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By H. A. Doerner

Tellurium is a silver white solid with metallic luster, the e17atal.line torm being ver., brittle aud e.g,s!ly powdered. It has a specific gravity of 6,27, melta at 45a0c. and boils at red het, giving off a. golden 1ellow vapor when air 11 excludei. When heated in air, telluri'UiD burns with a bl\te name tinged with green, and evolves wh1 te vapors ot tellurium dioxide. An amorphous form of tel­lurium, obtained by red.uction and precipi ta.tion from so).ution, haa II specific gr1.vity ot 6,015, and when heated ia cho.nged to the cry:.,talline variety. Telluri,a 11 insoluble in water, c&rbon diaiJ.phido, or h;rd.rochl oric acids, but it 11 41a-1olved bJ nitric or concen t1·ated. sulphi.U·ic acid. It 1..oea not tamiah in moiet ah•• 11 ree11tant to alkaline solutions, e,;:ctpt concentrated KOB, but it 11 cliaaolvecl by tuaed. &lkl 1••. I ts 11.to!!lic weight h..'l.a been the "J.Ubject ot mch controverq, bu\ t.he value 137 .5 :.a bl!ten generally accepted, Tho chflmietr:, of tellurium ia eim1lar to that ot IUlphur. It tonne throo xid.ee TeO, To02, and Te0 , al10 tellur14ea, t•llurite,, and. tellur1.t11, A number of halide compoWld.1, a 3iulph1de, and. a .ulpbat.e are known.

Aug 1, 1922

By Richard J. Mainiero

The Bureau of Mines has developed a prototype nonincendive explosive rock-breaker charge that can be fired unconfined in underground bituminous coal mines without the danger of igniting a flammable atmosphere that might be present. At present, unconfined shooting in underground coal mines is prohibited, but there are situations where the use of such shots would yield an overall improvement in safety. The charge consists of 1-1/2 lb of permissible water gel explosive in the form of a short cylinder 7 inches in diameter and 7/8 inches high, surrounded by a 1 1/2-inch-thick layer of damp salt, and encased in latex rubber reinforced with cheese cloth. The latex rubber housing provides a charge package that is strong enough to resist rough handling yet is pliable enough to conform to an irregular stone surface. A charge of this shape was found to be more effective at breaking rock than charges with lined or unlined cavities. Incendivity tests in a gallery have shown that the prototype charge will not ignite a flammable methane-air atmosphere when fired. Rock- breaking tests made with limestone boulders indicate that the charge will satisfactorily break stone slabs weighing 1 to 2 tons, and that two or more charges might be effective for slabs weighing up to 10 tons. In cooperation with the Mine Safety and Health Administration (MSHA), a test protocol for the certification of these charges as "permissible" for use in flammable atmospheres is being developed.

Jan 1, 1982

By R. L. Grant

"Carbon dioxide has been used for extinguishing electrical fires of many kinds (1, 3, 4) 3/ and more recently has been applied to some extent in fighting coal-mine fires (5). This report is concerned with the possibility of an electric current being conducted from a live power source, such as a trolley wire, across the impinging spray of carbon dioxide gas, to a metallic discharge nozzle, and then being grounded through the body of the person holding or touching the container. Rose and. Skinner (5) have described a case in which a fall of roof coal had brought down the trolley without creating a dead shot. The current was conducted in part through the loose coal to the rail, causing ignition of the coal. The fire was successfully extinguished with carbon dioxide.Dielectric data on pure carbon dioxide gas and liquid have been reported by Quinn and Jones (2). For the gas, the dielectric constants range from 1.00971 (35°C., 10 atmospheres) to 1.3072 (70°C., 151 atmospheres); for the liquid, 1.6016 (0°C., 50 atmospheres). Compared with the dielectric constant of air (1.0006, 1 atmosphere), these data, indicate that carbon dioxide in both gaseous and liquid forms is a very poor conductor of electricity, of the same order as air. 4/"

Aug 1, 1942

By Leonard Obert

This report describes an inexpensive triaxial equipment for testing 2-1 / 8- , 4- , and 5-5 / 8 - inch - diameter rock cylinders subjected to loading conditions comparable to those encountered in underground mining . Only minimal specimen preparation is required . The maximum axial load that can be applied is 250,000 lb , which corresponds to an axial stress of 70,000 psi for the 2-1 /8- inch- diameter specimen . The maximum radial pressure that can be applied is the same for each specimen diameter ; namely , 10,000 psi . The mechanical parts in this equipment are relatively easy to machine and fabricate . The cost of all parts , including the 250,000- lb hydraulic press but not including labor costs , was approximately $ 1,000 .

Jan 1, 1963

By Seth C. Schaefer

The Bureau of Mines has determined the standard Gibbs energies (AGf°) of CoS1.035 (cobalt sulfide) and Ni2.515S2 (nickel sulfide) with high-temperature galvanic cells using stabilized Zr02 (zirconia) as the electrolyte. Potential measurements were obtained for the cell Pt, CoS1.035, CoO, S02(g, 1 atm)//Zr02//02(g, 0.0114 atm), Pt, with the overall cell reaction C0S1.035(c) + 1.535 02(g, 0.0114 atm) = CoO(c) + 1.035 S02(g)¬ These results, combined with the best available data for ?Gf° of CoO and S02 from the literature, give the standard Gibbs energy of formation of CoS1.035 for the reaction Co(c) + 0 5175 S2(g) = CoS1.035(c) ?Gf° = -38.890 + 18.87 x 10-3T ± 0.185 kcal/mole (866.0 - 1,104.9 K), where temperature (T) is expressed in kelvins. Similar measurements were obtained for the cell Pt, N12.515S2, NiO, S02(g, 1 atm)//Zr02//02(g, 0.0122 atm), Pt, with the overall cell reaction Ni2.515S2(c) + 3.2575 02(g, 0.0122 atm) = 2.515 NiO(c) + 2 S02(g). Combination of these results with data for ?Gfo of NiO and S02 from the literature yields the standard Gibbs energy of formation of Ni2.515S2 for the reaction 2.515 Ni(c) + S2(g) = Ni2.S1SS2(c) ?Gf° -65.377 + 24.67 x 10-3T ± 0.541 kcal/mole (968.6 -1,053.7 K).

Jan 1, 1981

By Anthony T. Lannacchione, Donald G. Puglio

The Bureau of Mines developed data on the methane content of the Hartshorne coalbed, Haskell and Le Flore Counties, Okla. The methane content is calculated to be between 1.1 and 1.5 trillion cubic feet, based on an estimate of total coal in place of 2.4 to 3.2 billion short tons. Methane increases with depth, but the rate of increase decreases with greater depths. Degasification in advance of mining is recommended for all mines operating at depths greater than 500 feet to reduce hazards and methane explosions, decrease mine ventilation costs, and conserve the natural gas that would be otherwise wasted.

Jan 1, 1979

By R. L. Montgomery

Heats of solution of cerium metal and cerium (III) chloride in hydrochloric acid were measured. The standard heat of formation of the aqueous cerium (III) ion at 25° C is -166.1 ± 0.3 kcal/mole. Heats of solution of cerium (III) chloride in hydrochloric acid are consistent with the existence of a complex CeC1++ having a stability constant of 1 and a heat of complexing of 5.4 kcal/mole.

Jan 1, 1962

By A. R. Mumford

The fuel economy ot a. plant m be better than ite anxious friend.a J'ealize. A watchful a-aper1.ntend.ent of a Goverment plant, kn.owing that improvements in plant equipment bad. been made since hie atOkel'e were installed, was almosi per­ suaded to aubatitute a new t.,pe. The Bul'eau. of Mines was asked to aaoertain the a.cti.i&l performance ot the old stokera and tound. the plant alr doing from three to five per cent better than was promieed for the new egp.ipment. Tbe va.1.ue ot accurate knowledge of plant perfoimarice, am the need. ot eqm.pment to weigh and measure quantities is thus demonstrated. The boiler and ,tour ett1c1enc, was found to be 75 per cent, and the overall efficiency of the boiler, etoker• and economize, wae 78 per cent. Both records are high, and are to be attributed to ce in operation, to good working condition of the plant, and to the low rate ot evaporation, which was only aboui two-third., et the botler'e rated. capacity. The plant teated conaiated ot two la.boock & Wilcox boiler, tired b1 means of over teed 1toker1 and equipped wi t,b. a fuel economiaei- 1n the uptake. The bo1lel'a ,upplied ateam to two large water pump being used only intermittently.

Jul 1, 1922

By R. F. Abernethy

A chemical method of determining microgram quantities of arsenic in coal was investigated by the Bureau of Mines to supplement a semiquantitative spectrographic method of determining arsenic in coal ash. In accordance with a method recommended by the International Organization for Standardization, 1-gram samples of coal are decomposed by wet oxidation with boiling sulfuric acid (H2S04) and nitric acid (HN03) to remove the organic matter. After heating to fumes of SO3 to remove HN03, the arsenic is separated as arsine by the action of zinc in H2S04 solution. The arsine is absorbed in dilute iodine solution in which the arsenic is determined colorimetrically by the molybdenum-blue reaction. Two modifications of the method for obtaining the arsenic in solution, in addition to the wet oxidation method, give satisfactory results. The modifications are (1) furnace ashing with MgO added to the coal, followed by treatment with H2S04, and (2) extraction of arsenic from the coal by dilute HNO3 without ashing. Float-and sink-tests show that arsenic is associated mainly with mineral matter in the three coals examined. High-temperature ashing tests show that very little arsenic is volatilized from coal ash below 1,000° C, but it is virtually all removed from the ash at 1,300° C.

Jan 1, 1968

By John W. Buch

"INTRODUCTION The Ruhr coal basin is estimated to cover an area of more than 1,000 square miles. Here, the total thickness of the coal bearing formation (Carboniferous) is 10,500 feet, and drilling-hole have revealed 92 coal beds with a total thickness of 262 feet. 6/ Beds pitch from 0 to 90 degrees and about 70 percent of the wartime production came from beds that pitched less than 30 decrees. 5/For example at the Minisiter Stein mine, there are 24 minable coal beds ranging from 80 centimeters. (2 ft., 7 1/2 in.) to 250 centimeters (8 2 1/2 in.). The vertical thickness of the measures is 1,000 meters (3,200 ft.), and at this mine the deposits are covered with 150 meters (500 ft.) of surface wash. The cross section (fig, 1) at Fritz mine; Hoesch, A.G., Essen, Ruhr, is characteristic, The mines have been developed and worked to vertical depths of 2,000 to 2,500 feet by vertical shafts; main-level intervals are 500 to 700 feet apart. Haulage roads are straight, driven in rock, and centered as nearly as practical between property boundaries. Levels are sectionalized by driving crosscuts at right angles to the main haulage road on 800- to 900-foot centers. The roads are the main transportation arteries for the use of trolley or Diesel locomotives. A plan of the sixth main level (fig. 2) at the Bruchstrasse mine; Gelsenkirchener A.G., Bochum, illustrates main-level development and,sectionalizing with crosscuts. The cross section in figure 3 is that of the fourth crosscut west at the same mine."

Oct 1, 1946

By R. V. Ramani, C. B. Manula, A. Owili-Eger

That a close analogy exists between the flow of air in mines and the flow of current in electrical networks- has been known for a long time. The laws that have been used to solve series and parallel electrical circuits have been used to solve for the equivalent resistance in mine ventilation problems. Kirchhoff's current and voltage laws have also been adopted in solving mine ventilation network problems. It will be best to define a few terms here regarding networks, and with reference to Figure 1, these definitions can be elucidated. Figure 1 can be represented by the network in Figure 2 without losing any essential details. 1. A junction is a point where two or more airways meet. 2. The segment of a roadway connecting any two junctions is known as a branch. 3. A mesh is a closed path through the network. In the above network, B, C, D and F are the junctions, CF and CD are two of the branches and CFDC is a mesh. Kirchhoff's current law states that the sum of currents entering a junction. Applying this law to the junctions in the ventilation network, one obtains for junctions C and F, the following relationships: JUNCTION C: Q1 = Q4 + Q3 (1) JUNCTION F: Q2 + Q3 = Q5 (2) Similar relationships can be drawn for other junctions. Kirchhoff's voltage law states that in any complete electric circuit, the algebraic sum of the emf's must equal the algebraic sum of the voltage drops. In mine ventilation, the square law (Atkinson's

Jan 1, 1975

By C. B. Manula, R. L. Sanford, R. A. Rivell

A generalized flow diagram is presented in Figure 1, which shows the relationship of major model functions. This chart does not necessarily represent the anatomy of the computer program, but is designed to illustrate the informational interchange between major model functions. The related flow-charts-and computer program are listed in Parts I and II, Appendix A, respectively. Mine Car Stations The mine car stations are the activity centers for the model. The locomotive logic structure is designed to provide these stations with adequate cars and to clear them of car buildup. The model is designed to simulate a three stage haulage situation which suggests the need to differentiate station levels by type numbers. These are: a) TYPE 1 stations - mine cars are loaded here; b) TYPE 2 stations - intermediate stop and storage for mine cars; c) TYPE 3 stations - all mine cars that are stored here leave mine; and d) TYPE 4 stations - mine portal. TYPES 1, 2, and 3 have all loaded cars assigned to an ascending TYPE as their next destination. In input, if single stage haulage is designated, TYPES 1 and 3 do not exist, and if two stage haulage is called for, TYPES 2 and 3 are absent. A motor is not permitted to exchange cars between stations of the same type. Station Status Update. One major model function is to continuously evaluate the status of each mine car station. The major evaluations

Jan 1, 1974

By W. I. Nelson

This paper describing the mining practices at the Engels mine is one of a series being prepared by the United States Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The Engels Copper Mining Co. operates two mines about 3 miles apart in Plumas County. Calif. Both mines send ore to the same mill, and the methods of the larger, or Engels mine, are described in this paper. Between 800 and 1,000 tons of 1-3/4 to 2-1/2 per cent copper ore are mined daily from this mine by a shrinkage method. Connection is made with the Western Pacific Railroad at Paxton by the Indian Valley Railroad, which is 22 miles long and operates a daily mixed train to the mine.

Jan 1, 1930

By Geo S. Rice

"The most authoritative compilations on the coal resources of the British Isles are given in ""The Coal Resources of the World"" issued by the 12th International Geological Congress, 1913. The reserve, calculated to a depth of 6,000 feet, in seams containing not less than two feet of merchantable coal are as follows: Mining at present is conducted at depths from about 800 to 3500 feet. The shallower coals have largely been exhausted. The present average hoisting depth probably is about 1500 feet.The thickness of individual beds at present mined varies from about 2-1/2 feet up to 40 feet in thickness, the latter thickness being found in North Staffordshire. The coal is rarely found level, but is approximately level in some parts of Yorkshire. Anthracite is mined in limited quantities in Wales, and Wales also produces a very high grade semi-anthracite or smokeless coal, which is fa famous the world round, and is equaled only by the Pocahontas and New River coals in the United States:As concerns the methods of mining, these vary widely according to the pitch of the bed, the thickness of coal, and natural conditions, but the prevailing method is some form of longwall or semi-longwall, by which all the coal is extracted. The other principal method is a so-called pillar and, stall method, by which the coal is mined out, leaving square or rectangular pillars which are extracted on the retreat, making it virtually, a retreating longwall system. This method is applied where the roof is strong, and particularly in the thicker beds, as the longwall method is not so well adapted for mining where the thickness exceeds five or six feet, unless it is what is called a multiple seam, one in which there are partings of rock that provide material for building walls, which the roof in subsiding gradually squeezes down."

Jul 1, 1920

By C. A. Alien

The increasing activity in oil shale has had a tendency to direct the attention of the industry to any substance from which gasoline or other oils can be secured . Cannel coal for many years has been known, as a source of oil and formerly it was the only substance from which kerosene was obtained . The name of coal oil was given to kerosene because it was derived from cannel coal before any flowing wells were brought in in the United States . In an isolated region in Southern Utah there is an unusually thick and clean bed of cannel coal which laboratory experiments indicate can be made to yield about seventy gallons of oil to the ton . This coal was first described in Bulletin 341 of the United States Geological Survey under the title of Colob coal field . This field lies at the western and southern base of the Colcb plateau and extends from the town of Cedar City southward to Kanarra and then southeastward to the town of Mount Carmel . Cedar City is 35 miles south of east from Lund on the Los Angeles and Salt Lake Railroad which is the nearest railroad point . Mount Carmel is about 90 miles south of Marysvale , on the Denver and Rio Grande Railroad , which is the nearest railroad point from the eastern end of the field . The Colob coal occurs in Lower Cretaceous rocks and a number of wagon mines have been opened on the seam in the vicinity of Cedar City , Kanarra , and Mt. Carmel , but between these places the field has been very little prospected . The cannel coal , so far as known at present , is limited to a small area on the head waters of the north fork of the Virgin River in Township 39 and 40 South , Range 9 East . In this region it occurs as a bed 5-1 /2 feet thick over which lies a layer of bituminous coal 2 feet and 5 inches thick .

Feb 1, 1921

By E. D. Calvert

As part of its goal to minimize the requirements for critical and strategic minerals, the Bureau of Mines is conducting research to foster the use of domestically abundant materials such as molybdenum. This report describes the development of an investment shell molding technique that can be used to make castings of molybdenum and its alloys. The mold material is cubic Zr02 with a monoclinic Zr02 binder. The shell, formed by standard investment molding techniques described in the text, is prepared for molybdenum casting by firing for 6 hours at 1,550° C (2,822° F) or for 4 hours at 1,650° C (3,002° F). The resulting castings have predictable and reproducible dimensions with good detail. As-cast strength is poorer than the strength of wrought materials below 1,600° F. At and above this temperature, tensile strengths of cast and wrought materials are nearly equal. Aqueous corrosion of the castings in most media is insignificant.

Jan 1, 1982

By A. J. Barry

[This is the third report related to fundamental retail roof-bolting research in underground mines (1, 2)3/ and describes an investigation of the torque-load relationship for 3/ -inch, expansion-type mine roof bolts. In a previous investigation the relationship between torque and bolt load was established for 1-inch slotted-type bolts (1). The two types of bolts differ in diameter and method of tightening and consequently may exhibit different torque-load behavior. The 1-inch bolt is tightened by turning the nut, the 3/4-inch bolt by rotating the beaded bolt itself. Experience indicates that roof bolts should be tightened to moors satisfactory anchorage sand to minimise nag of tie roof over the mine opening. The generally accepted means for determining the bolt load is to see a torque wrench to measure he torque applied in tightening the bolt and, from a predetermined relationship between torque and molt load, to, determine the corresponding bolt load. Because frictional effects may vary between one type of shell assembly or bolt and others, 7 types of expansion shell units and 3 types of 3/4-inch-diameter, mild steel bolts were tested.]

Jan 1, 1954

By Susan M. Moore

According to the Mine Safety and Health Administration (MSHA) injury database, 227 knee injuries were reported in underground coal mining in 2007 [ 1]. Low-seam coal mines are those with extremely low working heights (<42?). Gallagher et. al [2] found that the average cost per knee injury in low-seam coal operations was $13,121.29. Thus, it can be estimated that the financial burden of knee injuries was nearly three million dollars in 2007. Pressure applied to the knee while kneeling and crawling is likely a risk factor. Typically, mine workers utilize kneepads to better distribute the pressures at the knee; however, their ability to reduce the stresses at the knee is unknown. The objective of this study was to determine the pressure applied to the knee during static postures used in low-seam mining while not wearing kneepads and while wearing two kneepads commonly used in the industry (one articulated and one non-articulated).

Jan 1, 2009

By Earl R. McMillan

"Coal washing commands the thoughtful attention of a steadily incre in number of people. Clean coal is not merely a luxury but is rapidly becoming a necessity in some industrial operations.Coal seams in the Northeast are rarely free from ""bone"" and shale or clay partings which vary from a fraction of an inch to several feet in thickness. Nearly all of the coal measures are folded and faulted, the coal seams dip at various angles, and in some cases are badly broken. In mining these seams fragments of the roof and floor, as well as partings of impur-ities within the seams, unavoidably become mixed with the coal, so that the raw coal as it comes to the surface often contains as much as 50 per cent, by weight of waste.At the Bureau of Mines experiment station at Seattle, the washing of this coal in order to improve it for commercial use has been studied. Since the process of coal-washing depends upon differences in specific gravity between the clean coal and, its associated impurities, the first problem undertaken was that of determining the specific gravity of the clean coal and of each parting of impurity contained in a large number of representative seams.It was found that the freshly-mined coal is practically saturated with water, this being observed in determining the effect of moisture content upon the specific gravity of the coal particles, selected from samples of coal varying from low-grade subbituminous up to semianthracite, all of which are found in the State of Washington. The specific gravity values determined for the cleanest particles varied from 1.28 to 1.35; in general, the higher the rank of the coal the hither the specific gravity."

Nov 1, 1920

By M. E. Tyrrell

Magnesia spinel (MgO.Al203) recovered from dusting slags in the system MgO.Al203-2Ca0.SiO2 is in the form of single crystals most of which will pass 35-mash. This investigation was undertaken by the Bureau of Mines to evaluate the concentrates as a refractory raw material. Three specific types of refractory bricks were studied: (1) dense, (2) lightweight bubble, and (3) insulating. Test specimens ware fabricated 1 by dry pressing, fired to 1,675° C., and tested by procedures common to the industry. The concentrates produced a refractor, having satisfactory density and mechanical strength; however, spinal is sensitive to thermal shock and the possibility of producing a spall-resistant brick using aggregate of such small grain-size must be considered remote. Lightweight refractorias fabricated of spinel bubbles were the most promising of the types tested. They were 30 percent lighter in sight than the dense refractory, their mechanical strength was good, and definite superiority in thermal shock resistance was indicated.

Jan 1, 1962