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By J. W. Walkiewicz

The Bureau of Mines investigated alloys containing mischmetal (MM), cobalt, copper, magnesium, and iron for use in permanent magnets in place of the scarce samarium-cobalt alloys. The magnetic properties of MM-Co, MM-Co-Cu, MM-Co-Cu-Mg, and MM-Co-Cu-Fe-Mg alloys were evaluated. Magnets were fabricated by powder metallurgy consisting of arc-melting the metals, crushing and grinding the resultant alloys, alining and compacting the powder, and sintering the compacts. Magnetic values of MHc = 4.7 kOe, BHc = 4.07 kOe, Br = 6.81 kG, and (BH)max = 10.0 MGOe were obtained with a MM-Co alloy containing 36±0.5 wt-pct MM. By substituting copper and magnesium for part of the cobalt, the values for MHc and BHc were increased to 29.0 kOe and 5.89 kOe, respectively. This intrinsic coercivity value exceeded that of Sm-Co alloy obtained in our laboratory. The addition of iron to MM-Co-Cu-Mg alloys resulted in an increase of Br to 6.90 kG and (BH)max to 10.3 MGOe. Copper and magnesium contents of these alloys were optimized to obtain maximum values of MHc.

Jan 1, 1981

By Benjamin W. Haynes

Materials from phosphate rock mining and processing were analyzed for fluorine and uranium content as part of the Bureau of Mines program to more effectively recover resources from mining and mineral processing reject materials. The analysis of both feed and waste materials generated in the beneficiation and acidulation of phosphate rock was performed to obtain information on the disposition and concentration of these elements in phosphate rock processing streams. Fluorine was determined by a distillation-titration method and by ion chromatography. Uranium was determined by the dibenzoylmethane (DBM) method, the reliability being confirmed by roundrobin analysis of samples within Bureau of Mines research centers. National Bureau of Standards (NBS) Standard Reference Material (SRM) 120b-Phosphate Rock was also analyzed for fluorine and uranium to verify procedures and results. Fluorine values ranged from 0.3 wt-pct in gypsum filter cake to 3.7 wt-pct in phosphate rock concentrate. Uranium ranged from less than 5 µg/g in gypsum filter cake to 200 µg/g in a dried clay slime.

Jan 1, 1981

Measure dangerously high concentrations (20 to 500 g/m3) of flammable, airborne dust. Approach Development of high concentration dust monitor (HCDM) which will measure mass concentrations of air borne dust by the principle of beta-ray attenuation. How It Works The HCDM is a battery powered, portable instrument that weighs 10.5 kg. It is capable of making continual (10 sec. time resolution) measurements of high concentrations of airborne dust and can record up to 8 hours of data in an internal memory. The data can be read out later on an analog or digital recorder. An internal pump pulls airborne dust into the sampling section, which contains a low-energy beta-ray source and a Geiger counter detector. No beta radiation escapes from the instrument, and no license is required for the operator. The mass concentration measurement is made while the dust is still airborne. Beta-ray attentuation is independent of particle size and composition of the dust, so the HCDM can he used with many types of dusts which may be airborne in flammable concentrations. A knowledge of the composition and minimum explosive concentration of the dust is necessary to understand the significance of the data from the HCDM. The HCDM was designed to measure air-

Jan 1, 1982

The Federal Mine Safety and Health Act of 1977* defines respirable dust as dust measured with a device approved by the Secretary of Labor and the Secretary of Health and Human Services [30 USC 842(e)]. The approved sampler for respirable coal mine dust is the coal mine dust personal sampler unit (CPSU) [30 CFR 74; Jacobson 1971; Jacobson and Lamonica 1969]. The CPSU is generally called the 10-mm nylon cyclone, although the 10-mm nylon cyclone is actually just one component of the CPSU. The CPSU may either be mounted on a worker (with the sampling head positioned in the breathing zone for personal exposure monitoring) or in a fixed location for area sampling [Tomb 1990]. The CPSU consists of a pump unit, a sampling head assembly, and a battery charger if rechargeable batteries are used in the pump unit [30 CFR 74.2]. The sampling head assembly contains two stages. The first stage is a 10-mm nylon cyclone, which has collection characteristics similar to an elutriator. The amount of dust penetration depends on the flow rate [Jacobson and Lamonica 1969]. The second stage is a membrane filter (vinyl, pore size 5 pm) that collects the dust passing through the cyclone. The dust collected on the membrane filter is weighed to a precision (standard deviation) of 81 pg [Parobeck et al. 1981], and the respirable dust concentration in the mine atmosphere is then determined from the mass of dust collected and the volume of air sampled [Tomb 1990].

Jan 1, 1997

By F. C. Gregory

"Introduction.The third annual mine-rescue maneuvers of the Globe-Miami District First Aid and Mine Rescue Association were held at Globe, Ariz., on November 5 and 6, 1923. The first demonstration was held in October 1922, and the results** from that experiment, both in the practical training and the interest aroused in the apparatus men, were so much more satisfactory than those from the ordinary smoke-chamber training, that Orr Woodburn, director of the Association, decided to hold similar maneuvers at frequent intervals. The second test was held on March 21-22, 1923, in connection with the meeting of the Southwest Mining Section of the National Safety Council at Globe.Place and Organization.The recent maneuvers were held in the same mine and conducted in the same general manner as the first, and the points of interest not brought out previously are described below. By studying the accompanying map the movement of the teams can be better understood.Thirty-three apparatus men were out on the first day and thirty-two on the second day, a total of forty-three men being trained.Mr. Woodburn was aided in directing the work by his two assistants from the mine-rescue station, two local safety engineers, and an engineer from the Bureau of Mines. Local mine superintendents and the State deputy mine inspector were interested spectators."

Jan 1, 1924

By Árpád B. Palotás, Adel F. Sarofim, John B. Vander Sande, Paolo Ciambelli, Lenore Rainey

"The evolution during oxidation of the internal structure of soot and carbon black particles was studied using high-resolution transmission electron microscopy (HRTEM) and an image analysis system. Increasing ordering to the carbon structure with increasing oxidation is observed. Measures of the increased order are increases in the fractional coverage of a cross section of the particles with a layered structure, a decrease in the mean interlayer spacing, and a decrease in the spread of the interlayer spacing. The changing structure of the carbon black impacts its properties, such as the rate of oxidation.There is considerable interest in the study of the structural changes of carbonaceous materials as a function of oxidation. Davis et al.1 measured the variation of carbon dioxide surface area of various coals as a function of residence time in a flow reactor. HRTEM measurements revealed that crystallite dimensions and interlayer spacings are altered by combustion. Ishiguro et al.2 showed that oxidation alters the structure of diesel soot. The aim of our current research is to develop a better understanding of the microstructural reordering of carbon blacks with implications to their properties. The carbon blacks used in this research have already been studied and their reactivities as a function of oxidation measured.3The methodology used in this work has already been described in detail elsewhere.4 This paper presents an application to quantify the structural changes of carbon black particles as a function of oxidation and graphitization. The technique used is based on the use of HRTEM (high-resolution transmission electron microscopy) and computational image analysis.It is well-known that carbonaceous materials like graphite, soots, coals, chars, etc., possess characteristic structural appearances which can vary from mostly random or amorphous to a perfectly ordered graphitic crystalline structure. The carbon structure has been variously described as turbostratic5 or as crumpled sheets6 to indicate that parallel layering, reminiscent of graphite, is observed over dimensions of nanometers but that these planes or crystallites show disorder over larger scales. The degree of order of such structures is strongly dependent on the thermal treatment of the material as well as the composition of the source of the carbonaceous material. The value of electron micros¬copy in studying the morphology of such materials has been well established,2,7,8 although only a few attempts toward quantification have been made.The sample observed was carbon black CB330 from De¬gussa. One set of carbon black samples were oxidized in a thermo-gravimetric analyzer (TGA) in air at 575 0C, so that the conversion varied from 0 to 96%. Another set of carbon black samples were graphitized (Graphpac-GB by ALLTECH) and then oxidized in the TGA at 680 °C until 92% burnout was reached. The latter samples are called GB 0% and GB 92%, respectively.For the HRTEM observation a small portion of each sample was ultrasonically dispersed in ethanol. The suspension was deposited dropwise on a copper TEM grid coated with a lacey carbon film. The examination of the samples was carried out on areas that extend over the holes in the supporting film in order to avoid interference from the amorphous carbon background film An oriented gold crystal was used as a calibration standard and subjected to the same techniques as the carbon black samples."

Jan 1, 1998

By William H. Pomroy

Spontaneous combustion fires involving high-sulfide-content ores are a relatively infrequent yet serious safety hazard in mining. They are also the cause of lengthy mine shutdowns because they typically occur in areas of a mine where abundant fuel material is present but which are inaccessible for fire fighting. This Bureau of Mines report describes research to design, fabricate, and test in the laboratory and field a system that warns of spontaneous combustion fires in metal mines. Overall performance of the detection system was found to be satisfactory, in that the system was capable of reliably detecting low levels of combustion products believed to indicate the preflaming stage of spontaneous combustion in metal mines. Installation of similar systems in mines with a high risk of spontaneous combustion is recommended. Principal operating problems and recommended corrective actions are also discussed.

Jan 1, 1987

By S. R. Wilson

[The Anniversary-Bucky pegmatite is one of the largest, dikes in the Quartz Creek district, 21 miles east of Gunnison, Colo. The major dike consists of quartz-albite pear pagmatite and graphic granite with many quartz masses as individual cores occurring within the dike. A mining operation on one of the largest core areas has exposed several mineralogic cones directly associate with the core. These zones, including the large- units of the dike, are quartz pegmatitc, quartz-perthite pegmatite, perthite pegmatite, muscovite-feldspar -quartz pegmatite, quartz-albite pegmatite, and perthite-quartz (graphic granite) pegmatite. Muscovite and beryl are found in the muscovite-feldspar-quartz zone and are the only two products that have been marketed. Other potential products are perthite, graphic granite, and possibly small quantities of columbite-tantalite, monazite, and related radioactive minerals. The Bureau of Mines drilled two diamond-drill holes during April 1950 to investigate the largest and cost promising core area. This, report describes the results of this drilling.]

Jan 1, 1953

By Yael Miron

ANFO blasting agents may undergo an exothermic reaction when they contact warm ore bodies that contain pyrite and its weathering products. The reaction is very fast at temperatures above 80° C. Urea, when present in sufficient amounts, inhibits this reaction at temperatures below 180° C. But urea-ammonium nitrate mixtures are very hygroscopic and, in certain climates, may be difficult to handle in the field. Reaction-inhibiting characteristics of three compounds were reported by the Bureau of Mines in 1979. Recently, the Bureau investigated the reaction-inhibiting qualities of five additional compounds. Mixtures of ANFO, pyrite, weathering product, and prospective inhibitors were slowly heated, under conditions simulating a hot borehole, to determine prospective inhibitor capability at temperatures up to ~175° C. Small-scale thermal tests of the same mixtures were used for verification and clarification of results. Two organic compounds, phthalimide and xanthine, similar in structure to urea, failed to inhibit the reaction. Zinc oxide and calcium carbonate were found inferior to urea, though zinc oxide raised the onset of reaction from 80° C to about 140° C. Only magnesium oxide was found to be similar to urea in its inhibitory ability at temperatures below 175° C. Based on results from analysis of quenched residues, the use of more than 5 wt-pct magnesium oxide is recommended.

Jan 1, 1982

By K. P. V. Lei

The Bureau of Mines as part of its research effort to minimize the generation of hydrometallurgical waste, investigated a sodium sulfide leaching-electrolysis procedure for treating hydrometallurgical residues for elemental sulfur and base-metals recovery. Research was conducted on a leaching residue from a lead concentrate. The following procedure was developed. 1. The elemental sulfur was dissolved as polysulfide with an Na2S solution. 2. The resultant metal sulfide bearing residue was oxidatively acid leached in a cationic membrane electrolysis cell; the metals were solu¬bilized at the anode, and a base was generated at the cathode. 3. The elemental sulfur was recovered from the polysulfide solution by neutralizing with the acid in the anolyte. Byproducts of the neutralization were H2S and a sodium salt solution. 4. Sodium sulfide was regenerated by reacting the H2S byproduct with the base in the catholyte. 5. Lead as PbCL2 was recovered from the anode residue by brine leaching, and the other metals were recovered from the sodium salt solution as metal sulfides. 6. The barren filtrate from the metal sulfide precipitation constituted the recycled electrolyte. Ninety-eight percent of the elemental sulfur, 98 pct of the lead, and up to 80 pct of other accessory metals were recovered from a residue obtained from the FeCl3-NaCl leaching of a lead concentrate.

Jan 1, 1982

By K. K. Kershner

Important contributions can be made to conservation of natural resources by recovering mineral values from primary and secondary metallurgical slimes and flue dusts. This applies particularly to ultrafine mineral particles that escape recovery by conventional mineral dressing. In the interest of economy and conservation the Bureau of Mines is investigating fundamental properties of ultrafine mineral values in slimes as a means of developing new or improved methods of mineral recovery. The work described in this progress report was carried on in the Bureau's laboratories at Rolla, Mo., from 1951 to 1953. The mineral material used as a subject for study was tin-ore slimes. DESCRIPTION OF TIN SLIMES The tin slimes consist principally of quartz, with appreciable quantities of tourmaline and sericite mica and small amounts of cassiterite, pyrite, hematite, and arsenopyrite. The tin content is approximately 0.5 percent.

Jan 1, 1954

By R. V. Ramani, S. Shankar

"A convective dispersion model has been utilized to calculate the real-time airborne dust concentration in mine airways using re-entrainment as the only source term for airborne dust. It incorporates two important sources of re-entrainment in mines -- air velocity and movement of objects. The model has a sink term accounting for the deposition of particles along the airway. The model is solved using a finite difference scheme which is coded for computer. The computer model outputs airborne respirable and total dust concentrations along the airway as a function of time. The real-time and average gravimetric concentrations from several in-mine experiments were compared with the results from the simulation of the experimental conditions. This model can be used for estimating airborne dust entrainment due to air velocity, equipment movement, and persons walking. INTRODUCTIONEdwards and Ford (1988) developed a model for coal dust explosion suppression and utilized a predetermined value of threshold velocity for flowing air to pick up dust from floor. Depending on the strength of the removal forces, re-entrainment can increase the airborne dust concentration in mine airways. The most prevalent forces causing re-entrainment in mine airways are the drag and lift forces due to flowing air, and removal forces due to the movement of persons and vehicles. Shankar and Ramani (1991) have investigated the unique characteristics of the re-entrainment phenomenon in mine airways. Experiments on re-entrainment of coal dust particles were conducted in mine airways, and in a wind tunnel (Shankar and Ramani, 1994a, and 1994b). The results from the two experimental studies were found to compare well (Shankar and Ramani, 1995). There is no reported model to determine the airborne dust concentrations due to airflow or persons walking under conditions existing in mines. The present study is a part of a continuing research project in the Generic Mineral Technology Center for Respirable Dust on the spatial and temporal behavior of airborne dust in mine airways (Ramani, 1983)."

Dec 1, 1996

By J. D. Noll

The Mine Safety and Health Administration (MSHA) has promulgated rules to limit the exposure of metal/nonmetal underground miners to diesel particulate matter (DPM). These rules have resulted in many types of control tech­nologies being implemented including diesel particulate filters (DPF). The passive type DPF is the most desirable because it requires little maintenance and it regenerates while the vehicle is operating. One problem with passive DPFs is that many vehicles cannot develop the sustained exhaust temperatures needed to initiate DPF regeneration, and thus it is required that the DPF be catalyzed to decrease the temperature needed for regeneration. In some past studies, such catalyzed filters have been shown to cause an increase in the nitrogen dioxide concentrations in the exhaust, resulting in a potential health hazard. In this study, a lightly catalyzed DPF along with a fuel-born catalyst were employed to help reduce the DPM emissions from a 980F loader used for cleanup in a stone mine. After 30 days of use, the filter continued to regenerate successfully at the exhaust temperatures generated by this loader, substantially reduced DPM concentrations emitted in the exhaust, and did not cause a measurable increase in nitrogen dioxide levels that could be attributed to the device.

Jan 1, 2009

By F. L. Wideman

SPURRED by demands of a buoyant economy for mineral products, output from mines in the United States established a new record. Removal of waste material, necessary for the extraction of economic minerals, kept pace with mine production. Earth moving by these two activities exceeded 3 billion tons, an increase of 5 percent over that of 1963. Crude materials from which metal or nonmetal products were derived accounted for 75 percent of the total. The remainder, mostly worthless, was classified as waste. Changes in the minerals industry result from many causes. Technological trends and labor productivity are among several significant and interrelated indexes that assist in the analysis of the changes. Therefore, a. study of productivity is helpful in measuring technological growth in mining. Concepts of productivity tend to vary with the purpose for which the term is used; frequently, productivity is expressed in terms of units of output per unit of labor, such as tons of ore per man-hour or man-shift. Comparisons of levels of productivity for a group of products are usually made using composites of output. Data for all metal and nonmetal mines except gold, silver, mercury, platinum metals group, and sand and grave were used to compile the composite for determining productivity for 1960-64. Copper ore, iron ore, and phosphate rock are mined mainly by surface methods, but characteristics of the deposits and differences in processing the crude material affect production of the commodities. Therefore, productivity data for these selected segments of the minerals industry reflect the influence of physical conditions on the exploitation of them.

Jan 1, 1965

By Horace M. Lawrence, Edmund S. Leaver

"The sulphidizing filming of minerals in oxide ores as a preliminary treatment to aid their recovery by flotation is known practice. In this work the use of barium polysulphide does not appear to have been considered. A study of the properties of barium lead to the following comparative investigation of the sulphides and polysulphides of the alkaline and alkaline-earth metals. It is thought that barium polysulphide may prove to be a more satisfactory sulphidizing reagent than others now in use under conditions that favor the cheaper barium reagent.For the investigation two fairly typical oxidized ores of copper and lead were selected. The copper ore came from the Big Indian Mine in southeastern Utah, and assayed 3.8% Cu; the copper was present in a sandstone gangue mainly as the carbonates, malachite and azurite, with less than 0.2% as sulphides, or silicate. The lead ore is from the Tintic Standard mine in the Tintic district, Utah. It is typical of the oxidized lead-silver ores of that district; the lead is present in an oxidised form in a siliceous gangue, much: Uncolored by ferric oxide. The sample assayed 5.15% Pb and 11.3 oz. Ag.In addition to the results obtained in this investigation, there are included some results secured by Mr. J. B. Lain, consulting metallurgist of Reno, Nevada, on a sample of ore from the Chino Copper Co. The ore assayed about 1.7% Cu, of which about 0.25% was nonsuiphide."

Aug 1, 1925

By Kevin Connor

The mineral industry continued to be an almost negligible contributor to the country's economy as the Government continued its 1979 ban on any mineral exploitation for export; a policy initiated at the end of 1979. A national program had been underway since that time to map and inventory all mineral resources so as to permit future exploitation of mineral wealth in the beat interests of the country and its inhabitants. In March 1982, the British Sulphur Corp. Ltd., under contract to the Burundi Government and the International Bank for Reconstruction and Development (World Bank), began a feasibility study of Burundi's phosphate deposits at Matongo-Bandaga for potential commercial exploitation. The 1-year project effort was to define ore reserves, conceptually design mining operations and processing facilities, estimate capital and production cost, and develop a regional market and distribution survey. Work completed during the year comprised geological exploration and reconnaissance and 1,200 meters of core drilling. Reserves in excess of 5 million tons of ore-grade phosphate were estimated available for mining. Rare earth mineralization was associated with the primary apatite. The associated carbonatite within the rock matrix was preliminarily assessed to be of value as a raw material for the manufacture of cement. The contract effort was valued at $1.2 million? Matongo-Bandaga is located approximately 40 kilometers north of the capital city of Bujumbura and alongside one of the country's few paved roads.

Jan 1, 1984

By Charles D. Litton

Laboratory experiments were conducted to determine the responses of a prototype smoke detector and a commercially available photoelectric smoke detector to smoke particles generated from various combustion sources. The prototype smoke detector combines optical scattering measurements with ionization chamber measurements in order to reduce/eliminate nuisance alarms due to the presence of airborne dusts or diesel exhaust particles. The commercially available smoke detector is designed for use in harsh environments where airborne dust represents a major problem due to both nuisance alarms and detector contamination. In the experiments, the responses of the two detectors were measured when exposed to smoke particles from the exhaust of a diesel engine and from a variety of fire sources, including wood, coal, styrene butadiene rubber, and No. 2 diesel fuel. For the solid fuels, data were obtained for both smoldering and flaming combustions. This report describes the experiments, their results, and the use of these results as they apply to early-warning fire sensors capable of the rapid and reliable detection of fires in atmospheres that may or may not be contaminated by either airborne dust or the products produced from diesel engines.

Jan 1, 2008

By W. H. Ode

Low-temperature distillation tests at 200°, 350°, and 500° C. were made on a subbituminous coal from Boulder County, Colo., and a subbituminous coal from Weld County, Colo., in connection with a survey of carbonizing properties of American coals4/ and. investigations of their chemical and physical properties.5/ The coal represented by the sample from weld County was reported to give off combustible volatile matter at unusually low temperatures when placed on a fuel bed. The yields of tar and oil and the composition of the gas from this coal, as obtained in the distillation tests, did not confirm this report. These yields and the gas composition of the Weld County coal differed but little from those obtained from the coal from Boulder County. Both coals yielded tar and gas in amounts considered to be normal for coals of their rank.

Jan 1, 1937

By A. W. Khair, L. D. Gehl

"This paper describes the study of bit wear characteristics on three types of rock namely Tennessee sandstone, Berea sandstone and Indiana limestone. High content of quartz with quartz cement in Tennessee sandstone causes removal of material from the bit body and dam2ge to the tip of the bit resulting into excessive weight and height loss as compared to other two types of rock. The drum speed and water spray pressure do not contribute significant effect on bit wear. The polycrystalline compact diamond (PCD) tipped bits are more wear resistant than the ordinary tungsten carbide (WC) tipped bits, but, due to wider body of PCD bits, the wear rate increases particularly at greater depth of cut. INTRODUCTIONThe impact of bit-rock interaction during the cutting process in underground coal mines has always attracted the-interests of mining operators, researchers and the manufacturers. Coal cutting bears directly on airborne coal dust generation which causes ""black lung"" in coal workers. On the other hand, rock cutting generates frictional sparks causing face ignitions. The bit wear not only produces airborne rcspirable coal dust , but also affects the productivity, safety and economy. Hun and Evans (J) concluded that the point attack bits have greater ignition potential than the conventional wedge shaped bits. The results of a study (2) suggested that after 7% of weight loss, the bit should be replaced. In a survey study (3), it was found that the bit consumption of bit had an effect on the productivity and utilization of the continuous miners. The mining industry is yet to receive a solution which could provide them with optimum operating parameters for coal cutting machines in underground C9al mines.The study was, therefore, taken up to determine wear characteristics as influenced by the rock propenies and varying operating parameters. For the purpose of this study, three types of rock, Tennessee sandstone, Berea sandstone and Indiana limestone were used. The machine operating parameters included (i) drum speed, (ii) water spray pressure and (iii) bit type. Besides studying the wear characteristics, the effects of these parameters on the required cutting force, specific energy consumption, acoustic emission generation and bit temperature rise were also studied. Also, the preliminary experiments were performed to compare the bit wear between PCD and WC tipped bits."

Dec 1, 1995

By W. G. Pariseau

A U.S. Bureau of Mines case study of pillar recovery in high-grade ore near the Ross shaft at the Homestake Mine, Lead, SD, has demonstrated the usefulness of the finite-element method for evaluating shaft pillar mining plans and shaft stability. This report focuses on mine measurements and calibration of the two-dimensional computer model and is the second in a series of three Reports of Investigations describing the Ross shaft study. In this study, borehole extensometers and other instruments were installed to provide data for model verification and to monitor the shaft. Results of the recalibrated two-dimensional model (UTAH2) confirmed the premining stability evaluation. However, after mining began, concern was expressed because cracks and other signs of ground motion appeared at considerable distances from the area of active pillar mining. In part 3 of the study, an intensive three-dimensional modeling effort using UTAH3 was initiated. The results again showed that the observed effects were within expectations and that the shaft would remain safe. Three-dimensional analyses of alternative pillar mining scenarios indicated that more of the shaft pillar ore reserve could be recovered than previously thought.

Jan 1, 2010