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By A. F. Jolly

As a part of ongoing research into the sulfidation partitioning of selected complex minerals, the U.S. Bureau of Mines conducted research designed to selectively recover Cu from sulfidized chalcopyrite (CuFeS2). Ferric chloride (FeCI3) solutions leached >90 pct of the Cu and <20 pct (sometimes < 10 pct) of the Fe in the sulfidized concentrates. Cupric chloride (CuCI2) leaches were even more selective, solubilizing essentially 100 pct of the Cu and < 5 pct of the Fe. In contrast, leaching non-sulfidized CuFeS2 with either FeCl3 or CuCl2 showed that somewhat more Fe than Cu dissolved. These studies demonstrate that Cu is substantially more leachable from sulfidized CuFeS2 than from nonsulfidized CuFeS2? The Cu-and Fe-bearing constituents generated as sulfidation products, CuS (covellite) and FeS2 (pyrite), respectively, are differentially dissolved. The solubility of Fe from pyrite in sulfidized CuFeS2 is much lower than the solubility of Fe from complex nonsulfidized sulfide where Fe and Cu are bound in the same crystal lattice. Thus, the Cu dissolves selectively, producing a high-Cu filtrate from which Cu can be recovered by cementation or by electrolysis. Flotation of CuS-FeS2 mixtures indicates partitioned phases can be physically separated if effective liberation can be achieved. Magnetic separation tests yielded less promising results.

Jan 1, 1991

Several federal and state agencies have promulgated regulations that require the installation of operator protective structures on mobile equipment used in mining, construction, agriculture and logging industries. These regulations cover many different types of vehicles, from small farm tractors to large rubber-tired front-end loaders, and require structures that help protect the operator from death or injury from vehicle overturns, from falling tree tops and logs, from falling rocks, and from tree limbs in clearing operations. Two general types of vehicle operator protective structures have evolved over the past twenty years. The first of these is the "Roll-Over Protective Structure&apos;&apos; or "ROPS" that is essentially a "roll bar" or "roll cage" that provides a relatively safe area for the vehicle operator if the vehicle should tip over and roll. The second protective structure is the "Falling Object Protective Structure" or "FOPS" that provides overhead protection against falling material. The terms "ROPS" and "FOPS" are often used interchangeably (sometimes inaccurately) with "cabs", “canopies” , "roll bars" , protective structures" and other such descriptive names. In this report, "ROPS" describes the function of the structure; "FOPS" also describes a particular function. Thus a ROPS/FOPS could describe a cab or a canopy that provides both roll-over protection and falling object protection. “MESA” is used as an abbreviation for the Mining Enforcement and Safety Administration; "USBM" is used to abbreviate the U, S. Bureau of Mines.

This report describes magnetic field measurements in the Helvetia Coal Co. Lucene #8 Mine for purposes of deriving a mapping of the magnetic field strength covering the major haulageways which contain conductors. The measurements were performed by Terry S. Cory, P.E. under U.S. Bureau of Mines purchase order P0372716. Assisting in performance of the measurements were personnel from the Bureau of Mines, PMSRC, and Helvetia Coal Co. Acknowledgement is given to Engineer Tom Strong of Helvetia Coal Co. who accompanied the measurement team and who lended support in performing the measurements and in supplying valuable engineering information for use in evaluation of the results. The results of the testing at medium frequency show that coverage of the entire mine area containing conductors can be achieved employing wireless radio techniques whereby radio signals are coupled into and are carried by these conductors. These results confirm earlier qualitative testing of the Collins Mine Wireless Radios in this mine. These results, performed over the frequency range 71-2890 KHz, illustrate the effect of frequency on the radio propagation with the conclusion that the best overall coverage is obtained at frequencies approximating 1000 KHz. This report presents all the raw data and the reduced data in the form of magnetic field strength contour maps. Sufficient information is provided to enable independent reduction of the data. A summary of observations which can be made directly from the contour maps is given.

Jan 9, 1977

Improve the reliability and accuracy of subsurface images using constrained tomography with enhanced ray-tracing capabilities. Background Geophysical tomography is a technique for imaging the structure of a rock mass using seismic or radio waves, in the same way that medical CAT scans image human tissue using X-rays. Tomography has found numerous practical applications related to mining, including lithologic and structural characterization, fracture detection and fluid monitoring, void detection, and evaluation of stress state and integrity of mine structures. Problems Two fundamental problems have largely prevented geophysical tomography from enjoying the tremendous success achieved by medical tomography. The first is a consequence of practical limitations on the placement of sources and receivers of wave energy: ideal resolution can be attained only when the region being imaged is entirely surrounded by sources and receivers, so that it is crossed by rays traveling in all possible directions. When such coverage is impossible or impractical, the inversion becomes underdetermined: there id not enough information in the measured data to provide a mathematically unique solution. The second major problem in geophysical tomography is the necessity for detailed ray tracing. Commercial software, as well as previous U.S. Bureau of Mines (USBM) software, employs a ray-shooting algorithm that may be unable to model some ray paths when velocity contrasts are larger than about 100%. These ?shadow zones" result in loss of data and degradation of reconstructed images.

Jan 1, 1994

Improve underground mine roof bolt support systems by alleviating problems associated with certain ground support systems currently being used. Approach Convert a passive resin-grouted roof bolt system into a uniform, tensionable roof bolting system. Background Resin-grouted roof bolts are one of the most common forms of ground support in U.S. underground coal mines. These support systems can be installed with a full-column of grout and be loaded with subsequent roof movements after installation. This is called a "passive" support system. An alternative to the passive support system is the mechanically-anchored, tensioned roof bolt system. This system is installed with resin grout. This system is designed to load or tension the support during installation by using a mechanical anchor, coupling, or threaded nut after the resin has properly cured. It is called an "active" support system and is used extensively for improved strata control in a laminated geologic deposition or in difficult ground conditions. To ensure that active bolts have been properly installed, the bolt loads must be checked by using a torque wrench or other suitable equipment. Unfortunately, this practice presents potential safety hazards and has limited accuracy. Laboratory and field experiments also reveal that the torque-to-tension ratio developed on active support systems can vary by 50% from bolt-to-bolt. Variations in bolt load installations can induce stress concentrations and lead to roof degradation or failure.

Jan 1, 1991

By BUREAU OF MINES

The cheapest method of handling gravel in placer mining operations is by hydraulic mining . In working gravel deposits by hydraulic mining , it is essential that an abundant supply of water under sufficient head can be economically developed and that there is sufficient grade for sluice boxes and for disposal of the tailing . Without dumping facilities , simple hydraulic mining is an impossibility . The cost of hydraulic mining may range from 2 cents a yard under favorable condıtions to 12 or even 20 cents under less favorable conditions and to 35 cents or more a yard in Alaska , according to conditions of operation , and if frozen gravel is encountered . When it is necessary to elevate gravel , the costs may exceed 60 cents a cubic yard . When the natural conditions do not permit of hydraulic pining proper , other methods of elevating the grade are employed , some of which are described below . Bucket dredging has replaced hydraulic mining in importance in California and other states where hydraulic mining was once extensively carried on , and is by far the cheapest method of elevating gravel when mechanical methods are required and the physical conditions are suitable for dredging . Dredging costs vary greatly under the different conditions encountered , and the total amount of gold to be recovered must of course be enough to warrant the cost of a dredge installation . Gold dredging operations in the United States are fully described in Bull . 127 , U.S. Bureau of Mines .

Jan 1, 1922

By Wm .. W. Odell

There is outlined below the essential facts brought out in an investigation into the causes for emulsion difficulties as experienced at many water gas plants . The investigation was conducted under a cooperative agreement between the University of Illinois Engineering Experiment Station , the Illinois State Geological Survey , and the U. S. Bureau of Mines . Funds of the Illinois Gas Association were used to defray a part of the costs . Active assistance was rendered by the Peoples Gas Light and Coke Company , of Chicago , who furnished a laboratory at Chicago for conducting the experiments , and loaned the services of Mr. E. A. Thiele to help with the laboratory work . A full report on the results of this work will be published by the Bureau of Mines later but it is believed desirable to bring the principal results now to the attention of the industry . In almost every gas plant where carbureted water gas is made , some difficulty is experienced , at one time or another , in separating the tar fran the water that condenses from the gas . The fact that annoyance from this source is ever present in some plants , and seldom present in others , leads to the belief that certain operating variables have considerable to do with the formation of difficulty separable tarwater emulsions . Accordingly , when samples of tar were collected for laboratory study , the operating conditions and methods were simultaneously observed and recorded.

Mar 1, 1922

By Lloyd A. Morley, Robert Stefanko

In the context of the following report, an hazardous location can be described as any industrial area in/which flammable or explosive gases, vapors, and dusts can be encountered. When electrical apparatus is used in such hazardous atmospheres, the chance of a dust or gas ignition is ever present. Consequently, in an effort to reduce the ignition hazard, several protection systems have been devised. Such systems are termed electrical hazard reduction techniques. The most widely accepted and used of these, the explosion-proof enclosure, is the principal subject of this report. However, other techniques are briefly mentioned. Hazard reduction techniques used in coal mine atmospheres (which can contain methane, coal dust, and air mixtures) are classified as Group I. The explosion-proof enclosure commonly used in mines is defined by the USBM Schedule 2G as a device that can contain internal explosions of methane-air mixtures without undergoing damage or excessive distortion and without an ignition of a surrounding methane-air mixture or discharge of flame. (100) Internationally, the definition remains the same except the words "discharge of flame" are not present. (4,5,31,42,52,76,102) The latter description often refers to flame-roof enclosure construction, but the terms "flameproof: and "explosion-proof" commonly have the same connotation. These enclosures which may not be vapor tight, are distinguished by heavy-wall cast or welded construction and bolted or threaded close fitting flanges. Explosion-proof enclosure techniques have been utilized in U.S.

Jan 1, 1974

By V. P. Bhavanandan

The mucus secreted in the respiratory tract provides the first barrier against inhaled particulate and gaseous toxicants. Trachea removed from pathogen-free rats were maintained as organ cultures and used to study the effects of coal dust exposure on the synthesis of mucin. The high molecular weight isotopically labeled (3H-glucosamine, 14Cleucine or 35S-sulfate) mucin could be purified by gel filtration, treatment with testicular hyaluronidase, ion exchange chromatography, delipidation and CsBr density gradient centrifugation. To examine effect of coal dust on mucin production, groups of explant cultures were exposed to media containing coal dust at 100 µg per ml every 2 days for 2 weeks while control cultures were treated with media without dust. Analysis of the spent culture media showed that treatment with dust markedly decreased the production of nondialysable glycoproteins as well as hyaluronidase-resistant acid-precipitable fraction consisting mainly of mucin. Since the synthesis of protein was not affected to the same extent the decrease in mucin production is not entirely due to cell death. In separate experiments rats were subjected to in vivo coal dust exposure in inhalation chambers and tracheae of these and control rats were removed for explant cultures. The incorporation of precursor isotopes into mucin by these explant cultures are being examined. (Supported by U.S. Bureau of Mines through the Generic Mineral Technology Center for Respirable Dust under grant G1135142, project 4210).

Jan 1, 1988

By M. B. Cooke, A. D. Bauer, E. W. Dean

The Bureau of Mines is collecting and analyzing representative samples of crude petroleum from all the producing fields in the United States , and the results are being published in a series of reports that are preliminary to the issue of a bulletin covering the entire survey . The bureau has recently completed a survey of crude oils from the Kansas district . In all 27 samples were collected and analyzed , under the direction of A. W. Ambrose , chief petroleum technologist of the Bureau. Valuable assistance was received through the cooperation of oil companies operating in the State , especially the Prairie Pipe Line Co. , and the Empire Pipe Line Co. The present report issued as Serial 2322 , on the Kansas crudes , forms the fifth of the series . Of the four previous papers , the first ( No. 2202 ) deals with crudes from the Eastern fields of the United States , the second ( No. 2235 ) with crudes from the Rocky Mountain district , the third ( No. 2290) gives additional data , cn viscosities and pour tests , for the crudes from these two fields , and the fourth ( No. 2293 ) covers the fields of northern Texas , northern Louisiana , and Arkansas . The details of the methods of collecting samples , making laboratory tests and interpreting results , have been discussed in these earlier reports . It has also been pointed out that the only adequate method of interpreting analyses of crude oils is to compare the individual reports with the analysis of some crude oil that is familiar to the operator . For this reason , no comprehensive discussion of the results of the Kansas survey is attempted, although some general statements may be made .

Feb 1, 1922

By John D. Bardill

This report covers the magnetic survey in the Redford-Clayburg area , which was part of a general survey of magnetite deposits in New York started in 1943 . Other areas being surveyed include the Star Lake district , St. Lawrence County; Russia Station district , Clinton County; Brewster district , Putnam County; and the Sterling district , Orange County. Only a relatively small portion of the area was covered by reconnaissance and detailed surveys . Results were promising enough to warrant additional work. Magnetic surveys of this type serve as a basis for selecting areas for diamond drilling by the Bureau of lines .

Jan 1, 1947

By Oliver Bowles

"On January 15, 1920, a man was killed by falling rock in a limestone quarry in Utah. The quarry was visited by a representative of the Industrial Commission of Utah, and the cause of the accident was carefully determined. The facts concerning this accident, and the Bureau's recommendations are given in some detail in the hope that quarrymen may take steps to avoid dangerous conditions, and thus reduce the liability to accident.The quarry rock face is about 180 feet high, and the ledge is covered with an overburden of 10 to 20 feet of a mixture of soil and boulder. The rock face is not vertical, but slants at an angle of about 45° to 50°, while the stripping face stands at an angle of 70° to 80°, and is flush with the rock face. The conditions are shown in the accompanying figure.The man who was killed was employed in breaking rock at the foot of the quarry wall. The sun had been shining on the stripping face, and probably thawed the ground, thus permitting a boulder weighing about 20 pounds to roll down the slanting face, striking, and almost instantly killing the workman who was working with his back toward the quarry wall."

Feb 1, 1920

By Thomas V. Falkie, R. Venkataramani

The method of analysis was to test a large model containing potentially significant variables and on the basis of the results obtained, to reduce the model to one containing only the essential significant variables. This stepwise procedure of "scanning" a large proposed model and subsequently condensing the model consisted of two cycles of the same series of computational procedures. Data Preparation A majority of the variables measured were continuous over a specific range of values; for example, the variable "Width Ratio" varied in practice from 0.25 to 1.00. However, "dummy" values were assigned to certain operational variables in order that these varia¬bles would have numerical expression. The following variables were described in this manner. Variable "Dummy" Value x3: Development/Pillaring 0, if pillar extraction was being done 1, if development mining was being done x4: Boxcut/Open Cut 0, if a box cut was being made 1, if an open cut was being made The variables under consideration are represented symbolically as follows: Y: Loading rate (tons per minuts): TONS/MIN x1: Ratio, width of cut/width of cutter: WDRATIO x2: Ratio, height of cut/diameter of cutter: HTRATIO x3: Development or pillaring: D/P

Jan 1, 1972

By Raymond B. Ladoo

Cne of t·: . .:: i::,portt recent developrr.ents in the feldspar industcy l:.a.s beer. tl:.e r,:ipid. rise of Ne·N H.v-:psr.ire as a. feldspar producing State. Tl:.e unusual size and purity of t: e deposit now 'being worked ne3.r Keene, and tr.a i.nproved metl:.ods ot:' rr.ining srd ir,illing used l:.ave been responsible foe tt.is situation. ti'eldsp'.:l. w'ls occ':tsiona.lly produced sorr.e ye1rs ago in srr.a.ll (tuantities in New Hrunpshi :e, but t::.e State had not been considered a producer of" feldspar ui til lS3l. In the s::ring of tr .. at yea!', t:.e '[eane iic Products co. of Keene, N.H., beg3Il in a srr.9.ll way tl:e production of feldspar fro:n t1eir property in Gilsum, H.H., whicr. l-.a.d long been opera.tei a.s a :tl.ca mine. The purity of the feldspar at enoe '\ttracted f''.lvorai)le attention. and tt.e production of crude ore rapidly in­ cre'.\sed. Early in 1922, a new company, t'he Golding-Keene Co,

Sep 1, 1922

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

D. 1 Most Effective Salts A. Ammonium Phosphates Monammomium phosphate and diammonium phosphate (salts of ortho phosphoric acid) are superior to the triammonium salt in fire-resisting properties. Of these two, the monammomium salt is chemically the more stable. It is also held very retentively by a number of woods, thus reducing leaching out of the salt if exposed to water. Saturated aqueous solutions of mon- or di-ammonium phosphates have vapor preservatives corresponding to an atmospheric relative humidity of 9Z to 93 percent, the wood, will, therefore, not attract any moisture at humidities below this figure. Low concentrations (1 lb dry fire-retardant per cubic foot of the dry, treated timber) will stop flame and high concentration (5 lbs. per cubic foot) will prevent smoldering. B. Ammonium Sulphate In low concentrations ammonium sulphate has only a small effect on flame propagation, but its effect is marked when concentrations of the order of 20 percent are employed. It has no appreciable effect on smoldering. It is more corrosive to metals than are the phosphates, but is less corrosive than ammonium chloride or magnesium chloride. It is possible to leach it out of wood by prolonged and continuous action of water The vapor pressure of the saturated solution corresponds to 81 percent atmospheric humidity.

Jan 1, 1976

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

D.2 Principal Types of Coating A Sodium Silicate Sodium silicate is a good fire retarder when freshly applied, but it loses its effectiveness if the relative humidity is at all high, thus exposure to a relative humidity exceeding 65 percent causes a serious decrease in the effectiveness after only one month. In fire, sodium silicate swells to a frothy mass (intumescence) which hardens and insulates the wood against heat. This property is destroyed by exposure to moisture. Manufacturers of many of the proprietary paints containing silicates state that their products have overcome this difficulty The reagent may be applied alone, or, better, in a mixture with lime-water and common salt, or with inert fillers such as kaolin or asbestos. B Ammonium Phosphate Strong solutions (25 to 35 percent) of monammonium phosphate or diammonium phosphate give good protection. Two or three coats of hot solution should be applied either with a large flat brush or an ordinary paint spray gun The solution should be applied as hot as possible, as this improved penetration, and it should be the aim of the operator to apply 4 lbs of reagent, i e , one gallon of 33 percent solution to every 100 square feet of surface

Jan 1, 1976

By Richard A. Thomas, Isaac A. Zlochower, Gregory M. Green, Kenneth L. Cashdollar, Martin Hertzberg

This paper reports the results of flammability studies for methane, propane. hydrogen, and deuterium gases in air conducted by the Pittsburgh Research Laboratory. Knowledge of the explosion hazards of these gases is important to the coal mining industry and to other industries that produce or use flammable gases. The experimental research was conducted in 20 L and 120 L closed explosion chambers under both quiescent and turbulent conditions, using both electric spark and pyrotechnic ignition sources. The data reported here generally confirm the data of previous investigators, but they are more comprehensive than those reported previously. The results illustrate the complications associated with buoyancy, turbulence, selective diffusion, and ignitor strength versus chamber size. Although the lower flammable limits (LFLs) are well defined for methane (CH,) and Propane (CA), the LFLs for hydrogen (HZ) and its heavier isotope deuterium (D2) are much more dependent on the limit criterion chosen. A similar behavior is observed for the upper flammable limit of propane. The data presented include lower and upper flammable limits, maximum pressures, and maximum rates of pressure rise. The rates of pressure rise, even when normalized by the cube root of the chamber volume (V 1/3), are shown to be sensitive to chamber size.

By John J. Mulligan

Lead-silver deposits in the Omilak area, on the western slopes of the Darby Mountains, Seward Peninsula, Alaska, were investigated by the Bureau of Mines, during the 1953 and 1954 field seasons, as a part of the U.S. Department of Interior&apos;s continuing program for the development of Alaska&apos;s resources. The Omilak area was the scene of early day prospecting and mining activity. The Omilak mine, which operated from 1881 to 1890, was the second producing lode mine in Alaska; the first was a small gold mine near Sitka. Several hundred tons of ore were produced at the Omilak mina; as an indication of grade, 41 tons shipped from Omilak in 1889 contained 75 percent lead and 142 ounces of silver per ton. A prominent, nearby occurrence of lead-silver minerals, found but not explored during this period, has since become known as the Foster prospect. Subsequent exploration of this prospect revealed an abundance of massive galena occurring on an outcrop and as float scattered through limestone talus. Evidence of lead deposition, together with the generally high silver content of lead ores previously shipped from the district, indicated that deposits might be found which would be commercially valuable even in this remote area. To investigate the possibility, the Bureau of Mines made a reconnaissance of the Omilak area and did bulldozer trenching, diamond core drilling, and sampling at the roster prospect. Data resulting from the investigation are presented in detail in this report and are summarized in the following paragraphs.

Jan 1, 1962

By Gerrit V. R. Goodman, Charles D. Taylor, Edward D. Thimons

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 40 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 40 ft.

Jan 1, 1992

By R. V. Ramani, R. Bhaskar

"One of the primary means of control of health hazards from respirable contaminants in mine atmospheres is through design and operation of mines to meet mine health and safety regulations and recommended practices. A U.S. National Academy of Sciences study concluded that for significant progress in coal mine dust control, research should be directed more toward obtaining fundamental understanding of the origin, transport and characteristics of respirable coal mine dust. Theoretical and experimental studies on transport of dust · in mine airways, particularly coordinated efforts to validate theory with practice, are scarce. Some empirical models, developed on the basis of experimental data, are available but these models cannot be applied to new conditions. The purpose of this paper is to present the results of theoretical and experimental studies on the transport and deposition of dust in mine airways. This study is a part of an ongoing research project in the Generic Mineral Technology Center on Respirable Dust.In the paper, the assumptions of the modeling phase of the project and the development of a convectiondiffusion equation for dust transport in mine airways are outlined. The important aspect of the modeling effort is the capture of the deposition phenomenon. The experiments performed under controlled conditions in a typical mine airway, as well as under normal mine operating conditions, are discussed. The comparison of the model predictions with experimental results are made to identify critical areas of agreements and deviations. The implications of the findings and areas for further research and development are presented."

Jan 1, 1990