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By William J. Campbell

One of the principal objectives of the Bureau of Mines program for developing super refractory materials is to obtain fundamental data on the physical properties of refractory oxides. This particular investigation obtained accurate thermal expansion coefficients for alpha alumina and evaluated, critically, those coefficients with other published values. High-temperature X-ray diffractometer measurements, by the Bureau, showed that alpha alumina expands anisotropically with expansion parallel to the c axis approximately 10 percent greater than parallel to the a axis. Thermal expansion characteristics of four different alumina samples were determined up to 1,200° C.; the results are presented in both tabular and graphical form. The combined random and systematic errors in the measurements are considered less than 3 percent above 500° C, and approximately 2 percent at 1,000° C. No differences in expansion were observed between the samples or between the heating or cooling cycles.

Jan 1, 1961

By D. N. Tallman

The electrokinetic properties of MgO have been utilized to simultaneously filter suspended solids and remove trace amounts of dissolved heavy metals from synthetic mine water. Greater than 95 pct removal of metals from influent at neutral pH containing 1 to 6 mg/L of dissolved Cd, Cu, Mn, Ni, and Zn can be routinely achieved by filtering through a granular bed of MgO at flow rates typical of rapid sand filtration (0.3 cm/s). Filtrate concentrations of most metals can be maintained below 0.1 mg/L for 160 bed volumes or more loading. The more mobile metals (those with larger solubility products) are more difficult to remove, and are strongly bonded to the MgO granules so that chemical stripping with chelating agent is required to clean the bed. Less mobile ions are easily removed by the filter and are effectively stripped by conventional filter backwashing. The fraction of metals recovered by chemically stripping the loaded MgO filters correlates to the zero points of charge of the metals. This process may be applicable to removal and recovery of trace amounts of heavy metals in mine drainage that is partly neutralized by liming. Also, since many of these metals are critical and strategic, the technique can be adapted not only to recycle process water from mineral and milling waste streams, but also to reclaim their metal values.

Jan 1, 1986

By J. A. Eisele

The Bureau of Mines is investigating the recovery of alumina from domestic nonbauxitic resources, including anorthosite. The United States has large reserves of anorthosite, but its aluminum content is less than 50 pct soluble in acid, unless a source of fluoride is added to the acid. A flowsheet that includes leaching with HCl and fluoride followed by crystallization of AlC13.6H20 from the pregnant liquor by HCl gas injection was designed. Approximately 90 pct of the aluminum values were recovered from the anorthosite when a ratio of 0.14 mole of fluorine per mole of aluminum was used. Sodium chloride is cocrystallized with the A1C13.6H20 but is removed by water washing of the Al203 product. A material balance is given based on results of laboratory studies of the unit operations.

Jan 1, 1983

By F. H. Nehl

The U.S. Bureau of Mines investigated the selective electrowinning of Ag and Au from cyanide solutions contaminated with Cu with the goal of decreasing the amount of Cu codeposited. Decreasing Cu codeposited will reduce refinery costs. Direct current was applied to the cell in pulsed and square wave voltages at 0.070 A?h per 150 mL of solution. Times tested for each cycle ranged from 1 to 10,000 ms. Graphite, lead, and stainless steel were evaluated as electrode materials. Square wave electrowinning at 70° C gave the best separation of Ag and Au from Cu. Applying 2.5 V during the duty cycle, 0.0 V the rest of the period, a duty cycle of 10 to 30 pct, and a period of 100 to 1,000 ms gave the following results: Ag concentrations decreased from 34 to 0.1µg/mL, Au concentrations decreased from 54 to 0.2 µg/mL, and Cu concentrations remained almost constant at 560 µg/mL.

Jan 1, 2010

By H. H. Schrenk

[There is a need for method of determining: benzene vapor in air which is simple and accurate and suitable for making industrial hygiene surveys. The most widely used method in this country is the modification of the Elliott and Dalton6/ procedure. This depends on the nitration of the benzene to reduction to phenylenediamine with all excesses of standard titanous chloride; solution, and titration with e standard ferric ammonium sulphite solution. This method has the disadvantages of being what time consulting: and cumbersome it requires considerable apparatus, and a special modification is necessary in the presence of toluene.]

Jan 1, 1935

By Louis C. Srichta

The rapid depletion of known high-grade ore deposits of the Tri-State district and the recognized need for development of additional reserves, together with increased interest in open-pit mining of low-grade zinc-lead ores led to Bureau of Mines examination of several abandoned mining areas for possible deposits adapted to strip mining. Examination of the North Empire tract in Cherokee County, suggested that mineralized zones contiguous to previously mined 2e deposits presented probabilities of meeting the requirements for an open-pit mine - hence the tract was selected for further investigation by churn drilling. The zinc-lead deposit on the property is in a sink-hole structure that has been subjected to intense deformation and silicification. Numerous shafts, mine dumps, and surface caves are evidences of exploitation of an extensive area. The reported active mining period was 1895 to 1905. No production records are available, but it is generally stated locally that the value of the mill products exceeded $2,000,000 which represents considerable production, considering the low metal prices of that epoch.

Jan 1, 1950

By Donald W. Mitchell

Certification tests for urethane-foam systems and techniques for apply-ing foam safely in mines are described. Fire hazard from foam exists if flame propagates beyond the ignition source or penetrates the foam. Foam that passes the certification tests can be applied on stoppings, continuous sections of ribs of relatively wide passageways (with no foam on the roof), short sections of roof such as overcasts, roof cavities, and intersections (with no foam on the ribs), and between buntons on one wall of a shaft. Foam on the ribs and adjoining roof presents a fire hazard. Stoppings covered with foam passing the certification tests are resistant to penetration of heat, flame, and smoke than similar stopping without foam. Flame propagation can be arrested by water sprays. Spontaneous ignition of foam can be prevented.

Jan 1, 1966

By G. Asai

The purpose of this Bureau of Mines investigation was to determine the properties of arc-melted iron-chromium alloys ranging in chromium content from 12 to 50 wt.-pct. Alloys were prepared by consumable-electrode arc melting of electrodes composed of high-purity chromium and high-purity iron. Alloys were fabricated to rod and sheet, and the following data were obtained: Electrical resistivity, hardness, tensile strength, and impact strength at room temperature; and creep-rupture life at 650° C. (1,200° F.). As the chromium content of the annealed alloys varied from 12 to 50 pct., the properties varied as follows: The electrical resistivity increased proportionally from 41 to 53 microhm-cm,; the Rockwell hardness varied from A 38 to A 58; the tensile strength ranged from 52,000 to 96,000 p.s.i.; the impact strength of V-notched charpy specimens varied from 140 to 405 ft.-lb., and the 100-hour creep rupture life at 1,200° F. varied from 5,000 to 16,000 p.s.i.

Jan 1, 1962

By H. H. Schrenk

There is a need for a method of determining benzene vapor in air which is simple and accurate and suitable for making industrial hygiene surveys. The most widely used method in this country is the Smyth modification of the Elliott and Dalton procedure. This depends on the nitration of the benzene to m-dinitrobenzene, reduction to phenylenediamine with an excess of standard titanous chloride solution, and back titration with a standard ferric ammonium sulphate solution. This method has the disadvantages of being somewhat time-consuming and cumbersome; it requires considerable apparatus, and a special modification is necessary in the presence of toluene. Recently Cook and Ficklen have published a method based on the oxidation of benzene with hydrogen peroxide in the presence of iron salts. This method requires the use of solid carbon dioxide to freeze out the benzene. The reaction Which produces the color is complex; and only approximate quantitative estimations can be made, except in a very narrow range.

Jan 1, 1935

By Thomas C. Atchison, Joseph M. Pugliese

Six explosives were compared by measuring their strain- producing abilities in limestone . Peak strain , e , varied with scaled distance , R/Ro , according to the following equation : € = Kc (R /R 。)- ". The distance exponent , n , was a constant of the rock and did not depend upon explosive . The strain intercept , Ke , increased with increasing detonation pressure of the explosive . The strain intercept also depended upon the explosive- to - rock impedance ratio . For impedance ratios from 0.53 to 1.38 , the strain intercept was approximately proportional to the medium stress , Pn , as calculated from the explosive detonation pressure , P , and the explosive - torock impedence ratio , Z , by the simple elastic theory relation : P = 2P / ( 1 + Z ) . PD However , the data indicated that , at lower values of impedance ratio , the strain intercept is relatively larger than would be expected from the simple elastic theory . The results presented provide a simple method for predicting the relative effectiveness of different explosives in breaking limestone from the detonation pressures and characteristic impedances of the explosives .

Jan 1, 1964

By Edward Roberts

This is a progress report of an investigation by personnel of the Bureau of Mines from June to September 1951 to introduce preservative chemicals into growing timber. It also describes in detail the impregnation process, known as the collar method, developed by the United States Department of Agriculture2/ Twenty-eight trees were treated by this method, and a complete record was kept of each individual tree and of each timber cut from it. These timbers have been placed in a coal mine, and their tendency to decay is compared to that of adjacent untreated sets. Although several years will be required before final conclusions can be drawn, this report explains the appearance and encouraging results of the treated timber to date. Also included are some comparative costs of untreated timber, treated timber by the commercial pressure method, and treated timber by the collar method. INTRODUCTION In the hope of increasing the useful life of cut timber, experiments to impregnate growing trees with wood-preservative chemicals by utilizing the natural flow of sap have been carried on for centuries. None of the various methods used in these experiments has ever gained any widespread use because they have been commercially impractical.

Jan 1, 1953

By H. P. Greenwald

[For sarno years past the Safety in Minbr. Resaarch J30ard of Great Bri tr-dn ha:1 been making ar.. intensive Gearch for, traterials that \.'ould be 1!\ore ef-ficient than rock dust and th t 'could l1eplace it Jholly or in El:}rt as a muans of prevEll'ltine the propa 'tion' of 'c63.1~dust exnlosions in. mines21 In the course of this \o.'ork several rock c.ur--ts md numerous inorganic compounds I,/ere tested. The result w place incombus.ti ble substFlnces in two main groups~ (1) r.:ho se who sa effect' in suppre aeina Jlihe cor.lbustion of coal dUDt i 0 pro-]

Jan 1, 1940

By [F. P. ] Stambaugh

Results of research on the hydrothermal precipitation of zirconium oxide from the Bureau of Mines' zirconyl chloride-sulfate strip liquors indicate that nuclear grade material can be prepared by this process. Greater than 99% of the zirconium value can be precipitated at 250-260°C in short (5-10 minutes) reaction time without consumption of acid value of the liquor. Thus, precipitation of zirconium dioxide on a continuous basis, i.e., the zirconium dioxide is precipitated in a continuous mode of operation by pumping the strip liquor through a heated pressurized reactor and recycle of the acidic (spent) liquor to the process stage are favored. The results of accompanying studies of liquod/solid separation, product washing and dewatering, product purity, and chlorination of the product are presented and discussed.

Jan 1, 1980

By Walter E. Lewis

Ventilation-air-heating plants are in use at several iron mines on the Menominee Iron Range, Iron River, Mich. Many of the mines are exceptionally wet; during winter months, when fresh air is forced down the wet air shafts into the mine, it is usually necessary to heat the fresh air to above freezing so that the openings will not be closed by ice. The problem of ice closing air shafts has been solved by the practice of reversing the air current before the openings have become completely closed. This procedure involves drawing warm air from the mine up the usual down-draft air shaft. The M. A. Hanna Co. has found, at some of their mines on the Menominee Range, that it is more convenient to heat the below-freezing air rather than reverse the air current. Intermittent freezing and thawing of ice that has formed in the air shaft tends to loosen the wall rock, requiring major shaft repairs. The openings are kept free of ice the year around by heating the fresh air during periods of below-freezing weather. Table 1 shows the monthly minimum moan, maximum mean, and mean temperatures for the Iron River area. Under normal conditions of temperature, the furnaces are fired in November and usually are not allowed to go out until April of the following year.

Jan 1, 1951

By James C. Barker

In 1981 and 1985-1986, the Bureau of Mines conducted orientation studies of marine placer platinum-group metals (PGM). PGM are derived from the Goodnews Bay ultramafic complex and magnetic surveys show that the complex extends offshore at least four mi. The present seafloor was an emergent foreland as recently as 8000 years ago. High-energy ocean processes are transporting and depositing sediment such that PGM-bearing materials are reworked and later masked by barren littoral drift. Exploration targets include 1) placers formed since present transgression began, and 2) ancient marine and drowned fluvial deposits. Additionally, there is evidence of PGM solution transport and accretion. At least minor values of PGM in Recent lag-type placers and possible submarine strands are concentrated along an offshore scarp incised through glacial deposits into the preglacial surface between Flat Cape and Red Mountain. Other Recent PGM-bearing features include Flat Cape shoal, Chagvan Bay, Salmon River delta, and modern beaches. Ancient placers include possible N-S fluvial systems 2 to 3 mi offshore, a nearshore scarp 50 ft below sea level, and strands adjacent to projected ultramafic bedrock slopes. The existance of ancient placers is dependent on depth of glacial erosion. SEM studies show PGM are principally isoferroplatinum and osmiridium, with minor sperrylite, moncheite, and platiniridium. Gold is a co-product, and concentrates comprise chromite, ilmenite, and magnetite. Beneficiation tests successfully concentrated precious metals from natural blacksand accumulations, but failed to concentrate low-grade lag gravels.

Jan 1, 2011

In the U.S. coal mining industry, a large cohort of miners is at or nearing retirement age. As these miners retire, there will be a need to hire and train thousands of new and most likely younger workers. Moreover, a large portion of safety trainers will also require replacement due to retirement. In a speech before the U.S. House of Representatives (2004), Bruce Watzman, Vice President for Safety, Health and Human Resources for the National Mining Association said, “[W]e will need to replace a major portion, approximately 50%, of the underground coal mining workforce within the next 5–7 years.” The large influx of new mine workers, along with the deficit in safety trainers, creates the challenge to provide consistent and effective safety training. Given the expected high turnover of the mining workforce, it is very likely that incoming workers will have much less experience than those leaving the workforce. Unfortunately, inexperienced miners have been shown to incur the highest rate of injuries. The piece of machinery most associated with these injuries is the roof bolting machine, which accounts for 56% of machinery-related injuries in underground coal mining. The National Institute for Occupational Safety and Health (NIOSH) has released a new report entitled “Roof Bolting Machine Operators Skills Training for a Walk-Thru Roof Bolter: Trainer’s Guide” (IC 9489). It is designed to help safety trainers develop struc-tured training for new operators of walk-thru bolting machines. This resource will help trainees learn, understand, and apply knowledge and skills. Included in the trainer’s guide are the following tools: [ ] a six-part DVD video series, a skills check survey, talking points, and a complete job training analysis. Also included is an exercise to help trainees learn more about their mine’s roof control plan, as well as a list of supplemental training and reading materials. On-site trainers can modify this guide to fit their particular mine conditions, machines and equipment, and work procedures. The goal of every coal mine safety professional is to increase safety awareness and make mines a safer place to work. The Walk-Thru Bolting Machine Trainer’s Guide will help teach new miners skills to create a safer working environment that will ultimately prevent or reduce on-the-job injuries. Safety trainers can also use the ideas and concepts from this guide to develop their own training skills for the safe operation of other pieces of underground coal mining equipment.

Jan 6, 2007

By J. V. Batty

In the course of the investigation of manganese mineral occurrences in the United States, Bureau of Mines examining engineers collected several lots of ore from the Black Rock, Kramer, and. Morgan-Cromar properties, Tooele and Juab Counties, Utah. Extensive laboratory tests were made to determine the amenability of the ores to standard ore-dressing methods of concentration. The Black Rock claims 1 and 2 are 42 miles northwest of Jericho, Tooele County, Utah. A. J. Huber of Salt Lake City and Ross Rydalch of Tooele, Utah, are the owners. The deposit-is reported to be a definite manganese fissure vein in quartzite along which considerable shearing and cross fracturing have occurred. Laboratory work was conducted on a 2-ton sample of run-of-mine ore procured by a Bureau of Mines examining engineer and two smaller, higher-grade samples submitted by the owners as a result of later development. The Kramer deposit is described as a bed of manganese oxides in quartz. The property is being worked by L. E. Kramer, Tooele, Utah, and is 41 miles northwest of Jericho) Tooele County, Utah, approximately 1 mile north of the Tooele-Juab County line. A 1-ton run-of-mine sample was submitted for testing by the examining engineer.

Jan 1, 1952

By John Nagy, Austin R. Cooper, Murray Jacobson

Data obtained in the Bureau's study of dust explosions of 313 elemental metals , alloys , catalysts , and ores comprising 54 types of material are summarized . Information is given on ignition temperature , spark energy for ignition , minimum explosion concentration , explosion pressure , rate of pressure rise , and in some instances , the admixed inert dust and oxygen concentration in an atmosphere required to prevent ignition of dust dispersions . The effects of particle diameter on explosibility and pyrophoricity are also discussed .

Jan 1, 1964

By Jack I. Paige

The Bureau of Mines conducted studies to provide data on the room temperature mechanical properties of Ti-6Al-4V alloy cast in waterglass-bonded zircon sand and to determine the effect of hot iso-static pressing (HIP) on these properties. Data on the cast and annealed Ti-6Al-4V alloy were compared with published data for forged and investment-cast Ti-6Al-4V alloy. The average Charpy V-notch impact strength compared favorably with the typical values of 17 ft?lbf for wrought material and 19.2 ft?lbf for investment-cast material. The room temperature mechanical proper-ties of cast and annealed material compared favorably with published values for investment-cast Ti-6Al-4V alloy and exceeded the specifications for (1) titanium and titanium alloy castings, grade C-5 according to ASTM B367-69, and (2) titanium alloy bars and forgings as specified in AMS4928H, except for the AMS4928H minimum requirement for reduction in area (25 pct). The minimum requirements are: tensile strength, 130 ksi; yield strength, 120 ksi (0.2 pct); and elongation, 6 pct. None of the specimens tested met the AMS4928H minimum requirement for reduction in area. The HIP process healed the internal casting porosity in the test specimens, but the fatigue strength was not significantly improved. The fatigue properties of both the cast and cast plus hot isostatically pressed castings were significantly lower than those of wrought products.

Jan 1, 1984

By Gerrit V. R. Goodman

Future coal mining systems will be able to cut from crosscut to crosscut where advances could exceed 100 ft. However, limitations arise when ventilating such mining systems. In deep advance mining, there would be no workers at the face to advance ventilation tubing or curtain manually. Traditional methods also provide no means for maintaining face ventilation after the miner backs away from the face. U.S. Bureau of Mines research is studying means to provide effective ventilation at cut depths beyond the current limit of 4D ft. Several innovative ventilation schemes are currently being considered. One such method is the use of a jet fan to ventilate a deep cut. A jet fan is simply a freestanding fan using little or no ducting to direct the ventilation flow. Jet fan testing in a 90-ft entry revealed that higher exit velocities and greater penetration depth occurred when various configurations were used to confine and direct the air flow. Additional testing also indicated that 2,200 cfm of fresh air was delivered to the face? 90 ft distant when a check curtain was used to limit entrainment around the fan. Without this curtain, this quantity dropped to only 1,000 cfm. This testing indicated that a jet fan was capable of providing ventilation to a distant face area. It also highlighted potential problems, such as recirculation at the fan and reentrainment in the jet flow. Despite these potential problems, jet fans may be adequate for ventilating cuts exceeding 4D ft.

Jan 1, 2010