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Analyze variably saturated flow in mining and other environmentally sensitive settings through the use of personal computer (PC) based software. The Problem There is an increasing need for mining companies to quantify water contaminants and their migration in the unsaturated zone. New and innovative computer models are therefore necessary to more accurately assess the potential impact of mining activities on groundwater resources and the environment. Applications for unsaturated flow modeling include (1) assessment of the impact of surface or underground extraction mining on flow conditions; (2) assessment of various hydrologic designs for resource recovery, such as in heap leaching or in situ leach mining; (3) assessment of the transport of conservative nonrcactive constituents in response to migration from spoil piles, or acid mine drainage; and (4) assessment of any combination of the above to facilitate expeditious permitting for mining operations. Since the mid 1970's there has been a proliferation of mathematical models and procedures for solving unsaturated now problems; however, few of these approaches have been integrated into software for public use. Commercially available unsaturated flow software models typically are limited to a single application and have restricted approaches. For example, computer codes that solve the unsaturated flow problem based on an analytic expression arc restricted to a simple geometric shape, homogeneous and isotropic materials, and provide only information regarding pressure and flow conditions in specified wells. The variably saturated computer codes that take advantage of the finite difference or finite element approach arc often restricted to either steady state or transient solutions; utilize one specific moisture-retention relationship and moisture-dependent permeability function; do not account for hysteresis; and are used with specific hardware such as a mainframe or work station. This restricts their use because they arc hard to interface, and arc often poorly documented, support dependent, and expensive. The mining community needs a flexible, more broadly based, variably saturated fluid flow simulator for the PC-platform to more accurately predict fluid movement in the mining environment.

Jan 1, 1991

By John M. Devine

The oxygen bomb-is used extensively for determining sulphur in petroleum, although it has been suspected that the results obtained with this method are somewhat lower than the true varies. In this paper are compared the results given by the oxygen-bomb and Carius methods, the latter being generally accepted as the standard procedure for the determination of sulphur in organic compounds. The Carius determinations given hero were made in connection with a special study of this method.4 Only petroleum oils of the less-volatile type are covered in the present work. Summary and Conclusions. When used with oils containing 2.3 to 0.15 per cent of sulphur the oxygen-bomb method gives results that are consistenly if slightly lower than those obtained with the Carius method. This variation, for the oils used, amounts to 3.1 per cent (on tae basis of sulphur present) for the sample containing 2.47 per cent of sulphur, and gradually increases (as the percentage of sulphur in the oils decreases) to 7.3 per cent for the oil containing 0.15 per cent of sulphur. With the oils studied the presence of ammonium nitrate in the bomb does not influence the results materially.

Jan 1, 1928

By T. G. Carnahan

The Bureau of Mines conducted research to simulate in situ leaching of a porphyry copper sulfide ore. The purpose was to determine the effects on copper leaching of additions of NaCI to a conventional sulfate leach system and to analyze the oxidant requirements and the oxidation products that resulted from leaching of the sulfide minerals in the ore. Baseline sulfate and sulfate plus 2-pct-NaCl-leach-solution experiments employing 167-kg (367-lb) and 152-kg (333-lb) charges, respectively, were conducted. The minus 25.4-cm (10-inch) ore was leached at 90° C under flooded conditions with 2.8 MPa (400 psig) of oxygen bubbling through the system. Sixty-seven pct of the copper was extracted in 1,236 days of leaching in the NaCI experiment, whereas 47 pct of the copper was extracted in 913 days of leaching in the baseline experiment. Diffusion into and out of the ore fragments controlled the rate of leaching, which precluded enhancement of the leach rate by the chloride ions. The calculated oxygen consumption was 3.17 kg/kg of copper extracted in the baseline experiment and 3.46 kg/kg of copper extracted in the experiment to determine the effect of chloride ions.

Jan 1, 1982

By Jami M. Girard

INTRODUCTION Slope stability accidents are one of the leading causes of fatalities at U.S. surface mining operations. The Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) is currently conducting research to reduce the fatalities associated with slope failures and other unexpected failures of ground. The purpose of this paper is to introduce various warning signs of slope instability so operators are better able to recognize hazards. The most common slope monitoring equipment and practical methods of installation are discussed as well as the limitations of these systems. CONSEQUENCES OF SLOPE FAILURES Unexpected movement of ground causes the potential to endanger lives, demolish equipment, or destroy property. Between 1995 and 2001 (2nd quarter), 34 fatalities were caused by ground instability. This accounts for approximately 15% of all surface mine fatalities (Figure 1). These figures include fatalities classified by the Mine Safety and Health Administration (MSHA) as “fall of face or highwall,” “powered haulage,” “equipment,” and other MSHA accident categories, where the primary cause of the accident was unanticipated movement of the ground. This includes fatalities resulting from bench and highwall failures, rock falls, waste dump and stockpile failures, and the collapse of unknown underground workings. [ ]

By Gregory M. Molinda

The Bureau of Mines conducted an investigation into the occurrence of outbursts of salt known to be responsible for explosions, fatalities, and damage in domal salt mines. The purpose of the investigation was to develop a basis for predicting these outbursts based on geologic and associated physical properties of salt. The investigation was conducted at the Cote Blanche salt mine in southern Louisiana. Because outbursts are the primary mode of methane emission into the mine, more than 80 outbursts, ranging in size from 1 to 50 ft in diameter have been mapped. These outbursts generally are aligned and elongate parallel to the direction of salt layering. More than 200 salt samples, both random and selected, were tested for methane content. It was found that outburst zones are well correlated with high methane content. Detailed mapping also revealed that the zones are well defined, with salt crystal size abruptly increasing upon entry into the zone. The intensity of folding and kinking of the salt layering within the outburst zone also appears to increase. An interbedded sand layer occurring throughout the mine does not appear to be a significant source of methane. However, fine-grained salt may be related to outburst occurrence.

Jan 1, 1988

By N. W. Lord

This volume contains the descriptions of the samples whose analy- ses are published in the preceding volume, Part I of this bulletin. The descriptions have been compiled from the notebooks of the per- sons who collected the samples, have been condensed from accounts given in published reports of the United States Geological Survey, or have been furnished by the collectors themselves. Inasmuch as the descriptions represent the work of many persons during a period of six years, and inasmuch as they were recorded under widely differing conditions, they necessarily vary in fullness of detail. The descriptions are published for two purposes: (1) To prosent such information regarding the character of the coal, the impurities in the beds sampled, and the nature of the roof and the floor of the beds as has a definite bearing on the significance of the analyses of the samples, and (2) to give any supplementary details such as the capacity or the output of a mine, the method of mining and prepar- ing the coal, and the chief uses to which it is put, that may be of assistance to Government engineers or purchasing agents, and to other persons, in preparing specifications and awarding contracts for fuel.

Jan 1, 1913

By Burke Cartwright, S. F. Ravitz, Lloyd R. Michaels

This method is similar to the reduction of dolomite by ferrosilicon, in that it does not require the direct use of electrical energy; like ferrosilicon, the calcium carbide must be produced in an electric furnace, so that the reducing agent in both processes may be considered in some respects as “stored” electrical energy. The reduction of magnesium chloride by calcium carbide is exothermic, takes place rapidly at ordinary pressure and at relatively low temperatures, and can be carried out in ordinary steel equipment, whereas the reduction of dolomite by ferrosilicon and the carbothermic reduction of magnesium oxide are endothermic, require high temperatures, and present serious problems with respect to materials of construction. Because of its apparent simplicity and other advantages, the Bureau of Mines has briefly investigated the reduction of magnesium chloride by calcium carbide. Published data on the reduction of magnesium chloride by calcium carbide are meager. Matignon states that reduction is fairly rapid at 1,200º C. Matsuura claims that magnesium chloride is not reduced by calcium carbide at atmospheric pressure and 800º C; however, by keeping the pressure under 10 mm. of mercury he was able to obtain small globules of magnesium at 800º C.

Mar 1, 1947

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 Andrew B. Cecala, Robert J. Timko, Alexander D. Prokop

Bag loading and stacking processes are the highest dust-exposure job categories in the metal/nonmetal mining industry.1 To cost-effectively decrease respirable dust levels, the Pittsburgh Research Center of the National Institute of Occupational Safety and Health (NIOSH), formerly of the U. S. Bureau of Mines, designed and tested a system called the Bag and Belt Cleaner Device (B&BCD). [ ]

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 Seth C. Schaefer

The Bureau of Mines studied the standard free energies2 of formation of ferrous fluoride (FeF2) and ferric fluoride (FeF3) with high-temperature galvanic cells employing calcium fluoride doped with 1 mole-pet yttrium fluoride as the electrolyte. A free-energy change for the cell reaction Fe (s) + NiF2 (S) = FeF2 (S) + Ni (s) together with the standard free energy of formation of nickel fluoride yields a standard free energy of formation of ferrous fluoride from the elements of ?GF° = -168.74 + 30.63 x 10-3T ± 0.41 kcal/mole (897-1,098 K). (2) Combining the standard free energies of formation of magnesium fluoride, ferric oxide, and magnesium oxide with the free-energy change for the overall cell reaction 3MgO(s) + 2FeF3 (s) = 3MgF2 (S) + Fe2 03 (S) (3) gives a standard free energy of formation of ferric fluoride from the elements as ?Gf° = -281.45 + 90.46 X 10-3T ± 0,67 kcal/mole (880-935 K). (4) Free energies and equilibrium fluorine pressures for the two univariant equilibria of the Fe-F system are tabulated and illustrated.

Jan 1, 1975

By R. V. Ramani, P. M. T. White, D. Sutton

5.1 Incorporation with the Master Design Simulator Figure 1 diagrammatically illustrates the interaction between the various sub-systems that go to make up the total Master Design Simulator. As a total system, all sub-systems will be scheduled as needed by the controlling program. The data require¬ments for each will be made available either by providing common storage in core or by outputting data to external storage devices such as magnetic tape, disk, drum, etc. The incorporation of the Geology and Reserves sub-system into the total system involves the establishment of an interface through which data may be readily dissemminated in either direction. This interface will be provided by a geological data library in which all information available from the sub-system is stored and can be readily accessed by the main program and/or other sub-systems. In Figure 7, the information flow between the Geology and Reserves sub¬system and other sub-systems is shown. 5.2 Independent Function Geology and Reserves sub-system is capable of functioning as an independent unit or in direct communication with another sub¬system. This is possible by either continued use of the data library or by redirecting output to other peripheral devices separate from the total system libraries. (Figure 8).

Jan 1, 1974

By Alexander May

In this Bureau of Mines publication stability constants for complexes of diethylenetriamine, 2-aminoethyl sulfide, triethylenetetramine, and 1,8-diamino-3,6-dithiaoctane with copper, nickel, zinc, and cadmium were deter-mined. The amine complexes were found to be much more stable than the analogous thio complexes. The results are interpreted in terms of possible molecular structure of the complexes.

Jan 1, 1974

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

THIS PROGRAM TRANSFORMS FREE FORHATED BRANCH DATA INTO A FORMAT SUITABLE FOR INPUT TO THE PENNSYLVANIA STATE UNIVERSITY MINE VENTILATION SIMULATOR (PSU/HVS 1. BRANCH RESISTANCES ARE ASSUMED TO HAVE BEEN ALREADY CALCULATED, IIOWEVER THIS PROGRAM CAN BE EASILY MODIFIED TO HANDLE THE ADDITIONAL INPUT DATA REQUIRED FOR RESISTANCE CALCULATIONS IN THE PSU/MVSO THE PROGRAM IS WRITTEN IN FORTRAN IV WITH WATFIV.

Jan 1, 1977

By Robert B. Schluter

The Bureau of Mines investigated separating copper-nickel mattes to recover a copper-rich fraction suitable for processing by conventional copper metallurgical processes and a nickel-rich fraction suitable for processing in a hydrometallurgical nickel circuit. Distribution of cobalt and precious metals between the copper and nickel fractions was also determined. A matte containing a nominal 65 pct Cu, 9 pct Ni, 4 pct Fe, and 20 pct S was separated into a copper fraction that comprised 80 pct of the matte weight and contained 70 pct Cu and <1.5 pct Ni, plus a nickel fraction that contained 40 pct Ni and 30 pct Cu. Recoveries of copper and nickel into their respective fractions were 90 pct and 87 pct. These results were obtained in a laboratory flotation cell at a matte grind of 90 pct minus 500 mesh and a pH of 12.4, using 1.7 pounds DPG (diphenylguanidine) per ton of matte as collector and frother. Magnetic separation was used to remove metallic iron-nickel alloy from the copper fractions. Distribution of cobalt was about 70 pct to the nickel fraction and 30 pct to the copper fraction. Silver reported predominately to the copper fraction, while Au, Pt, and Pd were essentially entirely recovered in the nickel fraction.

Jan 1, 1982

By S. D. Maksimovic

The Bureau of Mines identified and evaluated major sources of quartz dust during overburden drilling at a surface coal mine, The relative contribution of each source to the total dust hazard was estimated, using personal gravimetric and instantaneous dust-sampling devices. No attempt was made to determine actual dust generation rates. The major sources of dust at the drill rig during dry drilling opera-tions were the collector dump, drill shroud leakage, and drill stem seal leakage, These sources contributed 90 pct of the respirable dust and 89 pet of the respirable quartz dust generated during drilling, The collector dump cycle (21.6 pct of total drilling time) accounted for 38 pct of the respirable dust and 41 pct of the respirable quartz dust, with peak dust concentrations reaching 68 mg/m3. Shroud and drill stem leakage contributed 28 and 24 pct of the respirable dust and 32 and 16 pct of the respirable quartz dust, respectively. A dragline and second drill rig contributed the remaining 10 pct of dust and 11 pct of quartz dust. Gravimetric dust samples collected inside the drill cab and outside, near the cab door, averaged 1.65 and 1.43 mg/m3, respectively, with 6 pct respirable quartz.

Jan 1, 1985

By Tobias W. Goodman

The U.S. Bureau of Mines used a contact drilling strategy with short-collared assemblies in order to rotary drill long horizontal methane drainage holes in the Beckley Coalbed near Glen Daniel, WV. By decreasing the thrust, and increasing the rotation of the drill bit when in contact with the roof and floor rock, assemblies with 1-ft (0.3-m), 10-ft (3- m), and 144 (43-m) long collars were made in deflect and stay in the coalbed. Successful application of this procedure resulted in holes drilled full length in coal with the original assembly including bit. The test assemblies deflected away from the original bearings of the holes during drilling and arced. Four holes were drilled to depths ranging from 478 ft (145.7 m) before the strategy was developed, to 4,034 ft (1,230 m) when the strategy was applied. Total length of the holes in coal was 8,590 ft (2,618 m). After 577 days the total methane captured by the holes was 221,600,000 ft? (6,276,000 m3). The methane flow rate peaked at 805,000 ft3/d (22,798 m3/d), then decreased to stabilize at 670,000 ft?/d (18,974 m3/d) after 6 months.

Jan 1, 1989

It is now widely accepted that horizontal stress is present nearly everywhere underground. Often it is more severe than the vertical stress. It is a major cause of roof control problems in underground mines. The AHSEM computer program contains two modules to improve mine layouts for control of horizontal stress. For development, the user specifies the orientations of the maximum horizontal stress, the entries, and the crosscuts. Angled crosscuts may be used, and the angles may be different for the right- and left-hand crosscuts. AHSEM then shows the user how the stress condition would vary as the entry and crosscut orientations are changed. The second module is for longwall mining. Severe stress concentrations can make headgate conditions hazardous when the entries are improperly oriented. AHSEM shows whether a particular longwall orientation and extraction sequence places the headgate corner in a stress concentration or in stress relief. It also estimates the magnitude of the stress concentration.

Apr 1, 2003

By Jon C. Volkwein

Advances in mining technology have enabled deeper seams of coal to be mined from the surface. Highwall mining is frequently used to mine areas at the perimeters of a surface mine when removal of the overburden becomes uneconomical or threatens environmentally sensitive surface features. At the same time, advances in materials and technology have enabled highwall mining of coal that create blind headings over 300 meters in length. Deeper surface mining and deeper highwall penetration depths have lead to more frequent encounters with methane gas. While this coal is remotely mined from the surface, underground ignitions of methane have propagated to the surface and injured miners. Methods described in this paper show how this hazard can be correctly monitored and controlled for auger type highwall mining machines. Research indicates that small quantities of gas liberated during mining migrate to the face, creating higher gas concentrations than would otherwise be expected. Using the same principles that cause the gas to migrate to the face, researchers have shown that inert gas introduced at the collar of the hole can inert the entire hole, thus ensuring safe conditions for mining.

By D. Harrington, C. W. Owings

"The belief is now fairly general among the coal-mining people of the United States that one of the most effective methods of preventing wide-spread coalmine .explosions is that of introducing rock-dust into coal mines to reduce the inflammability or explosibility of dusts found on mine surfaces. Notwithstanding this belief it is improbable that even a small fraction of 1 per cent of the coal mines of the United States are at all adequately protected by rock-dust; in a survey made in the summer, and fall of 1927 it was found that but 463 out of more than 7,000 operating bituminous and lignitic coal mines were using rock-dust at all, and that few if any of the 463 were fully or adequately protected by rock-dusting.Inspections of a large number of mines through the United States by Bureau of Mines safety division field men have failed to reveal a single adequately rock-dusted mine, Yet there is no doubt that many of the owners and operators believed their properties to be fully protected by rock-dust against the much-feared hazard of widespread explosion. Two of the most disastrous explosions of recent years occurred at properties where the owners were definitely of the belief that the rock-dusting done had made the mines immune to widespread explosion involving coal-dust. In both instances it was found that although some rock-dusting had been done, the mines were more nearly 1 per cent than 100 per cent rock-dusted.This condition as to inefficiency or insufficiency of rock-dusting in the coal mines of the United States is almost universal, and unless our mining men awaken to its, dangers, the disaster record of the coal-mining industry is much more likely to become worse than better. During the fiscal year ended June 30, 1928, the attention of the safety division of the United States Bureau of Mines was called to. 22 explosions With 320 fatalities in bituminous coal mines of the United States; and of the 22 explosions there were 10 with 258 fatalities in mines that were listed as having used rock-dust; upon investigation it was found that as usual the rock-dusting had been anything but comprehensive or adequate. It is probable that in a very few instances last year the relatively small amount of rock-dusting stopped the .extension of the explosion and thus prevented further expansion of the death list. In general, however, the explosions occurred in a part of the mine that had not been rock-dusted - and right here is the crux of the failure or probable failure of present-day rock-dusting in the United States, There should be no part of any bituminous or coal mine in which all of the exposed surfaces (roof, ribs, and floor) have not been thoroughly rock-dusted and kept thoroughly rock-dusted. In other words, all exposed surfaces of all accessible places in bituminous and lignitic coal mines should be kept covered with rock-dust so that the combined rock-dust coal-dust mixture at all times and in all places has less than 35 or 40 per cent combustible matter, The only exception to this rule is that surfaces which are wet (and this does not mean merely damp) need not be rock-dusted. However, a mine opening may have several inches of water on the floor and yet have much explosive dust on the ribs and roof above the water; in such places the ribs and roof should be kept rock-dusted, irrespective of the wetness of the floor."

Nov 1, 1928