Bureau of Mines as a preconcentration technique for the determination of aluminum, calcium, cobalt, copper, iron, lead, magnesium, manganese, nickel, and zinc in large samples of high purity tungsten. X-ray spectrographic and atomic absorption methods were used to determine the trace metals after preconcentration. The presence of 10 grams of tungsten had a pronounced effect on the distribution of 8-hydroxyquinoline between the aqueous and chloroform phases. This change in the 8-hydroxyquinoline distribution in turn had an adverse effect on the extraction of the trace metals. Extraction efficiencies can also be adversely affected by an increase in the quantity of extractable metals present, as shown by radiotracer tests using 65Zn. Excess 8-hydroxyquinoline in the extracts did not interfere with the determination -of the serious interference in the combined ion exchange paper--X-ray spectrographic method. Although preconcentration by 8-hydroxyquinoline extraction was found to be partially successful, other preconcentrationn methods based on ion exchange and dithizone extraction were found to be superior.

Jan 1, 1968

By T. F. Dumm, O. Trass, V. R. Koka, L. G. Austin

"The size distributions of carefully screened 2 size fractions of ground materials were determined using a Microtrac laser dif-fractometer. The size distributions were fitted to the empirical function P(x) = 1/[1 + (x50/x)1] where P(x) is cumulative mass fraction less than Microtrac size, x. The standard deviation of A for a 50 second test time was approximately 0.5, so that seventeen test times give a mean with an estimated error within t 0.25 (95% confidence level). Values of were 5.44, 4.82, 4.40 for a coal ground under different conditions, indicating statistically different shape distributions; the average value for mica was 2.91 owing to the high aspect ratio of the particles. The ratio of x50 to the geometric mean sieve size was 1.2 for the coal and 0.70 for mica.1 IntroductionKoka and Trass have presented evidence [1,2] that materials ground in the Szego mill [3] give different shapes depending on the milling conditions. The variations in shape were deduced qualitatively by viewing SEM photomicrographs of selected 1/2 screen fractions. This paper quantifies their observed differences in shape by using measurements of the size distributions of screen fractions examined in a laser diffractometer [4] (Microtrac, Model 7991). The basic concept is that particles of 'a given ""screen"" size will give a wider distribution of ""Microtrac"" size when the particles are flaky with high aspect ratios, and a narrower distribution when the particles approach the cubical and spherical geometries.2 TheoryAustin and Shah [5] have shown that coal screened within a 1. 1/2 upper-to-lower sieve size range will give rise to a much wider distribution of Microtrac size. They found that the screen interval of irregular fragments of comminuted coals or quartz gave Microtrac size distributions which could be described by the simple function"

Jan 1, 1988

By Elizabeth A. Johnson

The effect of slag composition on lead losses to slags and on the behavior of associated accessory elements in lead blast furnace smelting has been studied by the Bureau of Mines. Equilibrations of 30 g of lead and synthetic slag doped with Cu, In, TI, and Sb at 1,200° C in CO-C02 atmospheres revealed the importance of the FeO:Si02 ratio and the basicity ratio, (CaO+MgO):SiO2, of the slag. Lead losses to slags increased with an increasing FeO:Si02 ratio and decreased with an in-creasing basicity ratio. Copper and indium distribution coefficients, [Lx =] increased from 15 at the lower basicity ratios to near 60 at higher basicity ratios. LTI values increased from 20 to 150 as slag basicity increased. Lcu, Lin, and LTI were relatively in-dependent of the FeO:Si02 ratio, but increased with greater amounts of accessory elements in the system. Antimony distribution alone was shown to be strongly affected by FeO:Si02 ratio, although data were scattered. LSb values ranged from 20 to 800 and decreased sharply with increasing FeO:Si02 ratios. The basicity ratio and the level of accessory element load did not have any noticeable effect on LSb.

Jan 1, 1983

By James A. Wasson

This Bureau of Mines report summarizes the application of pilot flooding in the evaluation of a potential waterflood project. Aspects of pilot flooding discussed include choice of pilot location, confined and unconfined waterfloods, operational precautions, and comparison of predicted with observed performance. Summaries of published methods of pilot flood data analysis for determination of full-scale waterflood feasibility are presented and their use illustrated for example pilot flood data.

Jan 1, 1974

By Earl L. Hastings

Although the principal market for diatomite in the United States is in the East,4 production of the material is presently restricted to the West, because the deposits are larger, mining costs are cheaper, and the quality of product is better than that obtained from other domestic deposits. However, Tallahatta diatomite, occurring in Choctaw and Clarke Counties, Ala., has a freight rate advantage, which should encourage competition for those market that are now being supplied with the purer diatomites from the western deposits. For this reason, diatomite occurrences in the Tallahatta formation were examined by the Bureau of Mines and physical properties of samples from the deposit were determined to obtain additional data for use by any potential producer who wished to evaluate the material for its commercial possibilities. In 1894 K. M. Cunningham5 found that the buhrstone formation (now known as the Tallahatta formation) contained "siliceous shells of marine diatoms, radiolaria and foraminifera, thus being rather of the nature of tripoli or diatomaceous earth than of a true clay." Cooke6 and Semmes7 also reported the Tallahatta formation to be composed principally of diatomaceous earth with accompanying beds of sand, clay, and sandstone.

Jan 1, 1963

By H. B. Brunot

A complete list of permissible mine equipment, tested and approved by the Bureau of Mines previous to January 1, 1947, was published as Information Circular 7432.2/ A list of permissible mine equipment tested and approved by the Bureau of Mines during the calendar years 1947, 1948, and 1949 was published as Information Circular 7569. The present list supplements Information Circulars 7432 and 7569 and includes all of 'the equipment approved during the calendar year 1950. Information Circular 7465, which included a list of permissible mine equipment tested and approved by the Bureau of Mines during the calendar year 1947 therefore is superseded.

Jan 1, 1951

By F. C. Gregory

"The ""safety bonus"" in metal mining is a sum in addition to the regular wage, paid to foremen or bosses for keeping the accident rate down to a specified minimum. It has been used with success for some time by certain companies as a regular part of their safety work. It is desirable from the employer's point of view in that the desired results in accident reduction must be accomplished before the bonus is earned; and from the standpoint of the recipient, in that he receives a reward for the additional effort which he has put forth in order to earn the bonus.While this paper relates to the safety bonus as applied in the metal mining industry, the bonus system discussed herein will apply equal well to coal mining, oil-field work, and other mineral industries.Various estimates have been made as to the percentage of accidents that can be prevented through physical safeguards, adoption of safe working methods, and other safety measures which can be initiated and carried out wholly through the management or the safety department. This percentage will always be a vari¬able according to the local plant and conditions. But all who have been engaged in accident prevention agree that such work alone cannot bring the accident fre¬quency down to where it should be, and that it is very necessary to work directly with the workmen, in an effort to make each individual do his share in making the work safe. In this latter phase of the work, the boss who has immediate super¬vision of the men is the one who can do the most, since he is in daily and frequent contact with the men while they are at work. In the metal mines, the shift and stope bosses are the key men; in the oil fields, the ""tool-pushers"" or sub-foremen, and the same applies to all industries. So it becomes necessary to keep these sub-foremen constantly interested in accident prevention, both because they are in personal touch with the men and because they are responsible for production and hostile to any plan which they think will interfere with their output. In large organizations it is the shift boss who represents the company and its policies to the man on the job."

Jun 1, 1924

By N. E. Hanna

To be approved for use in underground coal mines in the United States, explosives and blasting devices must pass certain safety tests prescribed by the Federal Bureau of Mines. These tests are described in Schedule 1-G4/ (explosives) and Schedule 26A5/ (blasting devices). An explosive or blasting device that passes the appropriate tests is placed on the active permissible list. As this list is subject to continuous revision, it has been the practice of the Bureau of Mines to publish periodically the names of explosives and blasting devices that have been added to the active list, as well as those that have been transferred to the inactive list; changes in brand names also are reported. The present circular gives all explosives and blasting devices on the active permissible list as of December 31, 1957, and shows all changes, additions, and transfers in that list between December 31, 1951,6/ and December 31, 1957.

Jan 1, 1958

By E. C. Lane

This paper is the second report of the results of the United States Bureau of Mines twenty-third semiannual survey of motor fuel marketed in the United States. The first paper, reporting data relating to gravity, vapor pressure, and distillation range of the samples, was published as Report of Investigations 31293. A third and concluding paper giving the results of other tests will be published as soon as these tests have been completed. The present paper deals with the data of the twenty-third semiannual survey presented in accordance with the revised specifications for United States Government motor gasoline. The sample numbers used are identical with those used in Report of Investigations 3129, with additional data included for copper strip corrosion (method 530.22).4 and sulphur content by the lamp method.5 Three hundred and twelve samples were collected and analyzed in this survey. Two hundred and seven samples were competitive-price gasolines and one hundred and five samples were premium-price motor fuels.6

Jan 1, 1931

By A. F. Colombo, R. T. Sorensen, D. W. Frommer

The Bureau of Mines developed a flotation method for concentrating spiral tailing produced from pilot plant tests on the Champion mine ore fines . The feed material contained about 49 percent Fe and 15 percent SiO2 and was posed mostly of specular hematite , muscovite , and chlorite . Bench- scale , batch flotation research developed a reagent suite composed of tall oil - fatty acid , fuel oil , sulfuric acid , sodium fluoride , and sodium silicate for recovery of iron minerals in the froth product . Concentrate made with the reagent suite contained 87.3 percent of the iron and analyzed 65.6 percent Fe and 1.9 percent SiO2 . Continuous flotation tests were made with a nominal feed rate of 400 lb /hr , but without middling recirculation . Using nearly the same amount and complement of reagents as in the batch tests , three similar continuous tests gave concentrates averaging 63.9 percent Fe and 3.1 percent Sio while recovering about 86 percent of the iron .

Jan 1, 1964

By W. W. Weller

Low-temperature heat capacity measurements were conducted, and entropies at 298.15° K were evaluated for sodium monomolybdate (Na2Mo04), magnesium monomolybdate (MgMo04), and calcium monomolybdate (CaMo04). The 298.15° K entropy values were sodium monomolybdate, 38.1±0.3 cal/deg mole, magnesium monomolybdate, 28.4±0.2 cal/deg mole, and calcium monomolybdate, 29.3±0.2 cal/deg mole.

Jan 1, 1963

By X. Shi, N. S. Dala, V. Vallaythan

"Cellular damage induced by silica dust is known to be associated with increased fragility and destabilization or destruction of the cell membranes. The mechanism by which silica dust effects biological membranes is still unknown. Using the ESR spin-trap methodology, we find that hydroxyl radicals are generated in aqueous suspensions of freshly ground silica. The amount of the radicals generated depends on the extent of grinding and ""freshness"" of the dust. Using linoleic acid as a model lipid, we show that the silica dust causes lipid peroxidation via ·OH, 02-, or linoleic acid related radicals as intermediates. Catalase and superoxide dismutase inhibit the formation of these radicals. The results suggest that free radicals associated with freshly ground silica and the related lipid peroxidation of the memberanes may be the starting point of the silicotic processes.INTRODUCTIONDespite considerable-effort over the years, the mechanism by which the quartz particles exert their toxic action on cells and the process(es) by which these actions progress to fibrosis are still not fully understood (1,2). It is generally thought, nevertheless, that the interaction of the quartz particles with the cell membranes is the starting point of the silicotic process (3). We felt that the mechanism of the membrane damage by quartz might involve oxygenated free radicals because (a) a suspension of quartz particles in contact with alveolar macrophages has been reported.(4,5) to initiate an enhancement of lipid peroxidation, defined broadly as the ;oxidative deterioration of polyunsaturated components of lipids, and (b) hydroxyl (·OH) radicals are known to be capable of peroxidation by abstracting hydrogen atoms from cell-membrane lipids (6) and initiating lipid peroxidation in lysosomal membranes (7). Moreover it is known that exposure of cell membranes, fatty acids and unsaturated food oils to ionizing radiation, which generates ·OH. radicals, causes rapid peroxidation (6). Earlier studies o~ the aqueous chemistry of quartz suspensions have reported detection of HzOz (8), implicating the formation of ·OH radicals as transient species, but, we are not aware of any report of the detection of ·OH radicals in quartz suspensions and this provided the motivation for the present undertaking. Since it is known that, because of their high reactivity (hence short life time) in aqueous media, the ·OH radicals cannot be detected via electron spin resonance (ESR) directly (9,10), we have used ESR combined with the spin-trap methodology (9) for studying the •OH formation."

Jan 1, 1988