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By G. M. Potter, F. S. Wartman, M. D. Schmid

"In matte smelting of copper it has been established that the sulphpr present will combine with copper as long as the latter is present, and that thereafter it will combine with iron. The Cu-Fe ratio in the matte is determined by the Cu-S ratio, presumably owing to the much greater affinity of copper for sulphur or, expressed thermodynamically, the greater stability of copper sulphide in contact with silicate slag. Now, the work of Fournet and of Schütz, which is quoted in many elementary metallurgical texts, indicates that manganese ranks ahead of copper in its affinity for sulphur. Hence, we might expect that manganese could be concentrated from its admixture with iron. Compounds by matte smelting, and Rotts / has patented such a process. This greater affinity of manganese or sulphur is used to advantage in iron metallurgy, also, in which it is well-known that sulphur will combine with manganese and separate from metallic iron as manganese sulphide. Manganese sulphide,however, is quite soluble in silicate slags. 5/ The loss of manganese in slag in any attempted matte smelting is therefore great.If this solubility of manganese sulphide is slag is a physical one and the reaction MnO + FeS MnS + FeOIs substantially complete, then it might be expected that the addition of copper sulphide, which is almost entirety insoluble in slag, would serve to extract the manganese sulphide with the formation of a manganese-copper matte on the other hand, if an equilibrium exists in the above reaction, a copper sulphide layer would displace that equilibrium in one direction or the other, according to whether iron sulphide or manganese sulphide were more soluble in the matter layer."

May 1, 1937

By W. H. Young, R. L. Anderson

"Physical conditions, such as thickness and character of the coal seam, dip or pitch of the seam, depth of cover, character of roof and overlying strata, mine water, etc., affect the productivity in bituminous-coal mining. Thickness of the coal seam being mined is probably the most important single item that determines whether the output per man per day shall be low or high; however, in strip mining the depth of cover or overburden to be moved is of equal importance.Bituminous coal is mined today from seams of exceedingly variable thickness - less than 2 feet to more than 50 feet; however, a large majority of the mines are producing .coal from seams 3 to 6 feet thick. The average thickness of the coal seams mined in the United States has not changed materially in the past 25 years. The average seam thickness for all bituminous-coal mines was 63 inches in 1920 4/ and 65 inches in 19)45. As thick seams have been exhausted in the older fields, other thick seams, have been opened in the newer fields.Productivity increased from 4 net tons per man per day in 1920 to 5.78 in 1945. This 45 percent increase in productivity resulted from increased mechanization. The percentage of underground production represented by coal cut by machines increased from 61 in 1920 to 91 in 1945 Mechanical loading increased from less than 1 percent of underground production in 1920 to 56 percent in 1945, and strip mining increased from less than 2 percent to 19 percent of the total production during the same period."

Dec 1, 1947

By A. L. Murray, P. A. Surgeon

The Spring Canyon Mine Rescue Association is a cooperative association supported jointly by five coal-mining companies located in Spring Canyon, Utah. The properties of mining companies the Carbon Fuel Co, Rains , Utah, the Liberty Coal Co. , Latuda, Utah, the Standard Coal Co. , Standardville , Utan, the Spring Canyon Coal Co. , Storrs , Utah, and the Peerless Coal Co. , Peerless , Utah about a mile apart and normally employ a total of 915 men , 733 underground 182 on the surface . and The Association was organized on July 5, 1921 , and Rudolph Clark, fomerly first - aid miner on U. S. Bureau of Mines Rescue Car 11 , was placed in charge. as manager . A board of directors made up of a representative from each of the cooperating companies (usually the mine superintendent ) is the governing body of the Association and the expenses are prorated on a basis of the production of each of the five mines . The Association maintains eight sets of Gibbs rescue apparatus and a motor truck fitted up as a combined rescue truck and ambulance . Additional apparatus are to be purchased . Standardville is the central camp in the canyon and has been made the headquarters of the Association . The apparatus are now kept and the truck housed in a small station, but plans have been prepared for a large station which will be built this summer . This new station will have a large apparatus room , a test chamber, a suitable room. for training, and a garage on the first floor, while above will be the living quarters of the manager . There is a good road through the canyon and the other camps are all within two and one -half miles of Standardville .

May 1, 1922

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

"As movement or transportation of coal is second only in importance to actual mining, and as the latter is wholly dependent on the former, the efficiency of the haulage system often determines the efficiency of the entire plant. Safe or accident-free transportation is essential, also, because no attempt is made to divorce safety and efficiency, it being realized that they are inseparable.Most of the Ruhr mines were opened decades ago, and many features that were considered up-to-date then are now obsolete. Progress in developing haulage systems has been slow, chiefly because it would be very costly to change many to accomodate more modern equipment. These systems are being altered or modernized slowly, as capital permits. The only revolutionary changes that have been made in mine haulage are the use of larger locomo¬tives and cars, in the movement of shuttle cars, and in the adoption of skip hoisting. Most Ruhr shafts, however, will not accomodate large cars, the secondary roadways are too narrow for large locomotives, and the coal is too soft to permit skip hoisting because degradation would be too great. Therefore, notable advances have been made only at newer plants, where allowances have been made for modern equipment.The shafts are deep (average 2,300 feet) and of comparatively small diameter. The small bore was designed to reduce costs of sinking and lining. Generally, the shafts are lined throughout with masonry; however, most of the buntons and guides are wooden.The hoisting engines arc installed in masonry structures, and where more than one hoist is used they are placed on opposite sides of the shaft to eliminate as much noise as possible (fig. 1). This arrangement also prevents an engineer from acting on any signals except those transmitted to him. A few hoisting engines are mounted in the headframes (fig. 2). The hoisting engines are equipped with overwind, overspeed, and auxiliary braking devices, which are tested frequently and kept operative at all times. The signal code is displayed in view of the engineer, and a light or dial indicator informs him of the cage's position in the shaft. Many hoists are equipped with re¬cording devices, which show on a continuous chart the speed of hoisting as well as any delays throughout the 24-hour period.A Koepe system of winding is in general use because of the depth of shafts (fig. 3). With this system, a single rope passes over a single-groove, large-diameter sheave attached to the motive power, and the ends of the rope, after passing over the head sheaves, are attached to the cages. A flat tail rope suspended in the shaft and connected to the bottom of the cages serves to balance the system. Both steam and electric engines are used to activate the hoisting system, end the engines are capable of moving at least a 50-percent overload.The ropes are necessarily of large diameter (2-1/2 inches and greater), and flexibility decreases as rope diameter increases. To overcome the unwieldiness .of large-diameter ropes as shafts become deeper, a four-rope system is being tried at one mine (fig.4). In this system the load is equalized between four ropes which permits much smaller ropes to be used. All hoist ropes are inspected daily and discarded after 2 years service unless special permission for longer service is granted by the Mine Inspectorate, and then only after thorough visual and electromagnetic inspection."

Jan 1, 1950

Until man was able to produce light, his working day was pretty much limited to daylight hours. Underground miners have a special problem because in a mine it is just as dark during daytime as it is at night. The first devices used for mine lighting were torches and open flame 011 lamps. Torches made from twisted grass and dipped in tallow or pine pitch would burn for a while, but they made a lot of smoke and probably went out when they were needed most. During the 15001s, miners lamps consisted of a small metal dish with a hook attached to hang it up. The saucer-shaped dish was filled with animal or fish oil and a wick made of twisted fibers was laid In the 011 and hung over one edge where it would burn. This lamp would burn longer than a torch, but the amount of light cast by the pale, flickering flame was probably only a little better than no light at all.

Jan 1, 1976

By d&apos, Kathleen J. Amico

This summary appears in Minerals Yearbook volumes I and III, which cover mineral production in the United States, its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico, as well as the principal minerals imported into and exported from the United States. The several commodity and area chapters contain further details on production. A summary table comparing world and U.S. mineral production also is included. Mineral production may be measured at any of several stages of extraction and processing. The stage of measurement used in the chapter is normally what is termed "mine output." It usually refers to minerals in the form in which they are first extracted from the ground, but customarily includes for some minerals the product of auxiliary processing operations at or near mines.

Jan 1, 1967

By I. N. Beall

The present survey indicates 'that the average volatility of motor gasoline now being marketed throughout the country falls well within the limits of Federal Specifications. As would be expected, there is a slight decrease in volatility as compared with the gasoline marketed last wine:., but on the average the gasoline sold today is about the same as that sold last summer. During the past five years the Bureau of Mines has made semi-annual surveys of the gasoline marketed in the United States. To obtain a sample of each gasoline sold is obviously impracticable, but the cities in which samples have been collected have been so chosen as to be representative of the more important marketing territories. It is believed, therefore, that the samples obtained are indicative of the quality of gasoline marketed throughout the country.

Jan 1, 1925

The initial results from the magnetic sludge factorial experiment are summarized in Table 2. For ease in interpretation, the four separate variables are identified with the high and low level of each variable being represented by + and - signs, respectively. Several important relationships are evident from an inspection of the data in Table 2. For example, magnetic sludges were obtained only during the high temperature tests. Secondly, with the exception of the last three tests, there is an apparent correlation between settled sludge volume (or sludge settling rate) and pH. Data on residual dissolved Fee+ indicate that precipitation of iron is not complete at pH 8 and room temperature (Tests l, 3, 5, and 7). Although this should not have any confounding effect on the interpretation of the results, it is an important observation and an aspect of the overall conceptual process that should be considered carefully during any future developmental work. The data in Table 2 were employed more fully in the calculation of main effects and variable interactions for each of the three responses. For this purpose, a codified design and calculation matrix, shown in Table 3, was used. The derivation of this matrix is described by Davies.(9) The positive or negative signs for variable interactions are obtained simply by algebraic multiplication of the signs for each single variable involved in the interaction. Main effects and interactions are calculated by multiplying the response values (Table 2) by the corresponding effect elements (Table 3), summing the results, and dividing by 8. The resulting value for single variables is also sometimes designated as an average effect, since (for tyro levels of the variable only) it is simply the difference between the average response of all trials carried out at the first level of the variable (factor) and that of all trials at the second level. If the effect of one variable changes at different levels of another variable, the two variables are said to interact. The relative importance of the variable or variables in question is reflected by the absolute magnitude of the calculated main effect or interaction. First-order (two variable) interactions are usually easy to interpret in terms of the physical behavior of the system. Second- and higher-order interactions are often less readily understood, and are often of minor significance in any case. The main effects and interactions derived from the present study in the manner described above are listed in Table 4. It should be noted that

Jan 1, 1971

By Wallace W. Roepke, Jon I. Voltz

"The Bureau of Mines determined coal-cutting forces and primary dust generation of four styles of radial gage bits as used on end rings of continuous mining machines. Direct comparisons for reference were made with two widely used conical plumb-bob types having 60° and 90° (nominal) included tip angles. The cutting forces for all of the gage bits were similar to those of the 60°-tip plumb-bob bit. All bits except the RAD-3 gage bit generated similar amounts of primary total dust at shallow cutting, but during deeper cutting, the amounts varied and the gage bits produced as much as 2-1/2 times the dust produced by the 60° bit. This seems atypical since past experience has always shown differences in dust generation at shallow cutting. The specific energy was more like that found previously with other bits, since the values were spread at shallow cutting but became nearly similar at deeper cuts. The 90° bit and the RAD-3 gage bit are not recommended for use except in extremely difficult cutting conditions where dust and forces are of secondary importance. The choice among the remaining four bits can be made on the basis of dust, energy, forces, or cost, as circumstances dictate. INTRODUCTIONThe Federal Coal Mine Health and Safety Act of 1969, with revisions in 1977, was enacted to ensure more healthful and safer working conditions for miners. The Bureau of Mines coal-cutting research facility at Twin Cities (MN) is examining fundamental aspects of the cutting system, including generation of primary dust causing pneumoconiosis in miners and ignition of methane by the frictional impact of cutting bits used on continuous mining machines (CMM's). The cutting system is defined as the cutter-mineral interface area with all its variables, e.g., forces, speed, cutter geometry, bit-mounting geometry, and wear. It has become obvious over the past several years that the cutting system directly affects the economics and design of the ""total system,"" which is defined as all areas of the operation, from the mine face to the preparation plant, which support the mineral recovery by cutting tools to obtain a salable product."

Jan 1, 1983

GLOSSARY Acid- and toxic-forming materials. Rock or coal layers containing significant amounts of pyrite or other minerals which, if exposed by coal mining, will cause acid or toxic drainage to occur when acted upon by air and water. Add mine drainage. Any water with a pH less s than 6.0 draining from a coal mine. Water is often orange-colored because of the presence of oxidized iron. Adit. An underground mine entry at sites where coal seams are exposed at ground level. Apple core. A complete hilltop (360°) left exposed by not backfilling the highwall. Approximate original contour. The surface configuration achieved by backfilling and grading the mined area so that be reclaimed land closely resembles the general pre-mining surface configuration and blends into and complements the drainage pattern of the surrounding terrain. Area mining. A surface mining method that is carried on in level to gently rolling topography on relatively large tracts of land. Active area mine pits may be several miles long. Arid and semiarid regions. Lands, generally west t of We 100% meridian, where water use by native vegetation equals or exceeds that supplied by natural precipitation, and rainfall is insufficient to support agriculture. Annual precipitation is normally 20 inches or less. Auger mining. A mining technique often used by surface mine operators when the overburden becomes too for the coal to be mined economically using traditional surface mining methods. Large-diameter (usually 2'-4') horizontal holes are drilled as much as 300 feet into We vertical Me of the coal bed by an auger. Like a bit used for boring holes in wood, coal augers consist of a cutting head with a screw-like extension. As the auger turns, the head breaks up the coal and the screw carries it back into a conveyor that loads it directly into a truck. Backfilling. The operation of refilling an excavation using material removed during the mining process. Bench. The level or flat working area at the base of the highwall that is excavated between the exposed coal seam and the original surface of the ground. Bucket wheel excavator. A continuous-digging machine that uses a rotating vertical wheel with buckets for large-scale stripping and excavating. Cessation Order. Order to cease mining issued to a coal operator by the regulatory authority due to severity of violations, Contemporaneous reclamation. Restoration of mined land that occurs as soon as practical after coal removal. Contour mining. A mining method commonly used in eastern mountainous topography where coal is removed in a narrow strip around the hillside. The extent of the cut into the hillside is determined by the depth of overburden at the highwall compared with the thickness of the coal seam. Daylighting. A term used to describe a surface mining procedure that exposes abandoned underground coal mine workings to enable removal of the remaining coal. Daylighting is followed by land reclamation. Dragline. An excavating machine, usually used in large, flat areas, that drags a bucket (which holds up to 220 cubic yards of material) toward the machine by cables, loads it with spoil, and then hoists it wit a boom up to 350 feet long, allowing the machine to excavate wide benches by depositing the spoil hundreds of feet away from the highwall. Grading. The process of smoothing the disturbed areas of the mine site, after the coal is removed, to closely approximate the pre¬mining terrain. Haul road. Any road constructed, improved, maintained, or used by mine operators and located within the permit area. Head-of-hollow fill. See "valley rill." Highwall. The cliff-like excavated face of exposed overburden and coal in a surface mine. Hydroseeding. Planting of seed mixed in a water medium. Water, mulch, lime, fertilizer, and seed are blended and sprayed onto regarded soil.

Jan 1, 1992

By H. R. Grau

NIOSH’s Pittsburgh Research Laboratory is currently involved in research to identify silica dust generation in underground metal/nonmetal mines. The ultimate goal of this research is to develop control technologies to reduce worker exposure to respirable silica dust. Commodities and job classifications with the highest silica dust exposure have been identified through analysis of the Mine Safety and Health Administration (MSHA) compliance dust sampling database. Dust surveys were conducted in an underground limestone and gold mine to investigate silica dust sources, generation levels, and controls being used. A summary of the mining operations, sampling procedures, resulting data, and suggested methods to improve the dust control will be provided.

By D. R. Babich, E. R. Bauer

The U.S. National Institute for Occupational Safety and Health (NIOSH) is conducting a cross-sectional survey of equipment sound levels and worker noise exposures in the stone/aggregate mining industry. Six stone/aggregate mines (three surface and three underground) were recently surveyed, and the findings (ire presented here. The surveys consisted of sound-level measurements conducted around various equipment and machinery (including stone processing and crushing equipment) and full-shift dose measurements to determine worker noise exposures. The findings identify the equipment and machinery that are likely to cause worker overexposures and identify the workers found to he experiencing overexposures. In addition, the benefit of cabs in reducing mobile equipment operator noise exposure is discussed.

By B. W. Madsen

A nearly dormant copper sulfide pilot-scale experimental leach containing 8.7 tons of are was injected with oxygen to determine its effect on the copper-leaching rate. Prior treatment of the uncrushed 0.25-percent-copper, mine-run stripping material consisted of 461 days of acid ferric sulfate leaching, which extracted 47 percent of the total copper. The permeability of the bed had decreased, and the percolation rate had decreased from an initial 20 gallons to 0.8 gallon per square foot per day. Copper extraction had nearly stopped. After injecting oxygen into the ore column and leaching for 30 days, the percolation rate was increased to 6 gallons per square foot per day. In an additional 298 days of leaching, an additional 40.7 percent of the copper was extracted. The improved leaching after the use of oxygen is attributed to stimulated bacterial action, better oxidation, and increased permeability.

Jan 1, 1975

By R. E. Hall

When the criterion for control of scale prevention on the evaporating surfaces is made the conditions in the concentrated boiler water, then this control becomes an exact operation amenable to an accuracy commensurate with all other operations in the boiler room. The responsibility in boiler water conditioning, however, includes more than clean surfaces. Corrosion in feed lines, economizers and the boiler is a function of the condition of the later, and must be controlled. Steam line and turbine blading deposits must be obviated by the system of conditioning. By the chemical treatment employed, the amount and character of noncondensable uses in the steam must be controlled in accordance with the intended use of the steam. All. in all, the responsibility in boiler crater conditioning ends not with the entrance of the water into the boiler but with the passage from the boiler nozzle of steam, the dryness and rarity of which are defined by the uses to be made thereof. A clearer conception of the scope of boiler water conditioning can be obtained by reference to a diagram of the surfaces (Figure 1) at which it functions. Consideration of this diagram leads to the following outline for the problems of boiler water conditioning: (a) Prevention of scale formation on surfaces (1) In contact with water but at which no evaporation occurs. (2) At which evaporation is occurring.

Jan 1, 1926

By W. R. Reed

Drilling with water has the potential to significantly reduce the respirable dust concentrations generated from small-diameter rotary drills when drilling blastholes on surface mining operations. However, water adverseky affects tri- cone drill bits commonly used in surface drilling operations, causing excessive wear and premature replacement. Consequently, dry drilling with a dust collector system has the most widespread use in the industry. Tests have been conducted by the National Institute of Occupational Safety and Health (NOSH), Pittsburgh Research Laboratory (PRL) on a newly designed device for smaller diameter drills that separates the water from the bailing air before it reaches the bit and thus provides the cost benefit of dry drilling while providing the benefit of wet drilling for dust suppression. The water that is delivered to the hole with the bailing air is separated from the air by a proprietary mechanical device that is encased in a drill sub (short section of drill rod/pipe) located immediately behind the cutting bit. A cascade cyclone and a real-time dust monitor were used to sample dust emissions from the holes. Dust concentrations and silica content were measured when drilling dry versus drilling wet. The tests show that drilling with this water separating sub can reduce both measured dust emissions from the boreholes and visible dust around the drill rig.

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.

Develop a simple and economical technique for determining the absolute stresses and the change of stress on the surface of roofs, floors, or walls in miners. Approach Use a commercially-available, permissible, Whittemore-type gage to determine the stress at the surface of a mine opening and to monitor any stress changes that might take place. How It Works The following equipment is used: ? One steel templet (for laying out a 60° rosette on the: rock surface). See first photograph. ? One 3/8-inch rock drill bit for drilling holes for the rosette pins. ? Six stainless-steel rosette pins. ? One Whittemore-type mechanical strain gage. ? One drill (not shown). ? Epoxy for cementing the rosette pins. ? Tape to hold the pins while the epoxy sets. The following procedure is used to determine the absolute stress on the rock surface. 1) Spot the location of the rosette pins with the templet. 2) Drill the pin holes and set the pins with epoxy cement. 3) Measure and record the distance between the pins across three diameters of the rosette with a 10-inch Whittemore-type gage. See diagram. 4) Drill a 1 1/2-inch diameter hole in the center of the

Jan 1, 1981

By Robert K. Koch

Laboratory-scale studies on defluorination of natural and synthetic fluorspars by pyrohydrolysis at 1,500° C. were made to determine the feasibility of developing a process for producing hydrogen fluoride from siliceous fluorspars. It was found that the reaction (at 1,500° C.) is not promising for process development, even though a silica-free offgas can be generated. The primary difficulty is the low hydrogen fluoride content of the offgases; an HF content of 6 percent was the best achieved. Previous research by the Bureau of Mines has demonstrated that offgases averaging 27 percent hydrogen fluoride can be produced under carefully controlled conditions at 1,280° C. The lower temperature process is a better method for production of HF. However, charges in which the CaF to Si02 mole ratio varied from 0.4 to 2 could be processed with similar results. Also, combined alumina and ferric oxide contents up to 25 mole-percent did not noticeably alter the rate of defluorination. Therefore, virtually any natural siliceous fluorspar would respond in essentially the same manner when exposed to water vapor at 1,500° C.

Jan 1, 1962

By R. V. Ramani, A. S. C. Owili-eger

A mass balance equation can be written for the unit block of Figure 7 for changes within the volume during time At as: [ ] where x and y are the coordinates; q is the flow across any surface; p is the density of the fluid flowing through the medium; qvol is the volumetric flowrate; @ is the medium porosity; and Ax and Ay are the dimensions of the block. The subscripts t and (t+At) denote time levels and At is the change in time. Writing this equation in nota- tional form and on rearranging, the following expression is obtained:

Jan 1, 1974

By D. Eugene Rannels, Yu-Chen Lee, John W. Swisher

"Inhaled dust particles of appropriate size contact cells of the alveolar region.' The acute response to coal dust appears to involve a variety of cell types, including alveolar epithelial cells, interstitial fibroblasts, both resident and recruited macrophages, and cells of the immune system. Direct and indirect effects of dust, which may be mediated by soluble factors,'' can initiate acute and long-term lung injury. While it appears that epithelial cell growth and differentiation, along with integrity of the epithelial basement membrane, may play a role in the long-term response to dust exposure, little is known of the role the alveolar epithelium may play in the progression of injury. The broad hypothesis that underlies these experiments is that short- and long-term consequences of coal dust exposure involve changes in structure and function of the alveolar epithelium and the underlying extracellular matrix. Recent studies show that coal dusts exert direct effects to modify pulmonary epithelial cell-extracellular matrix interactions in vitro.3EXPERIMENTAL PROCEDURESType II cells isolated on day 0 by density centrifugation and differential attachment4 were plated overnight in D MEM containing 10% fetal calf serum before exposure to anthracite dust PSOC 867 sonicated into culture medium (750 ug/mL).3 Synthesis of extracellular matrix proteins was determined on day 3 of primary culture, as detailed elsewhere. 5 Cells were removed from extracellular matrix by extraction with NH4OH and high salt. Extracellular matrix synthesis and fibronectin content were evaluated based on radiolabeling with 3 H-leucine and on Western blot analysis, respectively. Additional analytical methods and calculations are detailed elsewhere.3-5"

Jan 1, 1998