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By Wing G. Agnew, Paul L. Russell

"INTRODUCTION During the past few years, the development of millisecond-delay electric blasting caps has made possible a more flexible control over timing the firing of individual charges in blasting, The use of these caps has proved especially productive in quarry blasting and in numerous construction operations, but their use in underground mining is developing more slowly, although in some cases, as the solution to a difficult breaking problem, they have been well-received. When used in metal-mine drifts, the general objection is that the broken rock is thrown too far. In nearly all cases, however, use of millisecond-delay caps results in better fragmentation of the rock and a lower powder consumption per ton of rock broken.Prom 1949 to 1952, several series of experiments were conducted at the Mount Weather, Va., Experimental mine in conjunction with driving a 6- by 10-toot ventilation raise. 3/4/ The raise-round experiments in this 238-foot shaft, using millisecond-delay electric blasting caps in various drill-round patterns, are the subject of this report.SUMMARY AND CONCLUSIONSAll rounds discussed in this report were drilled in the hard rock (epidosite and greenstone) of the ventilation raise at Mount Weather Experimental mine (figs. 1 and 2). The drill-round patterns varied from 28- to 32 holes and from a V-cut design to one having no cut boles at all. With the exception of the first two rounds, all blasting was done with millisecond-delay electric blasting caps. In all rounds 60-percent ammonia gelatin dynamite was used and holes were stemmed with two cartridges of sand stemming."

Apr 1, 1953

By William S. Roberts

As part of the Bureau of Mines critical and strategic minerals program in Alaska, 34 high-purity chromian spinel samples were analyzed for trace and major element geochemistry and mineralogy. The samples were analyzed by X-ray diffraction, X-ray fluorescence, and chemical techniques. Systematic differences in chemistry are evident when samples collected from the Chugach Mountains and their related extension are compared with chromian spinel samples collected from interior Alaska. Compared with the Chugach samples, the interior Alaska samples have higher average amounts of A1203, Fe203, Ti02, and NiO, have lower average amounts of FeO and Cr203, and exhibit greater dispersion in values. Considerable mineralogical variability of chromian spinel exists between and within individual Alaskan chromite-bearing ultramafic complexes. Of 34 samples analyzed, 25 samples are magnesiochromite, 5 are chromite, 3 are spinel, and 1 is hercynite. As a group the interior Alaska samples have a smaller average unit cell dimension than the Chugach group of samples. The chemical and mineralogical differences between the two groups of samples can be attributed to different genetic histories and may have implications for locating chromian spinel deposits amenable to standard beneficiating techniques.

Jan 1, 1985

By J. M. Stuve

Thermodynamic properties were determined by the Bureau of Mines for the intermetallic compound, TiA13. Heat capacities were obtained from 5 to 303 K by adiabatic calorimetry. The derived value of S2 1s is 22.08±0.07 cal/deg¬mole. Enthalpies relative to 298 K were obtained from 298 to 1,413 K by copper-block drop calorimetry. No anomalous thermal behavior was noted in the temperature ranges investigated. Low- and high-temperature data were combined with a known enthalpy of formation at 298 K to give values of enthalpy of formation and Gibbs energy formation, 0 to 1,400 K.

Jan 1, 1974

By W. J. Kroll

This report is concerned with the many sidelines that were investigated incidental to developing a process to produce ductile Zirconium by members of the staff of the Bureau of Mines laboratory, Albany, Oreg. The results of the main investigation, concerning the production of malleable zirconium by reduction of chloride with fused magnesium under helium, have been described in previous publications. These should be taken as a background to facilitate understanding of this work. Literature on the metallurgy of zirconium has been summarized in a separate publication (2), and references are given in this report only when new publications have to be considered or old ones stressed. Most of the observations described in this report can be applied to the problems involved in making titanium with virtually no change. In general, titanium is easier to reduce than zirconium, since its affinities are lower. Also, its chloride is easier to handle and keep clean because it is a liquid at room temperature.

Jan 1, 1952

By Lee Blackman

The Malheur-Jordan Resource Areas (MJRA?s) is a tract of approximately 6.5 million acres of federal and non-federal land in the southeast corner of Oregon. This study evaluated the Resource Areas' economically recoverable mineral potential based on geological estimates provided in the USGS report (Smith, 1994). The mineral terranes are believed by geologists to contain undiscovered resources. The geological data is probabilistic; with estimates of the possible number of deposits and their grades and tonnages. Possible future development scenarios range from no development to numerous mines. Based on the analysis performed on these terranes, the most likely (in a statistical sense) future scenario for the resource areas would include the potential for two medium sized, predominately gold, mines. These would supply direct and indirect employment of up to about a thousand workers.

Jan 1, 1995

By N. S. Dalal, X. Shi, V. Vallyathan

"Correlated spectroscopic and cytotoxicity measurements were made on newly crushed silica to find whether the fracture-induced, silicon related (Si-0· or Si· type) free radicals play a direct role in the mechanism of hemolysis by silica particles. The free radical content of the silica particles was controlled through the radical decay, thermal annealing, and boiling processes, and was followed with electron spin resonance spectroscopy. Portions of the same sample were evaluated for their hemolytic potential, employing sheep erthyrocyte and optical absorption techniques. The results indicate little, if any, correlation between the amount of the silicon-based radicals and the hemolytic potential of the fresh dusts, but these or related radical sites might be contributors to silica cytoxicity and fibrogenicity via peroxidative pathways .INTRODUCTIONIn an earlier convnunication (1.) from our laboratory it was reported that mechanical crushing of coal and quartz under normal air atmosphere generates free rad;cals on the particle surfaces, and that these radicals decay with time, hence pointing to a higher toxicity of fresh dusts in relationship to pneumoconiosis and silicosis. More recently Fubin; et al.(2) have also reported the detection by electron spin resonance (ESR) of the formation of SiO· and Si·-type of radicals from quartz particles crushed under atmospheric conditions. In agreement with earlier ESR studies on single crystals of quartz crushed under high vacuum (10-10 torr) (3) and subsequent exposure to air (3), and to other gases (4), these radicals were identified (2) as being formed by the hemolytic cleavage of the Si-0-Si bonds and the reactions of the Si· and SiO· ,radical with atmosphere. Fubin; et al. (2) also suggested that these radicals might be involved in the mechanism of the fibrotic action by silica, either by transforming the particle surface into a selective oxidating agent or as an initiator of a sequence of reactions leading to fibrosis. Earlier Gabor and Anea (5) had reported that lipid peroxidation caused by free radicals on the silica surface might be involved in the red blood cell membrane damage. Thus far, however, no parallel cytotoxicity, fibrogenicity, and free radical studies on a given Quartz dust sample have been reported, except for some earlier work from our laboratory (1,6,7). We now present more recent results obtained from parallel cytotoxicity, fibrogenicity, and free radical measurements on a freshly made quartz dust. The dust’s free radical content was measured using ESR spectroscopy while its cytotoxicity poteni1al was estimated via hemolysis. Hemolysis was employed as the tox1c1ty test because it 1s a widely used method for estimating the potential of a dust for disrupting the cell membrane (8). The f1brotic potential was followed.by measuring the dust-induced lipid perox1dat1on. us1ng linole1c ac1d as a model lipid. As discussed below, the results obtained suggest new clues.to the mechanism of the Quartz-related cytotoxicity and fibrogenicity."

Jan 1, 1988

By R. J. Campbell

[The steady increase of aluminum production means a corresponding increase of carbon consumption in the alumina-reduction cells. Improved petroleum techniques constantly reduce the amount of byproduct petroleum-coke production. These, trends threaten the alumina-reduction works with possible shortages of carbon, which must be supplied from some other source. In anticipation of this shortages, an investigation into the possibility of using coal as an alternative source of carbon was begun at the Northwest Experiment Station of the Federal Bureau of Mines. The investigation lit has developed bench-scale methods that produce carbon of higher purity than is required by specifications for anode carbon. Additional work will b required to bring these processes to pilot-plant seals and to prove the suitability of the carbons, produced or aluminum-anode consumption.]

Jan 1, 1956

By R. J. Leary

A small electronic digital computer employing punched cards has been used to facilitate the solution of a variety of problems in Bureau of Mines pyrometallurgical research. In this work the computer has been found to be economical for solving both simple problems that occur repeatedly and those involving complex or iterative calculations. Each of these classes of problems and their respective solutions are described. These small computers can be used effectively by researchers when they work in consultation with a computer specialist. Close team work produces the required solutions in less time, and, oftentimes, in a more useful form. Participation in programming by researchers develops in them a skill for evaluating the suitability of problems for electronic computing.

Jan 1, 1960

By Catherine C. Kilgore

The Bureau of Mines investigated the availability of manganese from known domestic occurrences. Eight of these deposits were found to have demonstrated resources totaling 420 million metric tons with an average grade of 10 percent contained manganese. They were found to be submarginally subeconomic. Economic evaluations of the eight deposits resulted in incentive prices ranging from $8 to almost $35 per long ton unit (22.4 pounds) of contained manganese. Comparing these prices with the current market value of $1.70 per long ton unit of manganese clearly illustrates the submarginal nature of the domestic ores analyzed. These domestic resources would probably not be developed except in the case of an extreme national emergency. Production from the eight deposits would take 3 to 6 years to develop, and the final product would be manganese ore concentrate, which could be used in the production of ferromanganese. If preproduction development began in 1981, annual production would peak in 1987 with 900,000 metric tons of recoverable manganese. Thereafter, production would see a steady decline unless additional resources were located or technologic improvements were made to allow processing of lower grade material, or unless mining and processing of ocean manganese nodules began to take place.

Jan 1, 1982

In 2005, a total of 4,490 stone mining operations reported employment to the Mine Safety and Health Administration (MSHA). Stone mines comprised 30.6% of all mining operations. ? Mines producing the primary commodity of limestone (crushed and broken) comprised the largest number of operations (n=2,039; 45.4%). ? Stone mining operations were located in all states and territories except Delaware and North Dakota. ? Of all states, Pennsylvania had the most stone mines (n=379; 8.4%).

Jan 1, 2008

By F. R. Cattoir

This Bureau of Mines study investigated molten salt electrorefining for beneficiating low-grade, high-carbon ferrochromium products which can be readily produced from domestic chromite concentrates. A second objective was to refine commercial ferrochromium into low-iron chromium products. Electrorefining of both types of ferrochromium in molten CaC12-NaCl-CrC12, CaCl2-MgC12-CrCl2, or KC1-LiCl-CrCl2 electrolytes produced chromium-iron products with virtual elimination of other impurity elements and some lowering of the iron content, Over 90 percent of the chromium present in the feed materials was recovered. The electrodeposited products were upgraded further by magnetic separation techniques into chromium containing less than 5 percent iron. The technical feasibility of preparing a premium chromium product from a low-grade, high-carbon ferrochromium made from domestic chromite was demonstrated. Chromium virtually free of carbon, oxygen, and silicon from high-carbon ferrochromiums was produced. In addition, the amenability of three commercial grades of ferrochromium to electrorefining and magnetic separation for preparing chromium metal containing less than 5 percent iron was determined.

Jan 1, 1969

By O. C. Blade

A summary of the characteristics of motor gasoline for the winter 1951-52 is presented in table I, and for comparison, a similar summary for the winter 1950-51 is shown in table 2. Trends of some of the more important characteristics over a period of years are shown in figures 1 and 2. The results of this survey show that octane numbers have risen slightly since the summer of 1951 but are below the record levels of the winter of 1950-51. The fractions of a unit change since the summer preceding have resulted in the research and motor-method octane values being virtually the same as the figures for the survey of summer 1950. In volatility characteristics the winter gasolines have changed very little. Average Reid vapor pressures are 10.5 pounds for both grades of fuel compared to 10.4 and 10.5 pounds for premium and regular-price gasolines, respectively, of the winter of 1950-51.

Jan 1, 1952

By F. X. Tartaron

Behavior of hard-burned quicklime was compared with that of soft-burned quicklime in an oxygen converter utilizing oxygen blowing in a rotating cylindrical vessel, set at a 30° to 60° angle to the horizontal and operated at a predetermined speed of rotation. Four pairs of tests were made) each comparing hard lime with soft lime. Three of the pairs differed from one another in the quantity of lime employed) and the fourth differed in blowing time, All four pairs showed an increase in yield when soft lime was used. Three of the pairs revealed that the ratio of the oxygen consumed with soft lime to the oxygen consumed with hard lime was the same as the ratio of metal yield with soft lime to the metal yield with hard lime. The fourth pair contained an error and could not be included. Finally, a close inverse relation was found between the combined iron in the slag and the combined lime in the slag, which can be expressed by the equation pct Fe = 52.67 -0,906 (pct CaO).

Jan 1, 1967

By S. C. Rhoads

The Bureau of Mines is investigating low-chromium alloy substitutes for type 304 stainless steel (type 304 SS). The purpose of the research is to reduce the chromium content in austenitic stainless steels used for corrosion-resistant applications. Nine Fe-9Cr-12Ni alloys containing additions of 0 to 5 pct Mo, 0 to 2 pct V, and 0 to 2 pct Cu were selected for evaluation. All of the experimental alloys containing 5 pct Mo and an alloy containing 2Mo-2V-2Cu possessed structure and tensile strengths similar to those of type 304 SSe Alloys containing SMo-2V and SMo-2V-2Cu had ac-ceptable welding properties as measured by the Varestraint test. Alloys containing at least 2 pct Mo had cQrrosion resistance comparable to that of type 304 SS in solutions of nitric acid, phosphoric acid, acetic acid, and citric acid. In chlorides, all the experimental alloys were susceptible to localized corrosion and stress corrosion cracking similar to that of type 304 SSe The corrosion properties were established by weight-loss tests, electrochemical polarization tests, and stress-corrosion cracking tests. An Fe-9Cr-12Ni-SMo-2V alloy and an Fe-9Cr-12Ni-SMo-2V-2Cu alloy had a combination of welding properties, tensile properties, and corrosion resistances that were most comparable to those of 304 SS.

Jan 1, 1984

By William J. Campbell

Evaluation by the Bureau of Mines of published expansion values for magnesium oxide shows significant variation in values, which may be attributed to sample variables, experimental errors, or systematic differences between measuring techniques. To eliminate the sample variable in measuring expansion, thermal expansion characteristics of a high-purity polycrystalline magnesium oxide were determined by 21 cooperating laboratories using one or more of the following techniques; X-ray camera, X-ray diffractometer, dilatometer, interferometer, and telemicroscope. All expansion values were corrected by the author to a single reference temperature of 25° C. Linear expansion was expressed as a power series in the form of the following equation. Expansion (percent) = [[ A + B (?t) + C (?t)2] ?t 104] The constants, A, B, and C, were determined by least square techniques for X-ray camera, X-ray diffractometer, and dilatometer data separately, and for combined data of all five techniques. Expansion values are tabulated from 26° C. to 1,400° C. in 2° C. intervals using constants derived from X-ray camera data. Below approximately 500° C., expansion values obtained by dilatometric and interferometric methods are significantly lower than those by X-ray methods; above 500° C., this bias decreases rapidly. Comparison of results within methods showed the least variance for X-ray camera results; dilatometer and X-ray diffractometer results have about the same variance. The average deviations, in percent, between observed and calculated expansion values among methods were approximately 10 percent from 100°C. to 300°C., 5 percent from 300°C. to 500°C., and 2 percent from 500°C. to 1,400°C. Maximum deviations were approximately twice as large in most instances.

Jan 1, 1962

By A. W. Decora

Gas-liquid chromatography has been applied to separating basic nitrogen compounds, such as pyridines and amines. Close-boiling compounds have been separated by exploiting structural and polarity differences, using selective liquid substrates dispersed on specially prepared solid supports. Development of these special supports was necessary in order to obtain symmetric peaks for basic nitrogen compounds; solution of this problem was important in applying gas-liquid chromatography to the analysis of basic nitrogen compounds found in shale oil. Attempts to analyze shale-oil tar bases by conventional gas-liquid chromatographic techniques, using Chromosorb4/ or Celite 545 as the support for a nonpolar liquid substrate, resulted in asymmetric peaks. These asymmetries were caused by adsorption of sample vapors on the solid support. Symmetric peaks were obtained when strongly polar liquid substrates were used on either Chromosorb or Celite. However, a solid support giving symmetric peaks only with strong polar substrates restricts the choice of substrate, and frequently, desired separations cannot be achieved.

Jan 1, 1961

By V. E. Edlund

This report presents the results obtained in a study of the technical feasibility of recovering a usable pig iron by pyrometallurgical treatment of typical copper reverberatory slags . The iron in the slag was readily reduced with carbon , but the copper and sulfur content of the metal was best controlled by a three - stage procedure comprising ( 1 ) melting the slag with pyrite to remove copper as a low- grade matte , ( 2 ) smelting the partly decopperized slag with fluxes and carbon to reduce the iron , and ( 3 ) refining the impure iron alloy from step 2 with a flush slag to remove sulfur and residual copper . Laboratory - scale tests demonstrated that washing with 8 wt pct of pyrite lowered the copper content of a typical reverberatory slag from 0.58 to 0.12 Subsequent smelting of a mixture composed of 70 pct decopperized slag , 25 pct lime , and 5 pct coke reduced 84 pct of the iron to metal containing 2.27 pct sulfur . This metal then was successfully desulfurized by treatment with a basic flush slag to produce a finished metal that contained , in percent , 93.5 Fe , 0.02 S , 0.26 Cu , and 4.9 C. Overall recovery of iron under the conditions of trial was about 80 pct . This could be increased if higher tolerances for copper could be accepted . Commercial processing would be accomplished in three furnaces with molten materials passing from one to another . Currently produced smelter slag could be treated fairly inexpensively , because the molten product would require only a little additional heat to produce an iron byproduct that undoubtedly would be attractive to local foundries .

Jan 1, 1964

By J. A. Organiscak

Quartz dust is one of the most significant ongoing health concerns in coal mining today. Since the early 1980's, the U.S. Bureau of Mines has conducted numerous studies in underground and surface coal mines to identify the sources of quartz dust and its fundamental characteristics. This report presents data and conclusions obtained from these studies. The two most significant quartz dust sources were found to be the continuous miner excavating rock and the highwall drill operating in a rock overburden. The percentage of quartz was found to be higher in the smaller size fractions of dust when significant amounts of rock were mined by the continuous miner. Another factor theorized to affect quartz dust generation and size characteristics is the morphology of the quartz-bearing rock. Several laboratory studies were conducted to investigate capture efficiency of water spray technology and flooded-bed scrubbers with respect to the particle size of the dust. Water sprays and flooded-bed scrubbers were both found to be less efficient on smaller dust particles, and the scrubber was particularly less efficient on quartz dust. These results indicate that quartz control technology should be directed at controlling smaller sized dust particles.

Jan 1, 1990

By Raja V. Rarnani, Robert L. Frantz

"The more than 75 research projects funded throughout the first 10 years of the Dust Center's operation have resulted in numerous cumulative findings fulfilling the goals of the Center. These project descriptions present the methodologies and project-to-project relationships leading to their various accomplishments and demonstrate the mesh between project objectives and Center goals.To develop equipment for collecting respirable dust samples.To develop experimental methods for particle-by-particle characterization of morphology, size, and chemistry.To develop experimental methods for overall respirable dust sample characterization of size distribution, chemistry, and crystallography.The project directly addresses the Center's goals to enhance the understanding of the scientific and engineering characteristics of fine and respirable mineral particles found in mining and milling atmospheres and to establish the relationship between natural and cultural factors (mine geology, mineralogy, mining and milling methods, equipment, and control measures) in the generation of fine particles. The project also aims to contribute to the development of control mechanisms for reducing ambient respirable dust concentrations and worker exposures.The work on this project is related to similar work on Coal Mine Dust Characterization (Project No. 2701/MN1) and Characterization of Dust Particles (Project No. 4203/PS3).Airborne dust sampling was performed at the following locations: 1) a sand and gravel quarry in Southern New Hampshire, 2) a welding facility, 3) a ceramic powder facility, 4) a metal powder facility, and 5) the air in Cambridge, Massachusetts. A portable sampling box incorporating two Sierra personal cascade impactors was designed and produced. At a 2-LPM flow rate, the effective cut-off diameters of the Sierra impactors were 10.0, 6.0, 3.5, 2.0, 0.9, and 0.5 mm, respectively, for each stage, and the air passed through a PVC filter after the last stage. In addition, the sampling box contained a total respirable dust filter. The substrates were weighed carefully before and after collection, and the weight increases were recorded. All films, foils, and filters were put in the balance chamber for more than 8 hours to stabilize the temperature and humidity before weighing. A Cash 21 microbalance (±0.001 mg) was used to weigh the Mylar films, SS films, and filters."

Jan 1, 1995

By E. P. Youngman

Before the World War the use of zirconium and its compounds was largely experimental and confined almost wholly to Germany and Austria . Occasionally small lots of zirconium ore had been produced in the United States ( 1,000 pounds in 1869 , 26 tons in 1883 , and 3,000 pounds in 1903 ) and used (with monazite ) in the manufacture of various lighting devices , especially incandescent gas mantles ; but it was not until 1906 that the discovery of the natural zirconium oxide in large quantities near Sao Paulo , Brazil , first gave promise that a zirconium industry eventually might be developed . Edward Rietz , who worked the Brazilian deposits , interested German chemists in extending the use of zirconium , and by 1911 trade journals were listing German firms as manufacturers of compounds or products derived therefrom . For a time zirconia was one of the various oxides used in the Nernst lamp . It was used also for crucibles and hearths as refractory material ; in the manufacture of chemical utensils ; in enamels ; in the place of bismuth subnitrate for defining Röntgenray pictures of the stomach ; as a pigment ; in medicine ; and in a number of other ways . The Germans were credited also with producing a remarkable zirconium steel , which , it was claimed , was much superior to other alloy steels . During the World War the United States Government investigated the possibilities of zirconium , as well as those of other steel -hardening elements , and a large automobile manufacturer actually purchased a substantial quantity of ore with the purpose of employing zirconium in automobile steels . Immediately after the armistice the Government ceased its investigations ; but despite the difficulties experienced by various investigators in reaching concordant results , interest in the use of zirconium as a steel -hardening agent , as well as in other uses of the element and its compounds , continued . In 1918 the Foote Mineral Co. , which had been interested in zirconium for several years , was exploiting the deposit in Brazil formerly worked by the Germans and was supplying zirconia in the form of ore , brick , and cement for refractory and other purposes . About the same time the Electro Metallurgical Co. , which before the entrance of the United States into the war was experimenting with zirconium alloys , supplied in tonnage quantities the demand for these alloys . In 1919 it was reported that American manufacturers , after several years of research, were producing in commercial quantities pure zirconium oxide , which was finding a place in the manufacture of small refractory articles , scorifying dishes , crucibles , tubes , and one- piece furnace linings . In 1920 the lowering of the price of zirconium metal powder ( because of improved metallurgical methods ) promised the production of the metal on a semicommercial scale . In 1924 the Titanium Alloy Manufacturing Co. introduced a new opacifying agent , " Opax , " made from zircon . A year or two later some of the large pottery manufacturers became interested in the use of zirconium oxide as an opacifying agent , the increased production of titanium pigments having resulted in the production of zirconium as a by-product at a price that could compete with tin oxide . In 1928 it was reported that the industrial use of zirconium oxide was increasing steadily in the manufacture of brick , crucibles , and other refractory products , such as high- temperature cements . However , the reluctance of producers to install additional and more suitable

Jun 1, 1931