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By Daniel C. Boteler

Data from 68 entrained-bed carbonization tests were treated statistically by the Bureau of Mines, and several useful relationships were developed among the major variables. Nine coals, ranging in rank from lignite A to high-volatile A bituminous, were carbonized in two entrained-bed carbonization pilot plants. The carbonizing reactors employed were vertically mounted cylinders, internally heated, refractory-lined, and 10 inches ID. The range of carbonization temperatures was from 825° to 1,600° F. Using a regression-analysis computer program, empirical equations were developed by which carbonization temperature, air-to-coal ratio, devolatilization of coal, char yield, and volatile matter content of product char may be predicted.

Jan 1, 1973

By A. E. Raddatz

The Federal Bureau of Mines, as part of its goal to minimize undesirable environmental impacts associated with mineral processing, has investigated a soda-smelting technique for processing ilmenite into pig iron and a titanium slag that is suitable for a feed to a sulfate-process titania pigment plant. By this procedure, the generation of ferrous sulfate waste and its associated disposal problem is obviated. Molten titania slag was quenched, water leached, and filtered to yield a sodium titanate intermediate product containing about 70 wt-pct Ti02, 1 wt-pct Fe, and 20 wt-pct Na20. This intermediate product, high-soda titanate (HST), was mixed with H2S04, calcined, quenched, and water leached to produce a low-soda titanate (LST) product that contained only 2 wt-pct Na20. Both the HST and LST were evaluated as feed materials for preparing titania by the sulfate process. About 95 pct of the Ti02 was extracted from HST and LST by digestion in concentrated or 50-wt-pct-H2S204 solutions. About 95 pct of the solubilized Ti02 was subsequently recovered from the titanyl sulfate solutions by hydrolysis. Barren solutions from hydrolysis, containing about 26-wt-pct H2S04, were upgraded by vacuum-thermal evaporation or electrodialysis. The regenerated acid solutions were used to digest additional HST and LST.

Jan 1, 1979

By George S. Rice, L. C. IlsLey

"A remarkable explosion of fire-damp caused by a discharge of lightning at the new shaft at the Sitalpur coal mine, has been reported by the Chief Inspector of Mines of India, who gave the following details:""The explosion occurred during a thunderstorm, and the evidence showed that a flash of lightning had, to all appearances, passed down the shaft caus¬ing disruptive discharges at certain points between the guides and the winding rope, rending the latter at two places situated respectively .228 .feet and 278 feet from the surface, The distance between the winding rope and the side of the shaft was 5 feet 4 inches, indicating a spark gap ;of this width, and an intensity of discharge which could not fail to ignite the explosive mixture of gas and air known to be present in the shaft.""The Compressed Air Magazine, January 1920 issue, which contained the above extract also goes on to state;""In 1915, M, Ferey described in a paper read before the Societe de l'Industrie Minerale phenomena of a similar character to the above. In a pit liable to sudden outbursts of gas, for the sake of safety, shot firing was carried out from the surface. During a storm, in the year 1905, shots went off in two places after the detonators had been connected to the conductors) we read in the Colliery Guardian, London. These shots were situated respectively 1,400 and 1,410 metres from the firing station, Realizing the possible danger from this cause, the precaution was taken to cut the conductors at the bottom of the shaft and to connect there just before firing, Even under these conditions a shot went off spontaneously, -.owing, it is believed, to lightning."""

Feb 1, 1920

To recover metals as sulfide concentrates from contaminated waste streams using hydrogen sulfide (H2S) generated by the bacterial digestion of waste organic materials. Approach The goal of this research is to develop a treatment method for metal mine effluents that will rival the cost and convenience of conventional lime treatment, and that will provide better effluent water quality, result in less expensive sludge disposal, and allow for the selective recovery of metals.

Jan 1, 1993

By R. W. Stahl, H. E. Sanford, J. B. Benson

Immediately following the capitulation of Germany in World War II, the German State was occupied by various allied forces, who supervised all indus- trial activities in the area. Coal production is vital to the industrial life of Germany, and most of the coal is mined in the American- and British- occupied zones of western Germany. The British-occupied zones include the Aachen and Ruhr districts, from which approximately 90 percent of the coal is obtained. Figure 1 is a map of the Ruhr district. Because of the magni- tude of the task of insuring an adequate supply of coal and the necessity for united action, it was deemed best to reorganize the coal-producing facilities in the British zone undor the joint supervision of American and British authorities. As a result, the UK/US Coal Control Group was established accord- ing to the organization plan indicated in figure 2. Headquarters for the group was established at Essen, in Villa Huegol, the prewar home of the Krupp family (fig. 3). One of the many problems recognized immediately by the UK/US Coal Control Group was the necessity of preventing disasters and reducing accidents to work- men in mines undor military-governmont control. Consequently, the United States Bureau of Mines was requested to furnish the services of qualified men to search for the hazards incident to coal mining and to prepare comprehensive reports on the results of their investigations. The authors, who wore selected for this task, spont about a year in Germany and visited all except a few of the smaller mince. Whereas their principal purpose was to investi- gate safety conditions, somo of the operating conditions and practices also wore studied. The results of the studies and investigations are embodied in this circular with the hope that some useful information will be disseminated to the mining industry of the United States, including supervisory officials, safety directors, engineers, and mine workmon.

Feb 1, 1950

By Wesley T. Holmes II, Lloyd H. Banning

Electric - smelting studies were made on titaniferous materials obtained from the Klukwan and Snettisham , Alaska ; Choteau , Mont .; and Iron Mountain , Wyo . , deposits with the objective of determining the feasibility of producing pig iron and an enriched titania slag in one test series and pig iron alone in another test series . In addition , related studies were conducted to determine the amenability of Choteau crude ore to wet -magnetic separation and to determine the quality of steel that could be produced from the titaniferous pig iron . The continuous smelting tests were made in a three - phase , submerged - arc , electric furnace , and the laboratory steelmaking tests were made in a singlephase electric - arc furnace . A continuous , belt - type , wet - magnetic separator was used in conjunction with a ball mill and a spiral classifier in recovering titaniferous magnetite from the crude Choteau ore . Pig irons containing less than 0.05 percent phosphorus or sulfur were readily produced from the titaniferous materials ; iron recoveries ranged from 92 to 98 percent . The Choteau ore was ground to minus 65 - mesh to produce a concentrate containing 60 percent or more iron . The steel produced from the titaniferous pig iron was a high - quality product .

Jan 1, 1964

By T. G. Carnahan

The Bureau of Mines conducted laboratory-scale weathering research on a leach residue containing elemental sulfur and mixed metal sulfides. Experiments were performed to determine pH and impurity element concentrations in the effluents as functions of time and to determine the effects on effluent concentrations of mixing the residue with dolomite tailing material. Four 800-day tests were conducted simultaneously. Soluble metal concentrations, especially zinc and copper, were excessive in the effluents from washed and unwashed samples of the residue. Concentrations of up to 20 g/l of Zn and 12 g/l of Cu were obtained. The pH values of the unwashed and washed residue effluents at the completion of the experiments were 2.8 and 1.9, respectively. Sulfuric acid from oxidation of pyrite caused the pH decrease. Mixing unwashed residue with dolomite tailing to maintain a near-neutral pH minimized the heavy metals content in the effluents. The pH in the dolomite tests increased slowly after the first 360 days and attained values of 7.8 and 8.2, respectively, for tailing containing 1 pct leach residue and for tailing devoid of leach residue. Dissolved zinc and copper did not exceed 0.10 g/l of Zn and 0.001 g/l of Cu.

Jan 1, 1982

By M. K. Larson, J. K. Whyatt, R. B. Langston, J. C. Johnson, H. Kirsten, T. M. Brady

An experiment is described in which hollow inclusion cells (HICells) were used to measure stress in a jointed rock mass during drift development at the Stillwater Mine, Nye, MT, USA. Two HICells were installed in the footwall approximately two drift widths ahead of the face. One HICell was over cored and then immediately tested in a biaxial chamber. The other HICell was left in place and monitored as the drift was excavated in three advances, each one-half the width of the drift. Strains were recorded hourly by a datalogger. Results show that there was little stress change during the first and second drift advances, but that a large stress change occurred after the third advance. The measurements also showed that the in situ principal stress directions lined up with regional geologic structures. Stress changes during face advance were likely caused by deformation along localized joint sets and inelastic deformation near the face.

Provide an economic alternative to drill-blast excavation with the same ability to excavate openings of varied orientation, shape, and size. Approach Develop an efficient, adaptable, mechanical excavation machine that produces unconfined tensile failure in rock. How It Works A drill-split fragmentation machine that combines a drill and a unique splitter has been developed. The drill and splitter are mounted on a carriage that positions the splitter in a hole immediately after it is made by the drill. The splitter creates force loads that cause the rock to fragment, and the process is repeated for excavation. The unique splitter applies both radial and axial loads to the rock mass, which produces an excavation action comparable to pulling a plug. This excavation action distinguishes the radial-axial splitter from typical demolition splitters, which require a free surface parallel to the axis of the splitter toward which to break rock.

Jan 1, 1989

Reduce costs of recontouring surface mined land by improving bulldozer blades. Approach A specialized 48-foot-wide bulldozer blade set at an angle, a 13-foot bulldozer blade with swept-forward end sections, and a 24-foot grading bar are used in conjunction with conventional bulldozers to reduce the cost of recontouring surface mined land. How They Work The angle blade is used to do the initial and intermediate leveling of long spoil banks. It is mounted at an angle on two 410-horsepower crawler tractors in a side-by-side offset configuration, but requires only one operator since both tractors are controlled by a single set of controls. The angle blade usually begins its cycle at one end of the spoil bank where the operator fills the blade and moves forward, continuously cutting and casting the material to the repose slope. At the opposite end of the spall bank, the angle blade turns around and begins cut-ting and casting material to the opposite repose slope. This action continues until adjacent banks meet or the lateral distance from the center line of the spoil bank to the repose slope exceeds approximately 40 to 50 feet. At this distance, the sidecasting angle blade is no longer effective, and conventional bulldozers are used to do the final land shaping.

Jan 1, 1981

Reduce dust on long wall faces by using a gob curtain to lower air leakage Into the gob and raise the airflow along the face. Approach A brattice curtain (gob curtain) Is hung between shield #1 and the rib in the headgate entry forcing the ventilating air stream to make the 90° turn and stay on the face side of the shields rather than leaking into the gob. How It Works Air leakage is greatest in the headgate area because the gob behind the first few shields remains open due to the roof bolts in the headgate entry. In addition to the open gob, there is a large gap between shield #1 and the rib. Prevention of air leakage behind the shields is accomplished by the Installation of a curtain between the first shield and the rib extending from the roof to the bottom. The curtain Is advanced with the shield line each pass and is helpful In maintaining a sufficient air quantity along the face. The biggest Improvement due to this curtain is seen in the first 25-30 shields where the Increased air volume lowers dust concentrations through dilution.

Jan 1, 1981

By Edward L. McHugh

Digital camera and computer technologies can be used to monitor mine slopes and provide real-time warning of rock falls. NIOSH researchers assembled a surveillance system using low-cost video cameras and computer software from the security industry to test its effectiveness. The system is designed to signal an alarm when motion is detected and to record images of the scene. Masking can restrict motion detection to specific areas within the camera view; sensitivity is adjustable. The time-stamped images provide a record that can help reconstruct and quantify an event. Video motion detection can augment standard monitoring methods to increase safety in surface mines.

By William H. Lewis

This paper describes the Bureau of Mines efforts in the research and development of a new and innovative mine lighting system which is based on fiber optics technology. The new lighting concept offers significant advantages over conventional systems in the areas of both safety and long- term maintenance costs. An overview of Bureau research into the problems and limitations of present-day mine lighting systems is also presented.

By E. C. Lane

The motor gasoline that is being marketed in the United States this winter (1928-29) is slightly more volatile than that gold a year ago. This characteristic is shown by a slight lowering of the distillation temperatures, particularly at the average initial and 20 per cent boiling points. Daring the past mine and a half years the Bureau of Mines has made semi annual surreys of the gasoline marketed in the United States; the Survey just completed is the nineteenth in the series. The 12 cities in which samples have been collected were chosen as representative of the more important marketing territories, as it was obviously impracticable to obtain a sample of every gasoline sold in the entire country.

Jan 1, 1929

Reduce costs of surface mine reclamation by improving bulldozer operating efficiency. Approach A draft power indicating system helps bulldozer operators adjust blade height and other controls for maximum load movement, by continuously indicating the rate at which work is being done. How It Works This system continuously measures both the push of the blade against the overburden, and the true ground velocity of the bulldozer. It multiplies those quantities to determine the real work rate of the machine. The system consists of a velocity sensor, a blade load sensor, processing circuits, and a work-rate indicator. The processing circuits include an analog multiplier which has an output signal representing the draft power (velocity x load = power). The draft power, or pushing power is a measurement of the work rate at that moment.

Jan 1, 1979

By H. E. Sanford

"INTRODUCTION Of the occupations in and about coal mines, those of the haulage crews are among the most hazardous. Statistics indicate that the second largest number of fatalities about coal mines occurs during haulage operations and through the use or misuse of haulage equipment. Despite the fact that relatively few coal-mine employees are engaged continuously at haulage operations, approximately 20 percent of all coal-mine fatalities are attributable to haulage.Most of the hazards in haulage operations could be very greatly reduced if more serious consideration were given to the problems of the haulage crews and if sincere efforts were made to reduce the hazards. Underground haulage is similar in many respects to railroading; yet, railroading is now considered one of the safest of occupations a distinction that has been attained only by honest effort and whole-hearted cooperation on the part of all concerned. Underground haulage is also similar to street and highway operation and has in it some of the difficulties encountered in the reduction of traffic accidents the seriousness of which has not by any means been con¬trolled as yet, notwithstanding the fact that much effort has been expended through a multiplicity of laws, ordinance regulation, etc., as well as by thousands of enforcement agencies and officers.The men working on the locomotives are among the most important members of a coal-mine organization; without skilled haulage employees, the production of coal would be greatly retarded. Their jobs, particularly the job as brakeman, require physical endurance, agility, and mental and physical alertness; in thin coal beds, especially where the roof is not brushed and the coal is loaded into mine cars by hand, the need for these qualifications is greatly increased."

May 1, 1948

By J. Roger Loebenstein

This report presents a U.S. Bureau of Mines study of the flow of arsenic-containing materials in the United States, based on the best data available in 1991, includes a consideration of arsenic as a byproduct of the processing of nonferrous metals, the fate of arsenic in manufacturing wastes, the quantity of arsenic used in products, tile fate of arsenic in dissipative uses, and the useful life of discarded products. Where possible, estimates are given of the amounts of arsenic lost from the materials flow. Arsenic byproduct of mining nonferrous metals. Historically, most U.S. production has been from the states of Montana, Washington, and Utah. The smelters in these states are believed to be the areas of the country where arsenic is most concentrated in the soil, tailings ponds, and waste dumps. Since the closure of the last domestic producer of arsenic in 1985, all arsenic has been derived from imported sources. Historically, arsenic was important in agricultural applications as an insecticide, herbicide, and cotton desiccant. As the environmental movement gained momentum and the toxicity of arsenic became better understood, most of the agricultural uses for arsenic were banned. Beginning about 1975, the use of arsenic as a wood preservative began to grow. After 1980, wood preservative uses became more important than agricultural applications. By 1990, 70% of the arsenic consumed in the United States was used by the wood preservative industry and 20% by the agricultural industry. The major source of domestic arsenic emissions in 1989 was from the U.S. copper processing indus¬try. About 7,800 mt/yr of arsenic was discarded in leach dumps, tailings, and slag. Another 800 mt/yr was liberated to the atmosphere and 1/100 mt/yr was exported in copper concentrates. On the consumption side, 9,200 mt/yr was lost, mostly from dissipative agricultural uses and the disposal of obsolete arsenical products.

Jan 1, 1994

By Stephen C. Tadolini, Thomas M. Barczak

Roof support systems, longwall shields in particular, have persistently grown in size and capacity for the past 25 years. Why is this? Is it a good thing or is it unnecessary? What are the consequences of this “bigger-the-better” design philosophy? Rarely do we see a “one size fits all” approach to roof support except when it comes to longwall shields, where the historical trend for new procurements is to simply purchase the highest capacity support you can buy. Does high capacity ensure failures will not occur? The answer is no! The highest capacity tailgate supports are typically the ones that fail the most often. What does this tell us? It tells us that there are fundamental aspects of support design and ground control that we still do not understand or recognize when designing a support system. This paper provides an interesting evaluation of these issues and proposes a different approach to support design that attempts to match the support performance characteristics to the ground behavior. Along the way, some of the old premises of support design will be discarded, and new “controversial” ideas developed. Thinking outside the box never hurt any industry. Mining has made it a common practice.

Aluminum alloys are used in two broad classifications: wrought and cast. Wrought alloy products, which are formed into final shape by rolling, forging, extruding. etc., contain low percentages of alloying elements; whereas cast aluminum products, which generally are not worked before use, may contain higher percentages and a somewhat different selection of alloying elements. For example, wrought aluminum alloys usually contain less than one percent silicon and cast alloys contain as much as 18 per-cent silicon. While there are good techniques available for separating aluminum alloys from mixed scrap, there are no efficient ways to separate wrought aluminum from cast aluminum. The high levels of silicon, iron) copper, and zinc from the cast alloys make wrought-cast mixtures unacceptable for wrought alloy production. Consequently, separated wrought aluminum scrap commands a premium price on the market. Since increasing amounts of mixed aluminum alloys are being recovered from automobile scrap, this separation is important for efficient recycling of these alloys. Approach The difference in thermo-mechanical properties between the two classes of aluminum alloys is used as the basis for the separation process. Casting alloys lose their ductility within a certain temperature range while wrought alloys remain ductile. As temperature increases, aluminum alloys gradually become weaker, and at a certain temperature, each alloy loses strength and ductility due to incipient melting in localized areas. For casting alloys that temperature generally lies between 520° to 560° C, but it is above 600° C for most wrought alloys. Mild crushing, therefore, in the proper temperature range will result in complete fragmentation of the casting alloys but only plastic deformation of the wrought alloys. A simple screening step then is used to separate the oversize wrought pieces from the fragmented cast alloys.

Jan 1, 1984

By Thomas C. Ruhe

The Bureau of Mines conducted research to determine the safe operating conditions for using recycled (used) lubricating oil from mining equipment as a partial replacement for diesel fuel to make ANFO-type blasting agents. The use of recycled oil (RO) saves energy, reduces oil imports, and reduces mining costs. Low ambient temperatures may cause these recycled oils to become too viscous for proper absorption by ammonium nitrate (AN) prills and result in poor blast performance, safety hazards, and environmental problems. To help quantify and resolve these issues, viscosity, mixing, and performance tests were conducted at various temperatures. Diesel fuels No. 1 and No. 2 were studied separately and in blends with 25,50, and 75% RO. Good quality ANFO mixes (94-6) were produced with dry absorbent prills and blended fuel (No. 1 diesel plus RO) at temperatures as low as -40°F (-40°C) with 75% No. 1/25% RO, and at -20°F (-29°C) with 50/50. Diesel fuel No. 2 also made good mixes as low as -30" F (-34°C) with 75% No. 2/25% RO, and at 0°F (-18°C) with 50/50.

Jan 1, 2008