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To perform comprehensive economic evaluations on both existing and proposed mineral operations. Approach A comprehensive computer model was developed which is capable of evaluating the economics of an entire mineral recovery operation, including exploration, acquisition, infrastructure, mining, milling, smelting, refining, transportation, taxation, and return of and on capital. How it Works The MINSIM (MINe SIMulator) economic evaluation concept was developed by the Bureau of Mines in 1967. The initial versions used a continuous discounted cash flow rate-of-return (DCFROR) to measure the effect of changes in expected revenues and costs. Subsequent enhancements to the program have expanded and strengthened MINSIM, especially the addition of an option which determines total production cost (i.e., the commodity selling price that a mineral recovery operation would require in order to obtain a target rate of return), an expanded capacity for evaluating by-products from a mineral property, and significantly broadened taxation determining capabilities. The MINSIM computer program uses essentially the same procedures and calculations that are performed in a manual economic evaluation, although the program accomplishes its tasks much more rapidly and accurately, An experienced mineral economist may require a week to evaluate a single mining operation with the same detail and consistency provided by MINSIM in a matter of seconds of computer time.

Jan 1, 1983

By James H. Aase

Selected glacial lake clay deposits in Minnesota were sampled, tested, and evaluated to determine their suitability for use as a bonding agent in iron ore pellet manufacturing. Preliminary tests conducted on clay samples obtained from five ancient glacial lake basins identified the clays in the Lake Agassiz glacial lake basin near Cook, Minn., as having the greatest bonding potential. An auger drilling program was conducted to obtain substantial quantities of representative material for detailed testing. The drilling indicated the presence of large clay reserves in excess of 500 million tons within the 12-square-mile area investigated. Bench scale tests indicated that the bonding properties of Cook area clays, when activated with relatively small quantities of sodium carbonate monohydrate (Na2C03?H2O), imparted excellent strength characteristics to iron ore pellets. Larger scale continuous pelletizing tests were made to confirm the bench scale results. These tests indicated that use of 1 percent activated clay alone as binder gave the iron ore pellets an overall strength slightly lower than with 0.75 percent bentonite, considered the industry standard. Use of 0.5 percent activated clay plus 0.5 percent bentonite produced better pellet strength qualities than use of 0.75 percent bentonite alone, without increasing the silica plus alumina content. The data from both bench scale and larger scale continuous tests suggest that the Cook, Minn., clays can be utilized after activation either alone or in combination with bentonite at an economic advantage over present pelletizing practice with bentonite.

Jan 1, 1968

By Dennis A. Long

"The size of off-highway trucks has increased substantially over the last decade, bringing about a radical change in truck maintenance practices and procedures. As a result, surface mine maintenance mechanics today are faced with the increased hazards of working with larger and heavier tools and components and doing repairs at greater heights, thereby exposing them to a high potential for serious injury or death. Not surprisingly, the number of accidents involving truck maintenance mechanics is significantly increasing.The Bureau of Mines has assessed the haulage truck maintenance safety problem, analyzing maintenance-accident data over the 7-yr period, 1978- 84, in terms of personnel, job activities, truck components and systems, tools involved, and truck design. This assessment, based on the review and interpretation of 1,225 haulage truck maintenance accident reports, identified major factors contributing to these accidents. Overall, young, inexperienced workers are involved in most accidents. A typical maintenance accident involves a male mechanic under 33 yr old, with less than 5 yr job experience. INTRODUCTIONOver the past decade, surface mine maintenance and repair operations have changed radically. The number of maintenance personnel has grown along with the hazards of working with larger and heavier components at greater heights and with larger and heavier tools. Furthermore, transfer of skills from over-the-road vehicle mechanics is not as feasible as it once was, because of the ever increasing size of mining equipment and the complexity of its design. In short, surf ace mine equipment maintenance and repair has become increasingly sophisticated as well as labor intensive, necessitating further research and evaluation in terms of both safety and efficiency (1, 7-8) 2"

Jan 1, 1986

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

B 2 Program Use Instructions necessary to execute the program, after the card deck has been prepared, are summarized in the following. B 2. 1 Input Data Format Input data is supplied to the program in two ways a. By data cards that are read in after program compilation. b. By data specifications that are included within the program.

Jan 1, 1976

By Fred N. Kissell

Methane-flow and pressure data taken from a mine in the Pocahontas No. 3 coalbed are compared with flow rates from lump coal obtained in laboratory experiments. From this, it is concluded that the main source of gas is the intact coalbed rather than a "crushed zone" near the working face. The permeability and sorption capacity of the intact coalbed are calculated and gas emission rates are theoretically accounted for.

Jan 1, 1972

Engineering controls for overburden drilling include dry dust collection systems, wet dust suppression systems, and enclosed cabs [Zimmer and Lueck 1986; Volkwein et al. 1979]. Proper maintenance of the dust suppression system is critically important for drills using dry dust suppression methods. Failure to rigorously maintain these systems will result in inadequate dust control. Acute silicosis has been reported in miners operating equipment that relies on dry dust suppression [NOSH 1992].

Jan 1, 1997

By Thomas Varley

"Concentration, ore-dressing, or the dressing of minerals are common terms used in metallurgy and indicate processes of separating valuable minerals from worthless gangue. It is understood, of course, that the products from such processes, being separated from the various minerals and gangue, are ready for commercial sale or for further treatment by smelters and refineries.Gravity concentration takes advantage of the difference in specific gravity of the various constituent minerals and gangue of waste material in the ore. The two most common forms of concentration by this means are jigging and table concentration. Jigs usually are used in the separation of relatively coarse material and the tables for the finer material, the line of division in general being about 20 mesh.There are mar factors to be considered .before a decision can be made as to what method would be best adapted to the successful treatment of an ore and only by careful experiments can this be determined. Among the important factors to be considered are. The nature of the minerals present, their physical and chemical relations to the gangue material, and the gangue material itself. Perhaps the most important is the number of minerals present and their relation to each other.Metals exist in ores in three principal forms -- sulphides, oxides or carbonates, and native. Concentration by gravity methods is in general best suited to sulphide ores, although in some places considerable success has, been obtained in the concentration of oxide ores by gravity methods."

Apr 1, 1920

By Maria I. De Rosa

Table 19 and figure 7 show the number of fires and fire injuries for surface coal mines by state during 1990-1999. Table 19 also shows by state the risk rates, employees' working hours, lost workdays, and coal production. For surface coal mines, 215 fires occurred in 21 states during 1990-1999. Ninety-four of those fires caused 93 injuries and I fatality (the yearly average was 21.5 fires and 9.3 fire injuries). Fourteen fires and seven injuries involved contractors. The Ewhr value was 729 x 10° hr (In = 0.026), the CP value was 6,355 x 10° st (Fn = 0.034), and the LWD value was 8,141. Kentucky had the most fires and fire injuries (45 fires and 23 injuries), followed by Pennsylvania (33 fires and 14 injuries), West Virginia (25 fires and 14 injuries), and Indiana (20 fires and 8 injuries). Among these states, Pennsylvania had the highest fire risk rate value (Frr=0.145), while Kentucky had the highest injury risk rate value (In 0.041).

Jan 1, 2004

By M. M. Tilman

The Bureau of Mines investigated the precipitation strengthening of lead¬-base alloys containing 0.5 through 4 weight-percent combined Cd plus Sb. The Cd and Sb were alloyed in a 1-to-1 atomic ratio which maintained compositions along the quasi-binary section Pb-CdSb. Tensile properties, creep rates, and stress-rupture values were obtained on alloys in the aged condition. The highest tensile strength was observed in an alloy of Pb-3 CdSb, After aging for 6 months at 90°±3° F, this alloy had a mean tensile strength of 8,950 psi with 15-percent elongation. An aged alloy of Pb-1 CdSb exhibited a steady state creep rate of 1.2 X 10-3 percent per day at a stress of 500 psi and a temperature of 90°±3° F. Times to rupture at stresses up to 4,000 psi and at a temperature of 90°±3° F were obtained for some compositions.

Jan 1, 1970

By W. P. Rumancik, C. P. Lazzara, A. C. Smith

The United States Bureau of Mines (USBM) developed SPONCOM to aid in the assessment of the spontaneous combustion risk of an underground mining operation. A prior knowledge of the spontaneous combustion risk of the coal and factors that increase that risk can be useful in the planning and development of proactive monitoring, ventilation, and prevention plans for the mining operation. Interactive data input screens prompt the user for information about the coal's chemical and physical properties, the geologic and mining conditions encountered in the mining of the coal, and the mining practices employed. During the input process, 'expand' screens provide the user with specific information on each input parameter. This information includes a description of the parameter and its effect on the overall spontaneous combustion risk. The program logic determines the coal's relative spontaneous combustion potential, based on the coal's proximate and ultimate analyses, and heating value. The program then evaluates the impact of the coal properties, geologic and mining conditions, and mining practices on the spontaneous combustion risk of the mining operation. The program output provides details on each factor that increases the risk of spontaneous combustion.

Measure the leakage through individual crosscut stoppings quickly and economically so that the worst ones can be identified and repaired. (Typically 60 to 80% of the air supplied to a mine short circuits before reaching a working face.) Approach Most of the leakage through a permanent stop-ping is channeled through two windows in a temporary stopping, and air velocities through the windows are measured; leakage is determined from a formula. How It Works A temporary stopping made of plastic brattice is erected in the same cross cut as the permanent stopping, either upstream or downstream. The brattice is fastened to the roof, bottom, and ribs of the entry with spads. Normal leakage of brattice was allowed for in deriving formula, and does not effect results. For best accuracy the brattice and the stopping should be separated by a distance of one hydraulic diameter.

Jan 1, 1979

By Jack C. White

The Bureau of Mines, in its efforts to insure the continued viability of the domestic minerals economy, has been engaged for several years in research on the extraction of alumina from domestic, nonbauxitic resources. Hydrochloric acid leaching of kaolin is one of the more promising technologies being studied for recovering alumina for feedstock to existing aluminum smelting capacity; 93 pct of this feedstock is currently imported either as bauxite or alumina. Organics contamination of pregnant leach liquor, originating during solvent extraction for removal of iron from aluminum chloride solution formed during hydrochloric acid leaching, causes rapid deterioration of the semihard rubber lining of process equipment. These organics were removed by a skimming tank-coalescer-activated carbon adsorption system. Organic levels of less than 10 ppm from the coalescer and less than 0.5 ppm from carbon adsorption were achieved. Analytical methods employing CC14 extraction and infrared spectrophotometry were developed to determine the organic content of both the liquor and the carbon. Mass transfer zones delineated in the carbon columns provide adsorption data for the design of larger systems.

Jan 1, 1981

By C. M. K. Boldt

This U.S. Bureau of Mines report presents a study of three typical tailings samples as potential cemented backfill in underground mines. The testing series was unique in that the pulp densities of the samples were all above 75 pct solids. Test results included dry density; slump; percent settling after 28 days of curing; tensile strength after 28, 120, and 180 days of curing; and unconfined compressive strengths after 7, 28, 120, and 180 days of curing. The physical properties of the various test mixtures were further analyzed using linear and nonlinear statistical methods to produce correlations and mathematical equations. Physical properties were used to determine the influence of mix additives and as input for numerical modeling studies of backfill. The mathematical relations were used as a predictive tool in determining the suitability of various materials as backfill.

Jan 1, 1989

By J. R. Allsup

The Bureau of Mines studied the characteristics of simulated coal gas as an automotive fuel in two multicylinder vehicles in a standard and high-compression-ratio engine configuration. While using simulated coal gas fuel, increasing the engine compression ratio improved the fuel economy and vehicle performance but increased hydrocarbon emissions by 40 pct. photochemical reactivity of exhaust hydrocarbons was found to be extremely low using the coal gas fuel. An oxidizing catalyst used with the simulated coal gas fuel eliminated all but trace amounts of carbon monoxide and reactive hydrocarbons in the exhaust. Spark gap geometry and firing voltage were varied and, within the range tested, had little effect on vehicle performance and emissions using simulated coal gas fuel.

Jan 1, 1975

By S. D. Maksimovic

The Bureau of Mines evaluated the hydraulic stimulation of a gob-degasification borehole to determine if this procedure would aid in degasifying a longwall panel. The stimulated borehole did not degasify the longwall panel as expected either before or after mining of the panel started. It reduced the underground methane emission only 11 pct, considerably less than the reductions effected by two unstimulated boreholes in the same panel. Some probable reasons for the reduced methane flow from the hydraulically stimulated borehole are very low reservoir gas pressure, location of hydraulically stimulated zones within the grouted casing, a casing break caused by lateral shifting, possible vertical movement of rock strata during caving, grouting of a 4-inch pipe blocking three stimulated zones, plasticity of shales, and possible hole damage by swelling of water-sensitive minerals. The borehole was also located between two second-mined areas, which may have allowed partial degasification of the overburden and the coalbed in advance of mining. Finally, a period of 3 months is probably not long enough for the borehole to degasify the overburden before mining.

Jan 1, 1977

By Jürgen F. PH. D. Brune, Alex C. Smith, Michael A. Trevits

Underground coal mine fires in the United States continue to present a significant hazard to the safety and health of mine workers. The leading causes of mine fires include flame cutting and welding operations, frictional heating and ignitions, electrical shorts, mobile equipment malfunctions, and spontaneous combustion The National Institute for Occupational Safety and Health (NIOSH) is conducting an in-depth program of research to address mine fire prevention, early and reliable fire detection and mine fire suppression and control technologies. One segment of the research portfolio is focused on remote methods for addressing coal mine fires. This research is important because remote methods represent the primary means of fighting a mine fire when conditions are too dangerous to fight the fire directly underground. Technologies under investigation include remote methods for installing ventilation control devices (mine fire seals) and remote methods for suppressing the fire using, the injection of inert gas, gas-enhanced foam and jet engine exhaust gases into the fire zone. This paper presents a summary of remote mine firefighting technologies used in the U.S. and the results of completed NIOSH research.

By J. G. Walters

The method for predicting coke strength developed at Steinkohlenberg-bauverein, Germany, in which experimental parameters are readily determined by small-scale laboratory tests, was found to be applicable to cokes produced from industrially used blends of American coals. Predicted 1-inch ASTM tumbler indices for four industrial blends were found to be in excellent agreement with the experimentally determined values. The laboratory determined prediction parameters include the proximate analysis of the coal the size consist of the coal, and Ruhr dilatometer test data.

Jan 1, 1971

By J. C. Edwards

The Bureau of Mines developed a mathematical model that decribes the interaction of an automated breathing and metabolic simulator, or lung, with a self-contained· self-rescuer that is supplied compressed oxygen. The model can be used to predict the gas partial volumes of 0z, Nz, and COz in the lung and in the self-rescuer breathing bag for a prescribed metabolic state that characterizes the lung. Nonlinear rate equations are used to describe the temporal evolution of the gas partial volumes. A numerical procedure was established with a FORTRAN computer program to solve these equations, which correspond to a given metabolic state. Examples are presented of applications of the model to predict bag volume and bag oxygen concentration changes with time when the bag is controlled by an automated breathing simulator. Under certain restrictive conditions, the model equations can also be used to analytically pre-dict the time required for the bag to reach a maximum or minimum volume. The model equation in this latter case was extended to transi-tions between metabolic states, with transitions described as exponential growth or decay processes.

Jan 1, 1985

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

By I. D. Shah

Thermal decomposition of copper (II) sulfate (CUS04) and copper (II) oxy-sulfate (CuO?CUS04) are important steps in the overall oxidative roasting of covellite (CuS) and chalcocite (Cu2S). Nonisothermal thermogravimetric techniques were used to investigate the decomposition reactions in flowing Na and air. Thermal decomposition of CUS04 and CuO?CUS04 followed "linear" kinetics with an apparent activation energy of 55±2 and 66±3 kcal per mole decomposed, respectively. These apparent activation energies comply with those previously reported when isothermal kinetic techniques were used. The addition of oxygen decreased the rate of decomposition, while small amounts of iron which were admixed with CuO?CUS04 did not have a significant effect. Neither oxygen nor iron had any appreciable effect on the apparent activation energy of the decomposition reaction.

Jan 1, 1972