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By William D. Monaghan, Michael A. Trevits

Over the period 2000 to 2003, roof falls have accounted for 4 to 14% of the fatalities in underground mining operations. The National Institute for Occupational Safety and Health (NIOSH) is conducting research to reduce the frequency, exposure, and risk of these events through an ongoing program of field and laboratory studies. One area of research involves the evaluation of polyurethane grouting technology that is commonly used to stabilize fractured mine roof strata. Concurrently, NIOSH is conducting work to evaluate the application of ground penetrating radar for advanced delineation of problematic mining areas. In this study, NIOSH partnered with Sub-Technical, Inc. who injected a polyurethane grout (also known as glue) into a roof area of NIOSH’s Safety Research Coal Mine. The mine roof area was scanned using ground penetrating radar technology before and after grout injection in an attempt to determine the extent of grout infiltration. A comparison of the pre-and post-grouting radar records showed a significant change at a mine roof depth of about four to five feet. The interpreted radar records were then compared with drill core information, borescope evaluation of roof-bolt holes in the study area, and underground observations. At this site, the interpretations of the radar records correlated with data obtained from the core holes, borescope evaluations and underground observations. This study showed that ground penetrating radar technology can be a useful tool for detecting changes in mine roof due to the injection of the grout.

The question of earth models has repeatedly arisen in our work. An accurate representation of the seismic properties is required for three reasons: 1.To be able to determine from a set of received arrival times, the location of a seismic source in the earth, and secondly the degree of accuracy required in the model used for calculating source location from the set of arrival time differences. 2. To be able to determine the expected arrival times at an array of geophones produced in response to a hypothetical source in the earth. 3. To be able to estimate received signal strengths more accurately. The work reported here on earth models is based on information from sever- al consultants and from others who expressed an interest in the problem and supplied information to us. II. COAL MINE GEOLOGY On one of our earlier assignments for the Bureau of Mines, Earth Science Research Inc. of Cambridge, Massachusetts prepared for us a short description of the lithology to be expected at coal mine sites. This description follows, together with the ranges of compressional seismic velocities (Figure I*) associated with typical materials comprising the layered structure of a coal mine area. Coal is primarily associated with fresh water sediments including sandstones, shales, and clays, and occasionally may be metamorphased to varying degrees. In the Appalachian Basin the coal beds occur within cyclical sequences of non-marine shales, sands tones, conglomerates, limes tones, and clays. The beds range in thickness from a few inches to 60 feet, averaging between 2 feet and 10 feet. They have generally broad areal extent, occasionally up to 5,000 square miles, and have an overall tabular or lens-like shape. Within a particular lens, local changes in thickness are normal.

Jan 1, 1974

By Thomas H. Dubaniewicz

The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, conducted a study of past mine explosions to identify the ignition locations and ignition sources responsible for the most severe explosion events resulting in death. Since the Scotia disaster of 1976, many fatalities from underground coal mine explosions have been linked to nonpermissible electrical equipment ignition sources located in intake air courses. With few exceptions, explosion protected equipment is generally not required in intake air courses of gassy underground coal mines in the US. Cigarette lighters were another prevalent ignition source for fatal explosions ignited in intake air courses. Several mine rescue/ recovery teams have encountered electrical ignition hazards. The study provides evidence that intake air courses of gassy underground coal mines fit the description of certain Hazardous (classified) locations described in the US National Electrical Code®. Class I Division 2 or Zone 2 explosion protection tech¬niques may be used to design intake air equipment so that it does not present an ignition source under normal operation, before mine power is shut down in emergency situations. Nonpermissible circuits in intake air courses that are likely to remain energized during emergencies, e.g. battery powered equipment, should be protected by more stringent Class I Division 1, Zone 1, or Zone 0 techniques, to protect rescue/recovery personnel.

Jan 1, 2009

By F. P. Haver

The Bureau of Mines has investigated the electrochemical reduction of lead chloride as a method for producing lead without the pollution problems associated with smelting. It was determined that high-purity metal (>99.9 pct Pb) could be obtained, using PbC12 prepared by ferric chloride leaching of galena concentrate: PbS + 2FeCl3?PbCl2 + 2FeC12 + S°. Optimum results in small-scale electrolytic tests were achieved with a bath consisting of 40 to 70 wt-pct PbCl2 dissolved in KC1-LiCl eutectic, an operating temperature of 450° C, a current density of 2.5 amp/in2, and an electrode spacing of 0.5 inch. In large-scale tests made to develop a cell design for commercial application, the optimum electrode arrangement proved to be a bipolar configuration with horizontal plates. This gave a current efficiency of 86 pct with an energy requirement of 0.52 kwhr/lb lead. To determine the effect of impurity buildup in the bath, 1,200 lb of PbC12 prepared by ferric chloride leaching of galena concentrate was electrolyzed over a period of 2 months. Little deterioration of the metal quality occurred in that time; all of the lead produced had a purity equal to or better than corroding grade (>99.94 pct Pb).

Jan 1, 1976

By F. P. Haver

Because State and Federal agencies have limited the amount of sulfur oxides that can be discharged to the atmosphere, most copper smelters plan to convert the S02 in offgases to sulfuric acid. In some cases, however, it might be preferable to use a nonsmelting method to fix the sulfur in the form of a discardable product. Research by the Federal Bureau of Mines has shown that sulfur in copper concentrate can be converted into insoluble anhydrite (CaS04) by roasting the concentrate with lime (CaO). After leaching the calcine to recover metal values, the residue may be discarded without harm to the environment. The process can use a rougher flotation product, thus reducing separation costs and saving valuable minerals (for example, molybdenite) that are now lost in making cleaner concentrate. In tests, rougher concentrate was pelletized with the theoretical amount of lime and roasted for 1 hour in a 6-1/2-inch-ID by 11-foot-long rotary kiln at 700° C. Sulfur retention was about 97 percent. Leaching the calcine with 20 percent RCI extracted approximately 99 percent of the copper, 73 percent of the iron, and 91 percent of the molybdenum. After the molybdenum was removed from the leach solution by adsorption on activated carbon, copper with a purity in excess of 99 percent was obtained by cementation on sponge iron. The strip solution then could be spray-roasted at 500° C to recover the RCI for recycle and obtain F2O3 as a byproduct.

Jan 1, 1975

In the United States water pollution resulting from mining activities has long been recognized as a major environmental problem Mine drainage pollution results from many types of mining activities and includes both physical (i e , sedimentation) and chemical (i e , acidification, metal contamination, etc ) pollutants Active and abandoned surface and underground mines, mineral processing plants, mine and processing plant waste disposal areas, haulage roads, and tailing ponds are typical sources of mine related water pollution (130) One of the most serious pollution problems arising from mining activities is acid mine drainage resulting from the chemical reaction of sulfide minerals (commonly iron sulfides) and air in the presence of water Acid mine drainage is commonly associated with coal and hard rock mining areas in the United States In general the more serious and extensive acid mine drainage problems exist in the more humid coal regions east of the Mississippi River (11) In 1964 the U S Department of the Interior, Fish and Wildlife Service, reported that acid mine drainage adversely affected fish and wildlife habitat in 9,477 kilometers (5,890 miles) of streams and 6,062 hectares (14,967 acres) of impoundments in 20 states in the United States (64) Of the total affected waters, coal mining operations accounted for 97 percent of the acid mine drainage pollution reported for streams and 93 percent of that reported for impoundments In 1970 more than 19,308 kilometers (12,000 miles) of streams in the United States were reportedly significantly degraded by mining related pollution (130) Of the total affected kilometers, 16,920 kilometers (10,516 miles) or approximately 88 percent were located in the Appalachian coal region (Pennsylvania, West Virginia, Ohio, eastern Kentucky, Tennessee, Maryland, and Alabama) In addition, more than 965 kilometers (600 miles) of streams reportedly were degraded by coal mining in states in the Illinois, Western Interior, and Rocky Mountain coal regions The remaining portion of the stream pollution resulted from the mining of (1) copper (california, Montana, Nevada, New Hampshire, Tennessee, Virginia, and Wyoming), (2) lead and zinc (Colorado, Idaho, Kansas, Missouri, Montana, Oklahoma, and Tennessee), (3) uranium (Rocky Mountain States), (4) iron (Lake Superior iron region), (5) sand and gravel (all states), (6) phosphate (Florida and other states), (7) gold (Alaska), (8) bauxite and barite (Arkansas), and (9) molybdenum, gold, and other metals (Colorado) Abandoned mines and abandoned mine waste disposal areas contribute a large portion of the total pollution resulting from mining activities Numerous abandoned underground mines are located throughout the United States and many are discharging mine drainage pollutants In 1966 the U S Bureau of Mines estimated that more than 88,000 inactive and abandoned underground mines were in existance (126) A listing of these mines by state is presented in Table 1 0-1 More recent estimates indicate that this list is incomplete In Colorado alone there is

Jan 1, 1975

By A. C. Johnson

This paper is one of a series being prepared by the Bureau of Mines on exploration, development, mining methods and costs at various mines in the United States. It describes such methods at the Lincoln tungsten mine of the Wah Chang Mining Corp., Lincoln County, Nev. The purpose of these reports is to promote development and conservation of our mineral resources by disseminating technologic information on mining methods, practices and costs. The Lincoln mine in Lincoln County, Nev., in the southeastern part of the [tate], was acquired by the Wah Chang Mining Corp., in April 1951. Mining methods and costs are of special interest at this property because of the low costs and good production record achieved through a well planned program of exploration, development, and exploitation. Operations were discontinued in July 1957 after the Federal Government suspended the tungsten purchase program.

Jan 1, 1959

By Robert H. Merrill

This report summerizes the various studies made to determine the size and support of roofs in the upper shale formation, White Pine Copper Mine, Michigan. These studies were a cooperative effort of the White Pine Copper Company and the Federal Bureau of Mines. Before this investigation, the upper shale formation had been found to contain about 30 to 40 percent of the total mineralization in the ore zones. Investigators estimated that this shale could be economically mined by room-and-pillar methods, provided that the roof would stand over spans of 25 to 32 feet. The problem remained to determine the number of bolts required to safely support these spans. Unbonded fractures in the roof structure of the deposit complicated the use of laboratory methods for determining bolted roof support. Therefore, a method was devised to determine the in-place support which would consider the unbonded fractures. In this method the roofs of 3 rooms with spans of 20, 28, and 36 feet were intentionally overbolted as the rooms were mined. Following stability tests that sometimes exceeded 6 months, the bolts were selectively removed and roof sag, roof strain, and changes in bolt loads were measured concurrently. The number of bolts required for support of these spans was computed from these data.

Jan 1, 1961

By W. T. Millar

Field reconnaissance and laboratory tests on clay from South Windsor, Hartford County, Conn., indicate that the clay is suitable for lightweight aggregate raw material. Exploration of the deposit supports the conclusion that the reserves of clay are sufficient for economical mining operations to produce lightweight aggregate. Preliminary tests indicated that the clay has a short bloating range. Initial expansion occurred at 2,000° F, and at 2,100° F the clay was slightly overfired and sticky. Rotary kiln tests verified the preliminary data, and these tests showed that the clay would make a good lightweight aggregate if the processing temperature and the kiln feed sizes were closely controlled. Lightweight concrete made from the processed aggregate had properties comparable to those of concrete made from a commercial clay aggregate.

Jan 1, 1964

By J. F. Barkley

During the present war emergency, under the urge of the Federal Government to store coal, the following questions are frequently asked by coal users: (a) Will the coal lose any, of its heating value in storage? (b) Will it slack and give a smaller-size coal? (c) Will its burning characteristics change in any way? (d) Will it catch fire from spontaneous combustion? (e) What precautions should be taken when coal is stored? DISCUSSION (a) Loss of Heating Value Studies by the Bureau of Mines show that the loss of heating value of coal in storage commonly has been overestimated. Various types of storage tests were made on New River, Pocahontas, Pittsburgh gas, and Sheridan (Wyo.) coals. The following is quoted from Bureau of Mines Bulletin 136, Deterioration in the Heating Value of Coal During Storage, by H. C. Porter and F. K. Ovitz (p. 8):

Jan 1, 1943

By M. M. Fine

This report presents the results of laboratory mineral-dressing investigations by the Bureau of Mines of 14 individual or composite character samples from deposits in the Batesville manganese district. It will be noted that some concentrates have met or approached analytical specifications for metallurgical manganese ore although great variations in both physical and chemical composition from once deposit to another make each a new problem. In most cases it is evident that a substantial loss of manganese has occurred in the various slime and tailing products. An important aspect of this work is the research being conducted on manganese-bearing limestones. Recent reconnaissance indicates that this resource constitutes one of the major domestic reserves of manganese. Laboratory study has shown that ferrograde concentrates can be recovered from samples of manganese-bearing limestones from two properties. Research on samples from other areas is still underway.

Jan 1, 1957

By R. Carson Dalzell

The use of nuclear fission for chemical process heat offers the special advantage of high temperature, limited only by materials of construction. The process heat may be supplied economically at elevated pressures, since no compression of combustion air is required. For the initial effort in developing a high-temperature reactor, the indirect cycle, using helium as the heat-transfer medium, was chosen. The major problems are the design of high-temperature fuel elements, construction of an exchanger to transfer heat to process streams in the range of 2,500° F., and development of compressors capable of recycling helium at 1,000° F. and above. A conceptual design of a nuclear reactor to furnish process heat for coal gasification has been made. Spherical fuel elements utilizing a graphite structure, impregnated with uranium carbide fuel, were chosen, as spheres offer the possibility of easier loading and unloading of the reactor. Calculations of pressure drop and gas-pumping power for the system are included.

Jan 1, 1959

By Oliver C. Ralston

Nonmetallic technologic investigations of the U. S. Bureau of Mines are headquartered at experiment stations in three widely separated localities of the United States. During 1936, the Nonmetals Division of the Technologic Branch was formally set up by combining the direction off the work of these three experiment stations under one administration. The New Brunswick (N.J.) station which in the past has been known as the Nonmetallic Minerals Experiment Station, is henceforth to be at College Park, Md., as part of the Eastern Experiment Station, and its principal activities will be related to the nonmetallic resources of the Eastern and New England States.

Jan 1, 1937

By Maria I. De Rosa

The U.S. Bureau of Mines performed experiments to determine the embedded hydrogen chloride (HCI) and smoke particle characteristics during combustion of polyvinyl chloride (PVC) and chlorinated mine materials for development of a test parameter. The experiments were conducted in an approximately 20-L furnace at set furnace temperatures of 250° and 1,000° C, for a 14-min duration, with an airflow through the furnace of 10 L/min. The variables studied, as a function of time, were hydrogen chloride embedded on smoke particles, hydrogen chloride concentrations in the gas phase, smoke particle average diameter (dg) and particle concentration (no), and product of smoke particle diameter and concentration (dgno). Other variables included carbon monoxide (CO), carbon dioxide (CO2), and oxygen (O2) concentrations; sample mass weight loss; and furnace temperatures. Results show that there is a correlation between embedded hydrogen chloride, hydrogen chloride gas concentrations, and inverse of the smoke particle diameter-concentration product (1/dgno); the higher the hydrogen chloride gas concentrations, the higher the embedded hydrogen chloride, the higher the 1/(dgno) values. These correlations will enable development of a simple test parameter to assess the toxic hazard that these materials pose during fire.

Jan 1, 2010

By J. B. Zadra, S. M. Shelton, R. B. Fisher, M. M. Fine

"INTRODUCTION An extensive test program is in progress by the Bureau of Mines to determine ways and means of recovering ferromanganese ore 5/ from the widespread domestic manganese and manganiferous iron deposits.Samples were received from the Stance property in southwestern Virginia, 12 miles northwest of Stoney Gap, in Bland County.The Stange mine is situated on the crest of Flat Top Mountain and is developed by open-cuts extending over several acres. The manganese deposit occurs in the Oriskany sandstone largely as a replacement of the sandstone, to some extent as breccia filling in the crusted parts of the sandstone, and as veins along joints, and bedding planes.The mine was first worked in 1917 and was operated during the war years. A long period of idleness was followed by intermittent operations in recent years. A small log-washing plant, consisting of a 20-foot log washer, was operated 1-1/4 miles northwest of the mine. The log-washer concentrates were crushed to minus- 1/2 inch and then washed in a second log washer to remove as much of the siliceous sandstone as possible. According to a communication from the operator, the double-washed concentrates were jigged and the jig concentrates marketed without further beneficiation."

Apr 1, 1942

By J. W. Higgs

This paper, describing the operation of the Gifford Hill & Co. plant at Hoot Spur near Texarkana, is one of a series being prepared for and published by the United States Bureau of Mines on methods and costs of mining and preparing gravel and sand throughout the United States. These tapers are designed to disseminate technical information regarding the methods used. The cost tabulations represent local operating expenditures only and not total production costs. Although the publication of total costs might not be advisable in some instances yet a knowledge of operating costs is essential to the technical discussion and study of methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulation shall ensue. The plant described combines some features of dredging and some of dry-pit operation, as material is excavated in a dry pit with a drag line, hauled to the plant in standard-gage cars, and then pumped. This operation should be of special interest to operators whose deposits contain a large quantity of clay.

Jan 1, 1936

By R. W. Stahl

Coal mining has been revolutionized by the continuous miner. This machine has replaced, or has combined into 1, 3 former operations: Cutting, blasting, and loading. During the 25-year period before this machine was introduced, advances had been made in transportation, but the actual "coal getting" remained virtually the same. As frequently occurs, the multiple-purpose continuous miner introduced a new hazard--more rapid liberation of methane. The coal output formerly obtained from 10 to 20 working places might now be obtained from 1. It is true that circulation of air was generally increased; but the bulk of this machine virtually precludes continuous flow of air across the face, where gas may accumulate. Apprehension about this possible hazard led the Bureau of Mines to test face atmospheres during operation; and Report of Investigations 5288, Methane Buildup During Cutting and Continuous Mining Operations (published in 1956), presents proof that real danger may be present in many otherwise well ventilated mines.

Jan 1, 1958

By W. O. Vanderburg

This paper describing the methods of concentrating tungsten pros at the mills of the Atolia Mining Co. is one of a series of similar papers being prepared by the United States Bureau of Mines. The writer acknowledges the assistance and cooperation of A. V. Udell, president, Louis Warnken, bookkeeper, and C. K. Dennis, superintendent, of the Atolia Mining Co. in the preparation of this paper.

Jan 1, 1931

By T. H. Jeffers

To help maintain an adequate supply of minerals to meet national, economic, and strategic needs, the Bureau of Mines investigated the feasibility of extracting copper from coarse native copper ore with ammoniacal ammonium carbonate solution by a simulated in situ leaching procedure. A 5.9-metric-ton (6.5-ton) sample of minus 30.5-centimeter (12-inch) conglomerate-type ore analyzing 1.96 percent copper was leached in a column for 556 days with a solu-tion that contained, in grams per liter, 2.2 NBs and 1.9 CO[3=]. The copper extraction was 71.4 percent, and reagent consumptions were, in kilograms per metric ton of ore, 1.1 NBs and 0.85 CO[3=] (in pounds per ton of ore, 2.2 NH3 and 1.7 CO[3=]). The pregnant leach solutions contained about 1.4 grams per liter copper, which was readily extracted from these low-tenor liquors with a 1:19 mixture of an organic extractant and kerosine. Copper was stripped from the loaded organic with depleted electrolyte containing 150 grams per liter H2S04, and the copper was recovered by electrowinning with antimonial lead anodes. Conditions also were established for minimal lead transfer to the cathode copper.

Jan 1, 1979

By Steve W. Webb

The Bureau of Mines is researching a new technology for dewatering clay suspensions that consists of flocculation by high-molecular-weight poly-ethylene oxide (PEO) polymer and subsequent removal of water from the floes via a trommel. The minimum amount of PEO required to dewater the clays depends on the ions adsorbed on the surface of the elay particles. Infrared studies were performed on clays with Li+, NH4+, K+, Mg2+, Ca2+, Ba2+, or 8r2+ adsorbed, with and without adsorbed PEO, to develop data to aid in understanding the dewatering mechanism. Hydroxyl stretching modes between 3,400 and 3,250 em-I, associated with water adsorbed on the clay, showed changes in intensity proportional to the ionic eharge-to-radius ratio; that is, the ionic potential. In addition. a water-bending vibration of adsorbed water at 1,630 cm-1 showed variations associated with water desorption. The data are consistent with changes in adsorption of PEO resulting from variation of the acidity of water coordinated with the exchange ions, induced by the variation in field strength of the ions with the ionic potential.

Jan 1, 1986