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By Fred N. Kissell

Work done by Foster-Miller Associates under a Bureau of Mines research contract has developed methods to increase significantly the amount of fresh air that reaches the front of a continuous-mining machine. The emphasis was on removing methane build- ups that occur at the cutterhead. Using a full-scale plywood mockup of a coal mine working face area, the study showed that in many instances only about 20 pct of the fresh air heading towards an exhaust brattice or tubing actually gets to within 1 ft (0.3m) of the face. The key to providing more air at the face is to enhance and move forward the natural airflow pattern. This change in the natural airflow pattern can be accomplished by taking advantage of the air-moving abilities of the conventional water spray. It was discovered that if all the water sprays on the machine were realigned, then ventilation efficiencies of 70 pct or more were achieved regularly. This meant that if 9,000 cfm (4.2 m3/s) was entering the brattice, at least 6,300 cfm (3.0 m3/s) of this was reaching to within 1 ft (0.3m) of the face. This water spray realignment consists of placing a few nozzles on the side of the machine opposite the curtain and also tilting the front sprays slightly towards the curtain side. Recently, two underground tests and two additional independent laboratory tests of the water "Spray Fan" have been completed. In general, they have confirmed the performance of the Spray Fan system, but they also have provided useful information as to its difficulties and limitations.

Jan 1, 1980

By Virgil W. Carmichael

In the Fort Union formation of western North Dakota, eastern Montana and northeastern Wyoming there are immense tonnages of lignite and subbituminous coal that have not yet been evaluated in terms of present economic conditions. Continued expansion of United States energy requirements has focused ever increasing attention on this tremendous resource, particularly as efficiency in mining and transporting of coal, as well as in electrical energy generation and transmission have improved and as hydrogenation and gasification of coal approach economic feasibility. This "total energy" concept for coal includes all of the energy uses that coal offers and has resulted in mergers of oil and coal companies and acquisition of coal re- serves by oil companies, as well as by coal companies and others. There is no doubt that these coals are entering an exciting new era of exploration and development that will result in greatly increased production. As a matter of fact, increased consumption for energy generation is well under way and recognition of the economic feasibility of high-Btu pipeline gas and synthetic petroleum products from coal is imminent. As coal is gradually displaced in steam electric generation by the more exotic fuels and processes, it will be increasingly used as raw material for the synthetic petro-chemical industry and the organic chemical industry.

Jan 1, 1968

The US economy grew at a rate of 4% in 1994 and the gross domestic product rose to $6.74 trillion. With 261 million people - 605,000 in mining, including petroleum -the United States has l 10 million dwelling units and 200 million licensed motor vehicles. New private housing units authorized in 1994 rose 14% to 1.4 million units. New car production rose 11 % to 6.6 million units, while truck and bus production rose 30% to 5.2 million units. The inflation rate was less than 3% and the prime rate of interest averaged 7.15%. The producer price index (1982 = 100) for fuels and related products and power was down 4% to 78, while metals and metal products rose 5% to 125. Chemicals and allied products rose 3% to 132, and non-metallic mineral products rose 3% to 124. The merchandise trade deficit rose 25% to $166 billion. Disorder in the former Soviet Union led to substantial dumping of mineral materials. With vast mineral resources, the former Soviet Union land area totaled 22.4 million km2 (8.6 million sq miles). In comparison, the North Ameri¬can Free Trade Agreement (NAFTA) area (United States, Canada and Mexico) totals 21.4 million km2 (8.3 million sq miles).

Jan 1, 1995

By S. Atak, G. Bulut

The xanthate adsorption mechanism on pyrite was investigated with an emphasis on solubility studies. Additionally, adsorption studies, Eh and infrared spectrophotometer measurements were performed. Pyrite floats at pH levels between 3 and 6 using ethyl and amyl xanthates with a maximum at pH 4. The solubility of pyrite in the absence and presence of xanthate was investigated in detail with respect to pH and conditioning time. Experimental results showed that the solubility of pyrite increases from 60 to 120 ppm (10-3 to 2x10-3 mol/ L) in the presence of xanthate at pH 3. Fourier transform infrared (FTIR) spectra of ferric xanthate, dixanthogen and pyrite conditioned with xanthate indicated that dixanthogen is the only species that can be determined on the pyrite surface. Adsorption tests showed that the highest level of xanthate adsorption was in the acidic range; yet higher adsorption densities were detected in neutral solutions compared to alkaline conditions. Electrochemical data suggest that the doubling of the iron concentration is due to the reduction of ferric ion to ferrous by xanthate while xanthate is oxidized to dixanthogen. Dixanthogen formation together with the hydrophobic iron hydroxy-xanthate complex on the surface is proposed to be responsible for pyrite flotation. Key words: Flotation, Pyrite, Adsorption, Xanthate, Dixanthogen

Jan 1, 2003

By E. J. Onuscheck

With passage of the Federal coal' Mine Health and Safety Act of 1969, many challenges have been directed to the industry's mining and safety engineers. The most critical challenge is that of ventilation. The language concerning ventilation in many sections of the Act could very well deprive or limit the mining engineer in planning the ventilation for new mines, since the Act requires federal approval of all ventilation plans. Dependent upon approval and of course application of the law, this could, due to economics, prohibit the opening of new mines in some cases. Petitions for modification of some mandatory standards relating to ventilation have already been filed under Section 301(c). It is quite possible that many of these standards may be modified.

Jan 1, 1970

By John P. Dunford, Lewis A. Martin

Researchers from the Spokane Research Laboratory, National Institute for Occupational Safety and Health, in cooperation with engineers from the Department of Mining and Geological Engineering, Montana Tech, Butte, MT, conducted tests to evaluate the tensile strength, fiber count, and adhesion of shotcrete applied to panels at the Chief Joseph Mine, a research and training facility operated by Montana Tech. The tests were conducted in the mine ramp 45 m (150 ft) inward from the access portal at a 15.25-m- (50-ft) long test area divided into five 3-m- (10-ft) long sections. The shotcrete was applied with an Aliva 240.5 machine fitted with a predampener. Different amounts of fiber were entrained for each panel. Background data for the tests were obtained from earlier tests in Nevada, where the typical amount of fiber in the shotcrete is 6.54 kg/m3 (11 lb/yd3). All shotcrete was applied to a minimum thickness of 76 mm (3 in). Cylindrical cores were drilled at the wall-rock interface, and adhesion was tested after 28 days of curing. The goal of this research is to reduce the need to install multiple supports at the advancing face by creating a safer mining system that limits the time miners are exposed to unprotected roof.

Jan 1, 2005

By P. K. Naik, S. C. Das

Leaching studies of low-grade manganese ore containing 31.77% Mn and 23.71 % Fe from Nishikhal, India, were carried out using pyritiferous lignite as a reductant in sulfuric acid medium. The variables studied were quantity of lignite, sulfuric acid concentration and temperature. Regression equations for the extraction of manganese and potassium were determined from 23 full factorial design data. The experimental conditions for the extraction of manganese were optimized using the steepest-ascent method. It was found that 99.03% of the manganese could be extracted in three hours with an ore to lignite ratio of 1:1.8, a sulfuric acid concentration of 1.9 M and a temperature of 99°C. Key words: Leaching, Manganese ore, Lignite, Statistical design

Jan 1, 2003

By K. Fuenkajorn, J. J. K. Daeme

Ring tension tests have been conducted on 229 mm (9 in) diameter disks of Grande basaltic andesite and Pomona basalt with various center hole sizes in order to study the relationship between ring tensile strength and relative hole radius (hole radius/disk radius). The tensile strength, [ ] decreases as the relative hole radius, [ ] increases. A power equation, [ ] where C and R represent the coefficients of strength and shape, respectively, adequately represents the ring tensile strength as a function of relative hole radius over the range investigated. This equation can be used to distinguish the effect of the hole size from the strength results, to predict the tensile strength of a ring sample containing arbitrary hole sizes, and to approximate the critical relative hole radius of the material tested.

Jan 1, 1986

By E. Yuksel

Noted as one of the 20 major economies of the world, Turkey is a semi-arid plateau between the Eurasian and the African continents. With its surface area of 780 thousand sq km, it supports a population of 70 million people. While the mining history of Turkey can be traced back as far as 7 000 B.C., mining currently generates only 2% of Turkey’s gross national product. Turkey has 77 of the 90 principal minerals that are mined world-wide. Currently, some 5 000 mine occurrences including copper, lead, zinc, iron, gold-silver, chromite, sepiolite, mercury, and coal deposits, soda ash, marble, zeolite, feldspar, magnesite deposits, as well as the world’s largest known borate deposits, have been discovered and partially explored.

Jan 1, 2004

By Y. J. Wang

This paper describes a procedure for solving the generalized system of n network equations in n unknowns considering the following ventilation variables and parameters: (a) air quantities, (b) pressure losses or gains caused by the control devices (i.e., fans or regulators), (c) resistance factors, (d) natural ventilation pressure, and (e) fan pressures (as a function of air quantities). The air quantities and pressure losses for all branches in the network are grouped into dependent and independent variables. The branches with an independent quantity are contained in a chord set, and the branches with a dependent pressure loss are contained in a chord set. In addition to the problem formulation, the solution procedure, applying the Newton method, is discussed and illustrated with a numerical example.

Jan 1, 1989

By T. van Sandwijk, G. Van Weert, E. Molleman

This paper reports on test work that explored the dissolution/precipitation reaction: ZnS + 2HCl - ZnC12 + H2S, which is part of a process used in the production of pure ZnS. The research focused on the influence of proton activity on the dissolution of zinc concentrates obtained from the Brunswick Mine No. 12 in Canada (Brunswick Mining & Smelting); the Red Dog deposit in Alaska (Cominco Ltd.); and the Tara deposit in Ireland (Outukumpu Zinc). A comparison between the results of the experimental dissolution as a function of pH and the dissolution predicted by thermodynamics suggest that the three concentrates contained sig¬nificant amounts of the more reactive mineral wurtzite, although XRD analysis showed mainly the presence of the mineral sphalerite.

Jan 1, 1999

By Hugo J. Garcia, M. C. Fuerstenau, D. M. Lupan, J. L. Hendrix

Biodegradation of cyanide by microorganisms isolated from solids previously exposed to cyanide has been investigated. The anaerobic cyanide biodegradation showed good, short-term removal of cyanide in the presence of nutrients (medium A). This system retained metabolic activity at cyanide concentrations up to 300 ppm at pH 10.5. Microscopic examination of stained specimens revealed that the bacteria were Gram-negative, rod-shaped bacilli. Strains capable of cyanide decomposition were identified as Pseudomonas and Alcaligenes. The kinetics of biodegradation were found to be first order with respect to cyanide concentration, and the overall reaction rate constant is k = 0.102 day-1. Studies with Na14CN showed that 17 % of 14C transformation went into the cells, 18 % into carbonate and 47 % into bicarbonate.

Jan 1, 1995

By Jake Beale, Joe Wickline, M. Van Dyke, Ted M. Klemetti

A longwall coal mine in southwestern Virginia mining the Pocahontas #3 Coal Seam experienced a history of mining-related seismic events. The events were never large enough to cause concern until three major events occurred recording 3.4, 4.3, and 3.4 ML in 2005, 2006, and 2007 respectively. Two of the seismic events generated an air blast which damaged stoppings which fueled a mine fire in 2005 and 2007. The mine responded to the events by narrowing the longwall widths, changing ventilation controls, installing a 7-sensor seismic system around the active panel, and creating a mining hazard map to avoid similar geology in the future. All of the actions taken have prevented seismic activity from impacting mining operations, but it did not prevent other large seismic events from occurring (Van Dyke et al., 2018). In 2016, another large seismic event, measured at 3.7 ML, occurred in the gob that was reported by the local media and recorded by the United States Geological Survey (USGS). While the event did not directly impact mining operations, mine management wanted to know where and under what conditions could large seismic events occur in the future. The National Institute for Occupational Safety and Health (NIOSH) became involved to help understand what conditions precipitated these events so that future mine design could more accurately assess seismic hazards and reduce the risk to mine worker safety. Researchers at NIOSH and mine management created a seismic forecasting map that combined three factors: (1) overburden thickness, (2) sandstone thickness, and (3) the expected caving height of the gob. The criteria were developed based on the geologic data the mine collected from core drilling, e-log analysis, and fiberscope observations. The forecast map was able to provide an accuracy of 72%–85% of events 1.5 ML or greater and 100% accuracy of events that were 3.0 ML or greater based on historical data. The seismic forecasting map was applied to the entire future mining area to show areas where seismic potential could be the greatest based on current mine design planning, ultimately improving the ability of the mine operator to assess the seismic hazards surrounding active and future mining areas (Van Dyke et al. 2018). Following this research, the seismic forecasting map was implemented into the mine’s hazard recognition program and is continuously updated and evaluated prior to mining each longwall panel. This paper will cover in more detail how the seismic and lithologic data was processed and how the mine implemented a new seismic mitigation program based on the forecasting results.

Apr 26, 2022

By Frank W. Reinrniller

Mill ball charging systems have undergone little change during the past two decades. Most operations utilize a locomotive/ball car combination to load and haul charges from the ball storage bin to the mill charging boxes or, alternatively, transport charges to the charging boxes by means of a ball bucket handled by bridge crane. This paper describes a new concept in ball handling systems that is in operation at the Island Copper Concentrator of Utah Mines, Ltd. at Port Hardy, B.C. This system employs a narrow belt conveyor to convey a weighed charge to each of nine belt unloading stations at the mills. In operation, the system has proved to be practicable, trouble-free and economical of operating labor.

Jan 1, 1977

By Norman E. Breslow, John A. Montgomery, Sanford W. Horstman

Reconstruction of historical exposures to silica dust is required in an ongoing cohort mortality study of workers in the diatomaceous earth (DE) industry. However, historical data were collected using three different sampling methods. This study was conducted to derive empirical quantitative relationships from linear regression equations between the three methods: standard impinger, total mass, and respirable mass. Dust from one diatomaceous earth processing plant was sampled simultaneously by all three methods. Results from 61 clusters of the three sampling devices indicate that the phcle size distribution of the dust varies with the two parent products sampled. baghouse product and main product. The relationships between particle counts and respirable mass are: Respirable mass (mg/m3) = 0.064 (mppd) impinger count for baghouse product dust, and respirable mass (mg/m3) = 0.018 (mppcf) impinger count for main product dust. The relationships between particle counts and total mass are: Total mass (mg/m3) = 0.837 (mppcf) impinger count for baghouse product, and total mass (mg/m3) = 1.21 (mppcf) for main product dust. In all four euuations, the intercept did not differ significantly from zero, and the correlation coefficients ranged from 0.90 to 0.95. Results are compared with data from four previously published studies.

Jan 1, 1991

By Richard M. Crowell, John W. Shield

GeoBiotics has developed a biooxidation technology (patents pending) which involves coating refractory precious metal sulfide concentrates onto a support material and biooxidizing the sulfides in a heap configuration. The concentrates are produced from low or high grade sulfidic refractory ores or existing mine tailings. The process has been found to achieve high gold recoveries asso­ciated with stirred tank biooxidation, but at the low operating and capital costs associated with whole ore heap biooxidation. Improved gold recoveries of up to 98% after biooxidation are reported for 4 representative mines or deposits. The sulfide flotation concentrates were studied using 3 and 6 in. diameter columns or 3 in. drained vats. The refractory sulfide concen­trates biooxidize rapidly in 3 to 12 weeks with substantial increases in subsequent gold recovery.

Jan 1, 1996

By S. J. Schatzel, K. M. Ajayi, E. N. Rubinstein, Z. Khademian

This study simulates the impact of a shale gas well casing breach near a longwall mine. Field studies are conducted to measure mining-induced permeability changes over the abutment pillar of a longwall mine, and a geomechanical model is developed in 3DEC, a three-dimensional numerical modeling code, to predict the aperture of fractures in the overburden at the study site. The predicted aperture values are used to determine mining-induced permeabilities, and the results are compared with the field measurements. These aperture values are provided as inputs into fracture flow code (FFC), which generates a stochastic discrete fracture network (DFN) model for the study site and predicts the potential shale gas flow to the mine. Results from 100 DFN realizations are statistically analyzed using the bootstrapping method to compensate for notable variation in fracture geometry. The results show a significant difference between the gas inflow for nearby panels due to increase in the induced permeability during mining of the second panel. The average gas flow to the mine was calculated as 4.72 × 10 m3/s (49 cfm) for a hypothetical breach at the Sewickley horizon during the first panel mining, 8.97 × 10 m3/s (19 cfm) for a hypothetical breach at the Uniontown horizon during the first panel mining, 2.16 × 10 m3/s (458 cfm) for a hypothetical breach at the Sewickley horizon during the second panel mining, and 8.07 × 10 m3/s (171 cfm) for a hypothetical breach at the Uniontown horizon during the second panel mining. Depending on the mine ventilation system, this could result in methane concentrations exceeding regulatory limits. Hence, these findings provide insights into the potential risk of an unconventional gas well casing breach near a longwall mine under shallow cover.

Feb 1, 2024

By G. Vijaya Kumar, B. Srinivasa Rao, G. V. Krishna Rao

The paper outlines the ventilation practices prevailing in coal mines of Singareni Collieries Company (South India). The high annual average surface temperature and relatively steep geothermic gradient results in virgin strata temperatures in the region of 38- 42°C creating environmental problems in the working places. Expensive methods of air cooling can not be employed as the mines are small, and production and productivity do not justify the costs of artificial cooling of mine air. Controlled recirculation of mine air -- the unconventional technique being tried with success in some coal mines in U.K. has been analysed for improving the environmental conditions. The analysis shows that the method is safe, cost effective and can be applied with very little extra equipment.

Jan 1, 1991

By Chee Theng

"Getting minerals out of ores is messy, but mineral processors learn to have fun with it. Celebrating the innate joys of the industry was the theme of this year’s Colorado MPD Conference. At the same time, attendees dug deeper for insights into problems that continue to dog the community, including tailings dam crises, water resource challenges, and a dwindling number of academics to teach and train the workforce (see box).Tailings dam crisesMatt Fuller of Tierra Group International Ltd. brought some of the audience to tears with his impassioned talk on “The Infamous Legacy of Upstream Tailings Dams,” which won the conference’s Lou Cope award for best paper. The talk was especially poignant coming on the heels of the January tailings dam failure in Vale S.A.’s Córrego do Feijão iron ore mine in Brazil, the latest in a series of catastrophic dam failures over the past decade that includes the Fundão dam failure in 2015.Noting that the two dams share a common characteristic — both are upstream tailing dams — Fuller explained the three basic dam construction methods and why certain upstream tailing dams are susceptible to failure (Fig. 1). The downstream, centerline and upstream methods denote the direction the centerline of the dam crest moves with each successive raise in elevation of the dam. With the downstream dam, the foundation for future raises is essentially the same as that of the starter dam, he explained. With the centerline dam, half of the dam is constructed on the same foundation as the starter dam, and with the upstream dam, each successive raise is built out over the top of the tailings.“Downstream dams are expensive to build because each successive raise is bigger, so the sustaining capex to build them keeps growing,” Fuller said. Many decades ago, mine owners realized they could construct a starter dam, put their tailings through a hydrocyclone, generate a coarse sand fraction and stack the sand over the top of the tailings to build the next raise. “Then, there is no sustaining capex, it all comes out of operations,” Fuller added. The footprint is smaller, and it is a favorable means of retaining the tailings."

Jul 1, 2019

By G. Brofas

The reforestation potential of bauxite mining spoils by seeding was examined on this research work. The experimental plot was established on the location Strofi Koukouvista 5, Ghiona Mountain. The experiment consists of 3 species (Pinus nigra, Robinia pseudoacacia, and Spartium junceum) with 4 sowing treatments and 2 sowing seasons (autumn and spring). The treatments were: (1) broadcasting; (2) broadcasting and soil cultivation; (3) broadcasting with straw mulching and straw binding with asphalt emulsion; (4) broadcasting with soil cultivation, straw mulching and straw binding with asphalt emulsion. Third year results show that spring is better than autumn as a sowing season. Only the Spartium junceum species were found to germinate and survive in autumn. The results are better for all the species on the spring seeding. The most effective treatments for Robinia pseudoacacia and Pinus nigra are 3 and 4 while for the Spartium junceum even simple broadcasting shows good results although the best ones are achieved with treatments 2, 3 and 4. The paper?s findings show that reforestation by sowing could be effective for some species but further experimentation with other species is recommended. Concerning Robinia pseudoacacia, testing of different seed preparation treatments is needed in order to maximize the germination of seeds.

Jan 1, 2002