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By John Plecash

This paper comprises a general outline of all of the developments, including the history, geology, mining, milling, power and transportation installations, at the gold mining operation of La Luz Mines Limited and the copper mining operation of its wholly-owned subsidiary, Rosita Mines Limited, both located in north-central Nicaragua. The low-grade, gold-bearing ore-bodies of La Luz Mines, contained in highly fractured and folded Lower Cretaceous sedimentary rocks, were from 1909 to 1928, mined and treated by primitive methods by the La Luz and Los Angeles Mining Company. The abandoned property was acquired by La Luz Mines Limited in 1936, and was equipped with modern machinery and put into production in 1939. Between 1939 and 1948, the daily rate of production was in-creased from 300 tons per day to 2,-000 ton per day. The ore reserves available for open-pit mining were depleted in 1954. Since then, the entire production has come from under-ground operations.

Jan 1, 1963

By M. C. Irani

This survey was conducted to determine the magnitude of the methane emission and control problem in U.S. bituminous coal mines. The resultant data indicate that the emission rate for any given coalbed depends primarily on the coal production rate and on mine depth, as well as on the nature of the coalbed and the surrounding strata. An excellent correlation was found between (1) the methane emission rate and (2) the product of coal production rate and mine depth for the mines in the Pittsburgh, Pocahontas Nos. 3 and 4, and the Illinois Nos. 5 and 6 coalbeds. The highest total emission rates found in U.S. bituminous coal mines were as follows, in million cubic feet per day: Monongalia County, W. Va., 39; Marion County, W. Va., 30.4; McDowell County, W. Va., 13.1; Washington County, Pa., 11.9; Greene County, Pa., 11.4; Buchanan County, Va., 21.6; Jefferson County, Ala., 10.3; and Franklin County, Ill., 6.6.

Jan 1, 1972

The 112th Annual National Western Mining Conference (NWMC) hosted by the Colorado Mining Association (CMA) drew some political heavyweights, if by voice only, into the fray of two of the hottest topics that the mining industry is currently facing ? climate change and the new energy economy. A changing political landscape in Colorado, as well as in Washington D.C., has given rise to questions about the economic future of the United States and the mining industry?s role in that future. While there has been a recent push away from traditional energy sources to a ?new energy economy? that is rich in renewable energy sources such as wind and solar, the NWMC?s agenda emphasized the role that minerals will play in new energy technologies. The conference was also full of talks about the industry?s role in reducing the United States? reliance on foreign oil and other mineral commodities. To that end, an impressive lineup of speakers were invited to attend the three-day conference Feb. 8-11, in Denver, CO. Unfortunately, Mother Nature had other plans and three of the four headliners, including Denver?s mayor and Democratic candidate for governor of Colorado, John Hickenlooper, were unable to get to the conference because of a massive blizzard on the East Coast locked them in Washington, D.C. However, with modern technology, a full auditorium heard presentations from Hickenlooper, National Mining Association (NMA) president and chief executive officer Hal Quinn and Glenn Kelly, vice president, government affairs for NMA. Republican candidate for governor of Colorado, Scott McInnis, did speak to the crowd in person.

Jan 4, 2010

By Rapheal Trousselle

For over 5 years, Davey Bickford has been developing and testing an electronic detonator blasting system. These new-technology detonators provide more accurate timing than conventional systems that rely on the combustion speed of a pyrotechnic composition.

Jan 1, 1997

By E. G. King

Thermodynamic calculations involving the oxides of tungsten and molybdenum have been hampered by lack of accurate entropies and high temperature heat contents. This paper presents work by the Federal Bureau of Mines on new low-temperature heat-capacity data leading to the evaluation of the 298.15° K. entropies of tungsten dioxide and tungsten trioxide, as well as high-temperature heat contents (above 298.15° K.) of molybdenum dioxide, molybdenum tri-oxide, tungsten dioxide, and tungsten trioxide. Included are heats of fusion of the two trioxides. The heats of formation at 298.15° K. of these four oxides are tabulated as measured by Mah4 5/ of this laboratory. Included also are the 298.15° K. entropy of Mo02 measured by Kin 6/ of this laboratory, and that for Mo03 according to Kelley and King.7/ These basic data provide a consistent compilation from which to perform accurate thermodynamic calculations involving these compounds. No previous low-temperature- heat-capacity measurements have been reported for tungsten dioxide. Seltz, Dunkerley, and DeWitt8/ measured the low-temperature heat capacity of tungsten trioxide. The only previously-reported high-temperature heat-content measurements for any of the oxides were conducted by Cosgrove and Snyder,9/ who measured molybdenum trioxide to 1,300° K.

Jan 1, 1960

By A. Baldwin

Reports technical progress in designing four machines to be used in mining coal underground, applying innovative concepts at the design stage (instead of add-ons). A study phase was followed by design activity, including calculations supporting the designs. Scale models of three machines were built, and a full-scale mock-up of the conventional loader was used to measure human factors parameters.

Jan 1, 1976

By E. D. Calvert

The room temperature tensile properties of commercially pure titanium and seven titanium alloys prepared by skull casting were determined in the as-cast and heat-treated conditions. Data were compared with property data from tensile tests on wrought alloys of the same compositions in the as-worked and heat-treated conditions. The alloys evaluated were Ti-5Al-2.5Sn, Ti-6Al-4V, Ti-6Al-4V-lSi, Ti-6A1-2Sn-4Zr-2Mo, Ti-6A1-6V-4Zr-4Mo, Ti-6A1-6V-2Sn, and Ti-11.5Mo-6Zr-4.5Sn. Test specimens were prepared from both static and centrifugal castings and from plate fabricated by forging and rolling vacuum-melted ingots. The data indicate that the alpha and alpha-beta alloys have strength properties in the as-cast condition that are reasonably close to the strength properties of their wrought counterparts in the as-worked condition. An exception to this was the Ti-6A1-6V-4Zr-4Mo alloy for which insufficient data were available to form any firm conclusions. Fine-grained cast structures of Beta III (Ti-11.5Mo-6Zr-4.5Sn) were shown to be generally stronger in the as-cast condition than the wrought alloy in the as-worked condition except for the yield strength of one structure that was unusually low. Heat treatment of this alloy produced properties that were unpredictable. Indications are, however, that optimization of heat treatment parameters for each cast structure could produce strength properties equal to that of wrought materials.

Jan 1, 1974

By W. Biermann

All industrial processes are economically driven, resulting in the ever increasing need for process optimization in order to stay competitive and profitable. Numerous models has been published depicting the optimization of the raw material usage in an arc furnace, as well as the thermal and electrical efficiency; however, to obtain a holistic view of the cost-effectiveness of the process one needs to expand the model to include the cost of all the operational variables. This project therefore aimed to not only include the raw material feeds and power consumption as input variables, but also the labour, maintenance, and environmental costs to generate an all-inclusive financial balance. In the end, the model was able to mathematically optimize the ferrochrome (FeCr) production process through evaluating the effect of a specified combination of input parameters. It could therefore be used as a tool to aid in managerial decision-making; to appraise and correspondingly adjust certain operational variables in order to achieve a maximum return on investment. This paper fully describes the reasoning behind the choice of the essential model components, the assumptions made during the models development, the calculation approach, as well as the advantages, limitations, possible applications, and areas for expansion of the final model. Through running simulations with plant data, it was found that the accuracy of final model remained fairly constant when applied to stable furnace conditions, but was met with a number of limitations when applied to more complex situations. These limitations could, however, be overcome through further development and expansion of the existing model to include a larger number of process variables.

Jan 1, 2012

By J. A. Bos, Z. Dai, P. Quinn, A. Lee

A flowsheet is being developed for processing Thompson ultramafic low-grade nickel ores. This type of ore is characterized by high content of serpentinized magnesium silicates which generate slimes during comminution. Flotation of this type of ore proves difficult due to problems associated with the slimes. The flowsheet, based on extensive laboratory and miniplant flotation tests, consists of two key components: desliming by hydrocyclones prior to flotation and using soda ash for pH control in flotation. Satisfactory metallurgical results have consistently been achieved in laboratory full circuit simulation and miniplant tests.

Jan 1, 2009

By Sang Ho Cho, Masaji Kato, Masaaki Yamamoto, Masaaki Nishi, Katsuhiko Kaneko

This paper presents a numerical simulation method to predict rock fragmentation and to verify a fracture mechanism by bench blasting. The rock fragmentation, which has been used as a means of the index to estimate the effect of bench blasting, affects the expenses for loading, conveyance and crushing of blasting muck piles. The developed numerical simulation method is based on the finite element method and fracture mechanics and includes the re-meshing procedure to express the fracture process of the rock mass. This paper discusses a procedure for a determination of size distributions of the results, which were calculated by numerical simulation, including the tines.

Jan 1, 2002

By C. R. McCann

The Bureau of Mines conducted an experimental study of conditions needed to produce flames of pulverized coal when the heat needed for ignition is sup-plied only from the flame and hot furnace refractory. An electrically heated furnace which burned about 1 pound of coal per hour was designed and fabricated. A sheath of air, surrounding the primary coal and air stream, was used to prevent entry of hot gases from recirculating combustion products. Furnace temperatures needed for ignition ranged from about 1,8300 F for an Illinois coal to 2,250° F for a Beckley seam coal. Apparent flame velocities were about 2 to 5 feet per second, increasing with volatile content of the coal and with distance from the burner mouth to the flame. The time required for ignition, approximately 0.02 to 0.07 sec, was a better measure of flame behavior than was velocity.

Jan 1, 1969

By Marcelo B. Mourao

Interactions of carbonaceous materials with liquid Fe-C melts have been investigated experimentally by determining the volatile yield due to rapid devolatilization (Flash Pyrolysis) and rates of dissolution at temperatures ranging from 1623 to 1873 K. The volatile yield increased with increasing the temperature. The comparison of results of different types of carbonaceous materials was possible by expressing the volatile yield in terms of Enhancement Factor, fE. The rates of dissolution of spectroscopic graphite and an industrial coke seemed to obey the correlation for natural convection under turbulent conditions. The experimental data for the graphite suggested that the rate of dissolution was controlled by the mass-transfer in the liquid boundary layer adjacent to the solid sample. The value for the empirical parameter correlating the dissolution coefficient and the operating variables was found to be 0.19 which was close to that reported in the literature. The comparison of the results obtained for the coke samples with those for the graphite revealed that the impurities and the porosity of the samples can effect the dissolution rates.

Jan 1, 1992

By Y. Rao, Y. Huang, G. Wang, W. Liu

The properties and deterioration in strength of cemented tailings backfill (CTB )in the underground acidic environment under oxidizing conditions were studied. X-ray diffraction analysis and scanning electron microscopy of the surface of the CTB was carried out, and the sulphuric acid corrosion mechanism elucidated. The properties tested included compressive strength, elastic modulus, cohesion, internal friction angle, variation in the hydrogen ion concentration, and stress-strain relationship in different corrosion periods. The damage model of the CTB was established considering the effects of parameters such as corrosion time and strain on the damage evolution. It was found that the compressive strength, elastic modulus, cohesion (binder effect), and internal friction angle increased at first and then decreased with exposure time. In the long term, the peak stress decreased with corrosion time while the peak strain increased; elastic modulus, and deformation modulus also decreased. The damage caused by corrosion and by load were related by means of a mathematical model, which revealed the relationships between sulphuric attack, load, and damage to backfill in complex underground environments. During corrosion, the expansion of gypsum and ettringite caused microfractures in the CTB. With increasing corrosion time, micro-cracks developed and proliferated. The mechanism of corrosion damage was found to be the dissolution of hydrogen ions and a sulphate ion reaction that produces an expansive substance, resulting in deterioration of the strength of CTB.

Jun 1, 2021

By Wils L. Cooley

The report covers tests and criteria for the establishment of safe grounding systems for coal mines. The work deals primarily with under-ground coal mines, but much is applicable to surface mines as well. Included is an extensive guide to grounding and bonding procedures for mine surface substations. Xit-Rods are evaluated and shown to deviate from manufacturer's claims. An analysis shows that very long cables are difficult to monitor using audio frequency ground-check techniques. A method is developed to detect failing cable splices without removing the cable from service. Simulation and measurement are compared for a technique to detect bad rail bonds, and an assessment is made of grounding techniques for dc face equipment.

Jan 1, 1979

By Kenneth M. Maas

The Bureau of Mines inventoried the land availability for mineral exploration and development in northern Alaska and compared this land with known mineral terranes and mineral deposits, to quantify the potential for favorable location of mining claims for metalliferous mineral deposits. This report includes thirty-three 1:500,000-scale maps that depict land availability, and the accompanying text and tables relate availability acreage to areas of favorable mineral terranes. Three categories of land availability and ownership are identified, along with 12 subcategories of land status. Available land comprises approximately 14.5 million acres or 16% of the 90.3-million-acre study area; land available with restrictions accounts for 7.5 million acres or 8%; and unavailable land encompasses 68.3 million acres or 76%. Mineral terranes underlie 37.8 million acres or 42% of the study area; 5.3 million acres or 14% are available for mineral location, 2.8 million acres or 7% are available with restrictions, and 29.7 million acres or 79% are unavailable. There are 500 known mineral deposits or occurrences within the study area. This includes 271 lode deposits, of which 171 lie within a recognized mineral terrane and 55 are on available land. The remaining 229 are placer deposits.

Jan 1, 1987

Process Simulation and Plant Design of a Mineral Selective Magnetising Flash Roasting Plant Using Neutrons

Sep 13, 2010

By J. M. Whiting

"North America has entered a period when greatly increased attention must be given to energy .supply and demand by government, industry and individuals. Such increasing concern about energy will be a long-term phenomenon, accompanied by continuing examination of future resource development and utilization. Those engaged in or associated with mining, a major energy consumer, are likely to experience a variety of problems which are associated with the end of an era of low-cost, virtually unlimited energy supply. Their efforts, furthermore, may be subjected to escalating public and government scrutiny, involvement and control. However, ever-growing recognition of the real and urgent necessity to systematically develop new energy supplies within Canada and the United States will provide unusual challenges and opportunities for those companies and individuals with mining expertise. The vast deposits of coal, tar sands and oil shale provide a relative certainty of supply which only stands to gain in attractive ness with time. In order to benefit from this aspect of certain supply, nevertheless, synthetic fuels will have to be produced at a tolerable cost. This will always require excellent process design and engineering. As synfuels development expands to any significant production level, however, and Jess than ideal reserves are scheduled, the usual geologic-productivity complexities encountered in making ore out of low-value rock will tend to become of prime concern. It is for this reason that the services of experienced mining personnel will be in growing demand in energy production."

Jan 1, 1973

By Patricio Santis, Jacopo Seccatore

Artisanal and Small-scale Mining (ASM) is a prominent activity in the extractive industry: considering only gold, it produces about 20% of world market supply. Despite this fact, ASM is generally associated with negative aspects of its environmental impact, and operational research is generally neglected. This paper emphasizes the peculiarity of the drilling and blasting systems of small underground mines in selected South American Countries. Such Countries, while having large mineral deposits and well recognized large-scale mining activities, at the same time still present on their territory ASM activities that are archaic, highly inefficient and dangerous for the safety of its operators. This paper documents drilling and blasting activities from gold mining in Ecuador and Chile. First, are described the outdated and often non-rational techniques employed by miners, to provide a general framework of the current methods. Then, it is shown what can be improved and how the current methods can be modified. Finally, are shown some field applications and the comparisons of the results obtained. One case shows how blast pull efficiency can be increased of from 82% to 98% by changing non-rational applications of explosive products. Another case shows how, by rationalizing blast designs, drilling and blasting costs can be reduced by 9% per month, the advance by blasting increased by 29% and the blasting efficiency increased from 70% to 90%. Finally, it is concluded that examples of application show how operational improvements are easily applicable on the field, relying only on tools and resources of artisanal mining, but combining solid engineering bases with confidence-gain and respect for the experience of the miners.

By Stuart Brashear, Eddie Colburn

The Birmingham Coal and Coke – Knight Mine is a single seam coal mine in central Alabama. As pit development progressed in 2013, concerns over increasing vibration levels resulted in modifications to the blasting program that inhibited shot size and coal recovery. By January 2014, while still over 1,400 feet (427 m) from the regulatory seismograph, vibration levels climbed above 70% of the mine permit limit, even with triple decking of holes and reduced burden and spacing. At this time the decision was made to commit to the use of signature waveform analysis and precision programmable electronic detonators to minimize vibration and maximize the amount of coal that could be recovered before vibration levels reached permit limits.

Jan 1, 2015

By S. Ndlovu, M. Malatse

"The Witwatersrand Basin is the heart of South Africa’a gold mining industry. The cluster of gold mines located in the Witwatersrand Basin generates a significant amount of mine tailings, which have adverse effects on the environment and ecological systems. In addition, disposal costs are very high. The exponential population growth in the Witwatersrand area has resulted in pressure on the reserves of traditional building materials. Quarrying for natural construction material is very expensive and damages the landscape. This work therefore examines the use of gold mine tailings in the production of bricks.Different mixing ratios of gold tailings, cement, and water were used. The resulting bricks were then cured in three different environments - sun dried, oven dried at 360°C, and cured in water for 24 hours. The bricks were then tested for unconfined compressive strength, water absorption, and weight loss. The results showed that the mixture with more cement than tailings had a compressive strength of approximately 530 kN/m2. It was also found that the best brick curing system was in a water environment. Bricks made from tailings cost more than conventional bricks because of the higher quantity of cement used, but the manufacturing process consumes less water. Overall, the results indicated that gold mine tailings have a high potential to substitute for the natural materials currently used in brickmaking.Paper written on project work carried out in partial fulfilment of BSc. Eng. (Metallurgyand Materials Sciences)"

Jan 1, 2015