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Laboratory tests were conducted by the U.S. Bureau of Mines to determine respirable dust reduction effectiveness of and interaction between face airflow and water sprays for a continuous miner. Increases in exhausting face ventilation from 3,000 to 9,000 cfm, in waterflow from 15 to 35 gpm, and in water nozzle operating pressure from 80 to 200 psi were evaluated. Results indicated that airflow had the greatest individual impact on reducing dust levels, with concentrations at return and operator sampling locations reduced by as much as 57% and 99%, respectively. Regression modeling was utilized to predict dust concentrations over the range of values tested for the control parameters. Interactions between the control parameters were significant and often defined an optimum level where further increases in that parameter failed to produce additional dust reductions. Increasing airflow to 8,400 cfm, waterflow to 25 gpm, and water pressure to 140 psi typically reduced dust concentrations at operator and return locations. Application of a control parameter above these levels can provide additional dust reductions if used in conjunction with appropriate levels of the other two control parameters. Otherwise, higher operator dust levels may result and can be attributed to increased rollback and/or airflow turbulence.

Jan 1, 2010

By P. F. Sands

This U.S. Bureau of Mines report reviews the state of the art in blind pneumatic stowing of backfill in voids in abandoned coal mines. It contains a short history of the development of pneumatic equipment in mining and four recent case histories of blind pneumatic stowing. Limitations of pneumatic stowing in terms of equipment wear, costs, backfill material, and methodology are discussed, and some new procedures and designs are reviewed. A bibliography covering pneumatics in mining is included also. This report provides background for the preparation of a Bureau test program in which the variables affecting the efficiency of pneumatic backfilling will be studied using a full-scale surface test facility.

Jan 1, 1990

By Dong-Wei Li, Tao Zhang, Diao Jiang, Zhou Wang

The feasibility of simultaneous vanadium extraction and phosphorus removal from vanadium-containing hot metal was demonstrated with laboratory experimental investigation.The effect of CaO addition on the distribution behavior of vanadium, phosphorus between basic vanadium slag and semi-steel as well as the influence of basicity on the leaching behavior of vanadium, phosphorus was particularly studied. Results show that vanadium oxidation ratio slightly decreases with the increase of basicity, but phosphorus oxidation ratio rapidly increases with the increase of basicity. The leaching of roasted vanadium slag with various CaO contents indicated that the optimal slag basicity for extracting vanadium was 1.5. The maximum leaching efficiency of vanadium could reach 84.02% and the sequence of vanadium leaching efficiency by using different leaching reagents was: 160 g/L Na2CO3 > 100 g/L NaHCO3 > 400 g/L (NH4)2CO3 > 5% H2SO4.

Mar 1, 2017

The addition of copper sulfate to mineral slurries in order to ?activate? sulfide mineral surfaces for enhanced collector molecule adsorption, and hence enhanced recovery via flotation, is a com-mon mineral processing practice. It has been established in a laboratory situation that the addition of CuSO4 in conjunction with xanthate collector increases the flotation rate of pentlandite as compared to the addition of collector alone. However, it remains unclear whether the addition of CuSO4has a similar effect within mineral processing circuits. We examine here the effect of pre-activation oxidation on the copper activation of pentlandite and monoclinic and hexagonal pyrrhotite. All activation experiments were carried out at pH 9 using a total solution content of copper ions equivalent to one monolayer (0.210 -4 moles, 110-4M). Copper loss from solution was extremely rapid in all cases with less than 10 % remaining after 10s. EDTA extraction and solution analysis clearly demonstrated that copper activation was via direct surface adsorption and not an ion exchange process, as is the case for sphalerite, and that most copper on the surfaces is in the form of Cu(I). ToF-SIMS analyses of the mineral surfaces subsequent to copper activation show increased surface oxidation on increased conditioning time prior to copper activation. However, there is a significant decrease in surface oxidation on comparison of samples that have otherwise been prepared in the same manner but where one has been exposed to copper solution rather than water. This suggests that copper activation stabilises the surface and reduces the propensity for oxidation. Regardless of the length of pre-activation oxidation time only Fe(III) (no Fe(II)-S) was observed by XPS analysis, indicating a highly oxidised surface layer dominated by Fe-O-OH species. The presence of Cu(II) on the mineral surface is indicative of the formation of Cu(II)-containing precipitates and indicates non-mineral specific activation resulting in increased recovery but lower grade. Mineral specific copper adsorption, as evidenced by the presence of Cu(I), is required to improve both grade and recovery. Prolonged oxidation prior to copper activation causes a reduction in the Cu(I) to Cu(II) ratio on the mineral surfaces as compared to either fresh surfaces or surfaces oxidised for 1 minute only. This strongly indicates that the copper activation process is less effective on highly oxidised surfaces.

Jan 1, 2014

By G. R. Hopkins, E. M. SEELEY

The number of natural-gasoline plants has shown a consistent decline in recent years, but the total capacity has increased steadily. The number of completed plants, as determined by a survey as of January 1, 1932, amounted to 959. Previous surveys of January 1, 1928 and 1930 showed 1,155 and 1,035 plants, respectively. Of the total plants on January 1, 1932, 859 were operating and 100 were shut down, compared with 999 operating and 36 shut down on January 1, 1930. The material gain in the number of inoperative plants in the last two years was probably due to the severe decline in prices of 1931. The low prices of 1931, which were approximately 40 per cent below 1930, made it virtually impossible for the majority of the independent plants, or plants not owned by a large integrated company, to operate at a profit. Accordingly, the majority of the plants removed from the list in 1930 and 1931 were owned by companies which were engaged solely in the manufacture of natural gasoline. The total daily capacity of the plants on January 1, 1932, amounted to 11,387,000 gallons, an increase of 871,000 gallons, or 8 per cent, in the two years 1930 and 1931. That the total capacity of the plants has increased while the number of plants has declined is due to the fact that nearly all the plants constructed in the last five years have been large plants. During 1931 the average total daily capacity of the operating plants was approximately 10,600,000 gallons, while the average daily production amounted to 4,944,000 gallons. This indicates that the plants operated during 1931 at 47 per cent of their capacity, compared with 58 per cent in 1930 and 61 per cent in 1929. Although more plants have been dismantled in Oklahoma in recent years than in any other State, it continues to rank first in number of plants. On January 1, 1932, there were 238 plants in Oklahoma, compared with 145 plants

Jun 1, 1932

1. ACKERMAN, C. L. The Binary System Manganese-Zinc. Ztschr. Metall., vol. 19, 1927, p. 200. 2. ADKENASY, P., AND KLONOWSKY, S. Über die Manganatschmelze. Ztschr. Elektrochem., vol. 16, 1910, p. 107. 3. AKTIEBOLAGET FERROLEGERINGAR (assignees). Method for the Manufacture of Manganese Alloys Poor in Carbon or Silicon or Else Manganese. British Patent 163262, Apr. 28, 1921; U. S. Patent 1480267, Jan. 8, 1924. 4. Method of Producing Manganese or Manganese Alloys Poor in Carbon or Silicon. British Patent 174923, Jan. 25, 1922.

Jan 1, 1934

By N. C. Saxena, S. K. Puri, A. K. Pal

The condition-based monitoring system is an important innovation for reducing the downtime of costly, heavy earth- moving machinery (HEMM). Vibration severity measurements were made on the HEMM located at the Gevra Project, the largest coal opencast project in India. Whenever the vibration severity levels exceeded the permissible limits, necessary actions were taken to replace the defective parts of the ma- chine. The systematic vibration monitoring of 120-t (132-st) dumpers, followed by corrective measures led to a substantial increase in component life (8.18% for an 445E Dressor and 28.44% for an MK-30 Unit Rig). The associated costs (including spareparts) were reduced by 21.55% and 25.74%, respectively. Because of the reduced downtime, savings for these two dumpers over the period from March 26 to June 25,1998, were of the order of Rs.26.47 (US$0.649) million.

Jan 1, 2000

By W. L. Acherman

Molybdenum, tungsten, and vanadium were found by the Bureau of Mines to possess generally superior chemical and galvanic corrosion properties in many aqueous corrosive media at temperatures up to the boiling point. The corrosion resistance of vanadium in certain solutions was further improved by alloying it with such metals as columbium, tantalum, and titanium. was susceptible to a type of crevice corrosion in mercuric chloride solutions, but no other instances of crevice corrosion were encountered. With few exceptions, molybdenum, tungsten, and vanadium were not adversely affected when coupled with dissimilar metals in galvanic corrosion experiments; in some cases one or both members of a couple were protected by contact. When exposed to aqueous ammonia spray at 60° C, all three metals were attacked, but they were moderately resistant in spray environments of substitute ocean water and ammonium dihydrogen phosphate.

Jan 1, 1966

By Oliver C. Ralston

Fluorescence is of growing interest to the mineral industry because certain minerals may be detected thereby and because, as shown in figure 1,4/ many minerals (natural or synthetic) are needed in tubes and lamps. The use of fluorescent lighting is expanding, and large numbers of lamps of many sizes and shapes are being made and used in works, factories, stores, offices, homes, and in photography. Fluorescent tubes, as distinguished from clear tubes filled with neon, argon, or other rare gases through which a current of electricity passes, fluoresce owing to specially, selected and prepared minerals placed in the tubes. Luminous chemicals and paints also contain special minerals and are used in similar applications; therefore, these also will be considered in this report. Although the quantity of minerals (in tons) that are used for fluorescent purposes is small, and probably will continue to be so, this use is significant because it exemplifies a requirement for "pure" minerals in which a trace of contaminant as" minute" as one part in ten million may distinguish between the acceptance or rejection of a particular material. This extreme purity makes synthetic minerals almost essential, and natural mineral's are now little used.

Jan 1, 1944

By Katsutoshi Komeya

Aluminum nitride(A1N) is a theoretically high thermal conductive ceramic, but is a poor sinterable one because of its covalent bond structure. The densification of A1N had to be done first. It was found in 1968 that rare earth compounds as yttria were an excellent sintering aids. Recently more improvement of conductivity was attained by following effects of yttria: (1) trapping of oxygen in A1N sources to form yttrium aluminates, (2)elimination of the aluminates by heating in carbo-reductive atmosphere. Consequently very high thermal conductivity of up to 270W/mK has been developed. Thus A1N applications for substrates and packages have been opened.

Jan 1, 1992

By P. A. Beck, W. D. Manly

In a recent note Sully and Head1 showed that the Cr-Fe sigma phase is isomorplious with the Cr-Co gamma phase, and that the lattice constants are also nearly identical. In a preliminary investigation of the ternary Cr-Co-Fe system at 800°C at this laboratory the above findings were confirmed, and it was found by microscopic techniques, using various etching reagents, that the two binary phases form an urinterrupted series of solid solutions with each other. These solid solutions occupy a straight narrow band which cuts across the 800°C isothermal section of the ternary system, connecting the two binary phases. A detailed investigation of the Cr-Co-Ni ternary system at 1200°C disclosed that here, too, the Cr-Co gamma phase extends deep into the ternary system in the form of a long narrow lip. The fact that this sigma type lattice is sustained even when well over half of the Co atoms in it are replaced by Ni atoms, with relatively little change in the Cr content, clearly indicates that Ni itself has a certain tendency to form the sigma phase with chromium. This tendency is hidden in the binary Cr-Ni alloys, where the sigma phase is not known to occur, but it becomes operative in the presence of a suficient amount of Co. The interpretation of these facts in terms of electron concentrations is rendered difficult by the uncertainty of our present knowledge of the valency electron structure of the transition elements in their alloys. However, Sully and Heal's results and the present work suggest that intermetallic phases with signla type lattice may occur more frequently in these little investigated alloys than heretofore suspected. In particular, it is expected that a similar phase may exist in the V-Co and perhaps in the V-Ni system, in analogy to the known sigma type phase in the V-Fe system, and that all these sigma type phases may form extensive solid solutions with one another.

Jan 1, 1950

A regular general meeting of the Canadian Mining Institute will be held in Vancouver, B. C., on Nov. 26-28. The Council extends a cordial invitation to all members of the American Institute of Mining and Metallurgical Engineers to attend.

Jan 11, 1919

By Giulio Rodrigues Altoé

Fibras de fique (Furcraea Andina) estão entre as lignocelulósicas naturais com grande potencial para utilização em compósitos poliméricos. O presente trabalho avalia a resistência ao impacto deste tipo de compósito com matriz epoxídica reforçada com diferentes percentuais de fibras de fique. As fibras foram embutidas sob pressão em mistura com resina epóxi DGEBA/TETA curada à temperatura ambiente por 24 horas. Os corpos de prova normalizados foram confeccionados com percentuais de até 30% em volume de fibras de fique alinhadas ao longo de todo o comprimento, estes corpos de prova foram então ensaiados em pêndulo de impacto Charpy e as superfícies de fratura analisadas por microscopia eletrônica de varredura, MEV. A resistência ao impacto aumentou substancialmente com a quantidade relativa de fibra de fique reforçando o compósito. Este desempenho foi associado à dificuldade de ruptura imposta pelas fibras bem como ao tipo de trincas resultantes da interação fibra de fique/matriz epoxídica que ajuda a absorver a energia do impacto.

Aug 17, 2017

By William A. Beck

Bauxite was discovered in the Springvale district in 1916. About 16, 000 tons was mined in the period 1916 to 1922, but no bauxite mining has been done since that time. The Bureau of Mines explored for bauxite in the district from September 5 to November 18, 1943. During the life of the project, the Bureau of Mines obtained mineral exploration agreements covering a total of 11,330 acres from 50 property owners. A total of 388 holes were drilled on five of these properties and 164 samples were taken and analyzed. The Springvale bauxite district includes an area of about 30 square miles in the northwestern part of Randolph County, Ga. The village of Springvale is in the west central part of the district, and Cuthbert is 8 miles southeast of it (fig. 1).

Jan 1, 1949

A permanent exhibition of mining machinery has just been opened in the Grand Central Palace, New York City. The exhibits include: Aerial tramways, amalgamation, assaying and laboratory appliances and supplies, blast furnaces, coal, coal-breaker plant, coal excavation, coal products, compressed-air plant, concentrating, crushing, cyanidation, distillation, drainage and pumping, drilling, earth excavation, electrical supplies, explosives, fire prevention, flotation, general supplies, hoisting, hygiene, welfare, iron products, leaching, mechanical conveyors, metal products, natural gas, petroleum, petroleum products, electric, steam, hydraulic, gas, air, and internal-combustion engines, power machinery, preparation of coal, pumping, refining, roasting, rock excavation, rotary drilling; boring, safety appliance, screening and washing, sizing and classifying, smelting, storage of coal, storage of petroleum, surface transportation, surveying, underground timbering, underground trans-port, ventilation, mine. This exposition is operated by the Merchants and Manufacturers Exchange of New York for the purpose of showing under one roof all lines of machinery and mechanical appliances. As for as possible, the exhibits will be shown in operation. The Advisory Committee is as follows: General Howard R. Ward and H. C. Parmelee. Coal and Coke.-Prof. H. H. Stoek, Samuel A. Taylor, Edwin Ludlow. Petroleum and Gas.-Frederick G. Clapp, Ralph Arnold.¬ Extraction of Metals.-Charles W. Merrill, E. Gybbon Spilsbury. Refractories.-Kenneth Seaver.

Jan 12, 1919

By John L. Bolles

The Phelps Dodge Corporation's Morenci Concentrator includes facilities for coarse crushing, fine crushing, grinding, flotation, tailing, disposal, concentrate filtering, and drying. The Morenci Concentrator daily throughput is in excess of 60, 000 tons. The ore milled is mainly a medium-hard monzonite porphyry in which the principal sulfide minerals are chalcocite and pyrite. The ore is transported by rail from the Open Pit Mine to the primary crushing plant located at the concentrator site. Ore is side-dumped from 80¬ton railroad cars into a sixty-inch gyratory crusher. The ore is then conveyed to a. 12, 000 ton coarse ore storage bin. Fine crushing is accomplished by four parallel lines of conventionally stacked crushers in open circuit. Each unit consists of one seven-foot standard cone followed by two seven-foot shortheads. Ti% product of the fine crushing plant is distributed by two tripper cars across a fine ore storage bin. The crushed ore is then fed by variable speed belt feeders into thirty parallel, single stage, closed circuit grinding units. Each of the 30 grinding units consists of one 6' x 23' conditioning drum, one 10' x 10' ha l mill and two 54" duplex spiral classifiers as principal equipment. The dry ore is fed into the conditioning drum with water to dilute the ore to a slurry of approximately 78% solids by weight. An aqueous solution of ammonium sulfide is also added to the conditioning drum. The ammonium sulfide primarily acts as a sulfidizing agent. The ore slurry containing the naturally occurring sulfide copper minerals and the sulfidized copper minerals discharges into the feed scoop box of the ball mill, where milk of lime, collector and-.dilution water are added. The ball mill product slurry is gravity fed: to the classifier pool where water is added to obtain the desired classifier overflow product

Jan 1, 1977

By D J. Murray

This paper outlines the principles of friction hoisting and the components involved, and gives a description of a specific mine hoist. Friction hoisting is compared with conventional drum hoisting, and the depth of shaft at which friction hoists become more economical than drum hoists, with respect to power consumption, is determined. Introduction T HE purpose of this paper is to outline the principles of friction hoisting, to describe the components and to show the advantages of multi-rope friction hoisting. Some calculations are made to show that the power requirements and the initial costs of friction hoists are less than those of conventional drum hoists, once a certain depth of shaft has been reached. The use of multi-rope friction hoists is gradually superseding the employment of the conventional drum hoist in many parts of the world. It results in heavier payloads from deeper levels, an increase in shaft safe-ty and a more compact installation for protection against adverse weather conditions. It was observed that where drums and friction sheaves exceeded 30 feet in diameter, a number of mechanical disadvantages were being experienced;

Jan 1, 1965

No true conception of the Park City mining district can be obtained without first giving consideration to the part it has played as a consistent producer of mineral wealth. Its position in this regard is almost unique in the annals of a lead silver camp. For over fifty years it has been a continuous producer of lead and silver and for twenty years it has added to the world's supply of zinc. Few camps with its productive history are so little known to the mining fraternity for the reason that its life has never been punctuated by periods of "boom" which serve to attract general attention, neither has it been the field of operation for promoters who temporarily focus attention upon their scene of action. Its history is one of legitimate mining operations. These were at first carried on by a number of smaller companies. A period of consolidation followed and at the present time the entire production of the camp is in the hands of two major companies and one smaller company. These are flanked by a number of prospecting properties, which are at this time actively engaged in the search for ores and later events will doubtless put some of them in the producing class.

Jan 1, 1925

By Donald P. Schlick

This Information Circular presents a brief historical digest of the early attempts of the Bureau of Nines and the U.S. Public Health Service to establish coal mine dust exposure standards. It reviews current, accepted standards of the United States as well as available standards of other countries.

Jan 1, 1971

By John C. Edwards, Gene F. Friel, John J. Opferman, Robert A. Franks

A series of diesel fuel fire experiments were conducted in the Pittsburgh Research Center's Safety Research Coal Mine (SRCM) to determine products-of-combustion (POC) spread rates along a single entry under zero imposed airflow conditions. Six experiments with an average fire intensity of 330 kW and three experiments with an average fire intensity of 30 kW were conducted in a 1 80 m long entry which had an average 2 m height and 4 m width. POC spread rates were measured by the response time of diffusion type CO detectors, positioned at 30 m intervals, to CO concentrations 5 ppm above ambient. For the 330 kW fires, average POC spread rates of 0.22, 0.13, and 0.06 m/s were determined at 30.60, and 90 m distances from the fire. For the 30 kW fires these average spread rates were reduced to 0.08, 0.04, and 0.04 m/s. The measured maximum roof layer temperature 30 m from two of the 330 kW fire was 30 and 36"C, which is less than the 57°C alarm point of a typical mine thermal sensor. It was determined that smoke detectors can be more effective for mine fire detection than CO detectors. The experimentally determined POC spread rates can be used to provide guidance for specification of sensor spacing to improve early fire detection at zero or very low air flows.