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By H. Polat, Q. Hu, M. Polat, S. Chander

"The electrostatic charge on spray droplets of ionic surfactant solutions and coal particles was measured and the results were correlated with the dust collection efficiency. When various surfactant were added, the magnitude of the droplet charge increased significantly and it was observed to be a function of surfactant type and concentration. The concentration of maximum droplet charge coincided with surfactant concentration where maximum collection efficiency was observed for these surfactants. Particles of coal also carried substantial amount of charge magnitude of which seemed to be a function of coal rank.Based on the results presented in this paper, it was concluded that ionic surfactant primarily act as a strong electrostatic charge inducer for droplets. Due to interactions between these highly charged droplets and naturally charged particles, the efficiency of droplet-particle collisions play a primary role when compared to the wetting and engulfment phenomenon which could only follow a successful collision. INTRODUCTIONWater spray are widely used to suppress airborne dust in mine atmospheres (Walton and Woolcock, 1960; Kobrick, 1970; Hamilton, 1974; Jayaraman et al., 1986). Several investigators have considered the use of surfactants to enhance the effectiveness of water sprays especially for difficult to wet particles such as those of coal (Glanville and Wightman, 1979). The capture of dust particles by water droplets involves droplet-particle collisions, adhesion of particles to droplets, and engulfment of particles into droplets. Surfactants affect these sub processes through their influence on droplet charge, surface tension, and wetting. The last two mechanism have been thoroughly studied in recent years (Walker et al., 1952; Cohen and Rosen, 1981; Glenville and Haley, 1982; Chander et al., 1988; 1991). However, little attention has been paid to the role of electrical charge on particles and droplets on the collision and adhesion of spray droplets and dust particles."

Nov 1, 1995

By W. W. Agey

The Bureau of Mines examined and tested the rhodonite deposits of the Silverton lead-zinc district, San Juan County, Colo., as a possible source of domestic manganese. Exploration and development work by several mining companies and preliminary reconnaissance of the area by Bureau of Mines engineers indicated the presence of extensive manganese resources in the form of rhodonite. This report summarizes the results of laboratory beneficiation tests made on samples of different type and grade material obtained from surface and underground exposures of seven veins in the district. Surface and underground examinations revealed the presence of several prominent veins that could be traced up to 2 miles for a single vein along the surface. The principal veins average about 50 feet in width and apparently carry rhodonite to considerable depth. Underground samples were taken from the Sunnyside, Silver Queen, Washington, Independence, and Scotia veins. Samples also were taken from surface exposures of the Sunnyside Extension and Hidden Treasure veins.

Jan 1, 1962

By H. J. Heinen

The Bureau of Milts studied repetitive batch electrowinning of molybdenum from molybdic oxide ) to determine the effects upon the electrolyte life, purity of metal product , and overall cell performance. The electrolyte consisted of 54.0 weight-percent sodium tetraborate (Na2B407), 23.6 weight-percent sodium chloride (NaC1), 14.9 weight-percent sodium fluoride (NaF), and 7.5 weight-percent Mo03. The feed materials were pure and technical-grade Mo03. Electrolysis was conducted at l,000° C in a graphite cell in an atmosphere of air and carbon oxides. Electrolyte degradation did not occur during repetitive winning of molybdenum from pure Mo03 in an 8-day (5,400-ampere-hour) period of operation. Electrowon metal contained <0.1 percent total impurities. The electrode configuration is a key factor in the direct conversion of technical-grade Mo03 to metal by repetitive cyclic electrolysis. The best configuration found was a cathodic crucible and a central anode. Metal purity of 99.8 percent and a current efficiency of 91 percent were maintained until the combined impurity buildup the electrolyte reached 4.7 percent silicon, l.0 percent aluminum, and 0.6 percent iron. One pound of molybdenum was produced per 1.5 pounds of solvent salts employed. About 25 percent of the initial NaCl and NaF contents of the electrolyte were lost owing to volatilization and crucible penetration.

Jan 1, 1966

By George H. Holmes

This paper , which describes mining methods and milling and manufacturing operations at the gypsum property of the Blue Diamond Corp. , is one of a series on mining methods and practices being prepared by the Mining Division of the Bureau of Mines . The property comprises about 4,000 acres and is in secs . 30 , 31 , 32 , and 33 , T. 21 S. , R. 59 E. , and secs . 5 , 6, 7 , 8 , and 9 , T. 22 S. , R. 59 E. , M. D. B. and M. , Clark County , Nev . , approximately 23 miles by paved highway southwest of Las Vegas , Nev . ( fig . 1 ) . This circular summarizes the history of company operations , describes physical features , labor and living conditions , and the geology . The method of exploration is outlined , and the section on mining methods contains descriptions of open - pit and underground systems , including loading and transportation methods . The crushing plant and tramway are described , as well as plaster-mill and board -plant practices . The boiler plant and organization are described , and wage scales are contained in the concluding section of the circular .

Mar 1, 1950

By Charles D. Litton

This Bureau of Mines report presents a discussion of the essential components of pneumatic monitoring systems and their associated functions. Design criteria are presented which can be used for the design and fabrication of pneumatic monitoring systems having total system response times on the order of 15 to 30 min. To illustrate the utility of these design criteria, two detailed design examples are presented,

Jan 1, 1983

By Leonard Obert

Subsidence to surface occurs in a large proportion of underground mines. Preliminary to any indication of subsidence on the surface, there is usually a breaking up and sloughing of the cover into the mine opening which, in a period of time ranging from minutes to many years, progresses to the surface, This process is referred to as subsurface subsidence. In many mining operations, information regarding the process of subsurface subsidence is important, For example, if there are buildings or other improvements on the surface, or if the direction of the subsurface subsidence might threaten other underground workings--such as shafts--or if the subsidence might be progressing in a direction which would fall outside the anticipated subsidence limits, the problem could assume special significance.

Jan 1, 1961

By G. W. Weems

The Bureau of Mines combined preconcentrating techniques and mass spectrometry to develop a parts-per-billion general analysis of impurities in helium. The impurities are preconcentrated using a Bureau trace-impurity analyzer; 35-mm Hg pressure of helium is left in the concentration trap to sweep the impurities into the mass spectrometry and provide a 10-mm Hg sample pressure.

Jan 1, 1966

By W. R. Huff

Yield stress and plastic viscosity values, determined from shear rate-shear stress relationships, were found to be a linear function of coal concentration for coal-water slurries containing 40, 45, 50, and 55 weight-percent of powdered coal. In the laminar region, the flow is described by an equation derived from the fact that the square root of the shear stress varied linearily with the square root of the shear rate. In the turbulent region, the friction factor was found to be inversely proportional to the velocity to the 0.12 power.

Jan 1, 1965

By Milton H. Fies

The dedication of thin building, establishing a station of the U.S. Bureau of vines at the University of Alabama, bristles with significance and challenges the wisdom and courage of the people of this State. Here is united, in common aim, the Engineering School of our State University, recognized for its competency and usefulness, and the Federal Bureau of Mines. The Bureau is one of the most effective arms of our National Government. It outranks in accomplishment, measured by practical scientific contribution, any like governmental organization in all the other nations. It possesses none of the characteristics of many other bureaus of government which have created popular bias. Here is one Bureau devoid of political suggestion or aim with a personnel zealously devoted to labor in scientific re¬search - an organization marked by practical accomplishment, alleviating many of life&apos;s burdens, raking easier life&apos;s pathway, and unerringly pointing to life&apos;s possibilities.

Jan 1, 1936

By Fred L. Bishop

This paper describing the methods employed in the purchasing and supply departments of the Miami Copper Co., Miami, Ariz., is one of a series being prepared for and published by the United States Bureau of Mines on office practice in mining operations. GENERAL DESCRIPTION The Miami Copper Co.&apos;s plant is located about 1 mile from the town of Miami, in the Globe-Miami Mining District, Gila County, Ariz. The property consists of a complete mining plant, concentrator, high-pressure steam power plant, and many other attendant structures. In normal times the company employs about 1,500 men, and mines and mills about 6,000,000 tons of ore annually.

Jan 1, 1932

By Geo. S. Krueger

This paper, describing mining methods and costs at the Judge mine Park City, Utah, is one of a series being prepared by the Bureau of Mines on mining practices in the United states. ACKNOWLEDGMENTS The writers acknowledge the assistance of E. D. Gardner, supervising engineer, Southwest Experiment Station, Bureau of Mines; Paul H. Hunt, mine manager, Park Utah Consolidated Mines Co.; Wm. Osika, chief mine accountant; and Eric Neilson, assistant master mechanic of the mine.

Jan 1, 1938

By Chas. F. Jackson

The annual reports of the supervising engineering of the nine sections comprising the Mining Division are assembled in the following pages and constitute the annual report of the division. In planning activities, the aim is to adapt them to changes in conditions, in the needs of the mining industries, and in the public interest; those current activities that contribute most to problems of present concern are emphasized, investigations of less immediate importance being recessed, if necessary.

Jan 1, 1940

By Chas. F. Jackson

The annual reports of the supervising engineers of the nine sections comprising the Mining Division are assembled in tie following pages and constitute the annual report of the division. In planning activities, the aim is to adapt them to changes in conditions, in the needs of the mining industries, and in the public interest; those current activities that contribute most to problem of present concern are emphasized, investigations of less immediate importance being recessed, if necessary.

Jan 1, 1940

By N. E. Hanna

The current Bureau of Mines active list of permissible explosives includes 124 brands. Thirteen are gelatinous and the rest are the more commonly used granular ammonium nitrate type. The list of permissible blasting devices comprises five Cardox models.

Jan 1, 1965

By N. E. Hanna

The current Bureau of Mines active list of permissible explosives includes 124 brands. Thirteen are gelatinous and the rest are the more commonly used granular ammonium nitrate type. The list of permissible blasting devices comprises five Cardox models.

Jan 1, 1965

By J. W. Thompson

"The Republic of Colombia on December 30, 1919, enacted a new petroleum law. The Act is expressly limited to mineral oil, natural gas, bitumen, wax and fossilized resin and to asphalt intended for export.The law is not only intended to encourage local investors, but to attract foreign capitalists for oil development. Provision is made for a special edition ion of the law in such languages as the Government may deem necessary to give it extensive circulation within the country and abroad. The published editions must contain the provisions of the law relating to alienship and naturalization.All public lands, or what are termed unclaimed lands, are open to flee prospecting for the purpose of discovering the deposits named in the law, A prospector must obtain from the Government a, license which binds him to deliver to the Government topographic plans of the lands prospected, together with reports of their prospective yielding capacity. This license does not vest the li¬censee with any preferential right for contracting or leasing and may be drawn by the Government at any time.If a discovery is made by a licensee of any of the deposits named and he desires to exploit the same, he must present a memorial or application to the Ministry of Public Works, stating:- (a) the location and municipal district in which deposit beds are found; (b) boundaries of the zone of exploitation, which shall not be more than 5,000 or less than 1,000 hectares; (c) the names and nationality of all persons for whom the lease is sought and the action and time within which,they propose to make the exploitation; (d) the name of the corporation and its legal representatives with their residences; (e) if an alien, he must state his willingness to comply with the law relative to alienship and naturalization; (f) agreement to abide by all of the provieions of the law with regard to Government supervision, payment of taxes, rate of lease and causes of forfeiture; (g) the rate of rent or royalty that the applicant offers to pay, together with any other circumstances that may make the proposed lease advantageous to the Nation."

Apr 1, 1920

By Robert W. Geehan

The Bureau of Mines has been developing deposits of critical and essential minerals in the United States since 1939. A preliminary examination of the Union lead mine was made in November 1944 and January 1945 by W. T. Benson, a Bureau of Mines engineer, who recommended development by diamond drilling. The Bureau conducted a drilling project at the mine from February 12 to May 16, 1947. The property is in sec.12, T. 17&apos;N., R. 19 E., Mount Diablo Base and Meridian, in. southern Washoe County, Nev., about 15 miles south of Reno. The Union lead mane, also known 4s the Commonwealth mine, has been an intermittent producer of zinc-lead-silver ore since 1860. During World War II, ore was shipped to smelter& near: salt Lake City, Utah. The Bureau drilled 21 diamond-drill holes having a total length of 1,549 feet and 20 long percussion-drill holes with a total length of 359 feet. The program was designed to test for horizontal and vertical extensions of the ore body and to prospect for parallel ore bodies. As a result of this program, extensions of the ore zone were established, but no parallel ore-bearing structures were found. The areas drilled were limited by drill sites available.

Jan 1, 1950

By H. W. Kilau

The Bureau of Mines evaluated synthetic fluorspar as a substitute for natural fluorspar flux in basic cupola ironmaking. The synthetic fluor-spars tested were prepared from waste fluosilicic acid generated during the processing of fluorapatite ore. The cupola trials showed the synthetic products to be the equivalent of natural fluorspar from an operational standpoint. However, wet scrubber sampling showed that substantial losses of volatilized fluorine occurred from the cupola during operation. The losses during synthetic fluorspar trials considerably exceeded those from natural fluorspar trials. Laboratory viscosity testing, using a high-temperature rotational viscometer, confirmed this finding and indicated that fluorspar volatility in slags is related to slag basicity. Synthetic fluorspar is accordingly recommended more for highly basic cupola operation (>1.3 basicity) than for neutral or acid operation, because of the increased potential for pollution and baghouse filter detezioration"

Jan 1, 1989

The Bureau of Mines equipped a longwall shearer with a water-jet-assisted cutting system and measured dust levels during the cutting of a simulated coal block. The block was cut dry, at a conventional water spray pressure of 190 psi, and with water-jet-assisted cutting pressures ranging from 1,000 to 6,000 psi. At water pressures of 3,000 psi and higher, dust concentrations were reduced by as much as 85 pct via water-jet-assisted cutting in comparison with conventional water sprays. This reduction was achieved without any increase in the water flow rate.

Jan 1, 1986

By C. A. Rhoades

The spillage that accumulates under conveyor belt lines presents a possible fire and explosion hazard fomiinqjetsoruiel, especially to those who must clean up the spillage. The U.S. Bureau of Mines conducted research to reduce this hazard by identifying and investigating the parameters affecting the efficiency of conveyor belt cleaning. The amount of material carried back under the conveyor and the wear rates of metal cleaning blades decreased with increasing blade-to-belt pressure to a limiting value, after which the carryback and wear rates remained essentially constant. The optimum blade-to-belt pressure was found to be 11 to 14 psi for the research conveyor system. Greater pressures increased the blade-belt friction without improving either cleaning or blade life. The modes of blade wear were three-body abrasion and slurry erosion caused by the sand-lime test mixture. Wear rates were reduced by increasing the metal hardness, opti-mizing the pressure, and removing conveyor belt imperfections. Corrosion was not observed to affect the wear of various steels in tests of less than 34 h. The results of this study should allow mine operators to run their conveyors under conditions that will maximize cleaning and minimize equipment wear.

Jan 1, 1989