Search Documents

By Kelvin K. Wu, George H. Gardner

On July 24, 2002, a nonfatal entrapment accident occurred at the Quecreek #1 Mine, Black Wolf Coal Company, when an active mining section inadvertently cut into a flooded abandoned mine. This incident, and the dramatic rescue which ensued, brought national attention to a common problem in the coal mining industry. Since 1995, there have been more than 100 inundations at coal mines in the United States. Unavailable, inaccurate, or incomplete mapping of older abandoned mines is typically responsible. Serious problems associated with accidental discharges of fluid mine waste material (slurry) and water from coal refuse disposal facilities have resulted from similar causes. Recent problems related to the inaccurate location of old abandoned mine works have increased the interest in the use of conventional and emerging drilling and geophysical techniques for detection of air-filled and water-filled cavities. The United States Congress has committed significant funding toward investigating the applicability of these technologies. MSHA actively promotes the use of the best available technology to minimize the significant adverse safety and environmental consequences associated with unplanned breakthroughs and inundations. This paper provides background information and a general summary of the MSHA-sponsored field demonstration projects which are currently in progress. Potential benefits and limitations are discussed. The need for field verification/ground-truthing is emphasized. Under appropriate conditions, geophysical methods can be effectively integrated into a comprehensive field exploration program.

Jan 1, 2005

By C. K. Man

Coal dust explosions in underground coal mines are prevented by generous application of rock dust (usually limestone). If an explosion should occur, the rock dust disperses, mixes with the coal dust and prevents flame propagation by acting as a thermal inhibitor or heat sink. To investigate this process in more detail, a number of explosion experiments using various coal dust and limestone rock dust mixes have been carried out at the Lake Lynn Experimental Mine (LLEM). These were conducted in a single entry of about 1600 ft (488m) in length and initiated with a methane gas explosion. A consistent set of post-explosion floor dust samples were taken along the entry after each test. These dust samples have been analyzed in the laboratory using thermogravimetric analysis (TGA) and solubility to determine how the limestone rock dust behaved during the coal dust / rock dust explosions. The preliminary results are reported in this paper and indicate that the chemistry of limestone plays an important role in its capacity to inhibit coal dust explosions. The results also show that it may be possible to estimate the intensity of the explosion using these conventional methods of analysis. Disclaimer: The findings and conclusions in this report have not been formally disseminated by the National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy.

Jan 1, 2009

Iron removal using biologically produced organic acids was investigated as a treatment option for the production of refractory grade bauxite. A leaching solution containing 98mM oxalic and 67mM citric acid was prepared from a sucrose medium using for fermentation the fungus Aspergillus niger. The leaching capacity of the metabolic product was tested on a bauxite sample containing 16-19% iron (as Fe2O3). Aerobic and anaerobic leaching tests were carried out at pH 3, 50°C and in the absence of light. Results indicated that more than 80% of total Fe can be removed from the ore, when the sample is finely ground and applying a two stage treatment. The presence of oxygen was seen to affect adversely the kinetics of the process, suggesting that leaching follows a reductive mechanism. Experiments that were carried out with different particle size fractions indicated that for obtaining efficient removal of iron particles should be finer than 0.63mm. Reduction of the operating temperature from 50 to 30°C caused a decrease in the rate of iron removal by more than 10 times.

Jan 1, 2006

By Robert M. Miller, Judy Milligan

A computerized "Decision Support System" was used to evaluate an "Underground Platform Approach to Oil Recovery". Over a billion calculations were required to model the mine layouts; learning curves for shaft, tunnel, and well drilling scenarios; detailed cost, schedule, and resource data; complex oil production and material balance data; varying reservoir parameters; and complex oil pricing curves. Simplified "optimum" solutions were defined in terms of muck hoisting capacity, barrels of oil per day, and present worth. Complex "optimum" solutions were defined in terms of minimal exposure scenarios during development followed by shortest time to full production.

Jan 1, 1987

By Ali Jaberi Zamharir, Abolfazl Shoghian‐Alanaghi, Hossein Aghajani, Arvin Taghizadeh Tabrizi

In this study, the leaching rate of molybdenite concentrate was evaluated in sulfuric medium, and the influence of the diverse oxidants including hydrogen peroxide, manganese oxide, copper sulfate on the leaching rate was studied. Also, the effect of the addition of the ethylene glycol to the hydrogen peroxide was studied and results showed that with the addition of ethylene glycol, the leaching rate is increased 55% from 41% up to 80.3%. The optimum condition is achieved as 0.7 M of H2SO4, 4.4 M of H2O2, and 3.5 M of EG at 30 °C within 4 h of leaching time and 500 rpm. Also, inserting the oxygen with the pressure of 6 bar to the leaching autoclave, the leaching rate is increased more up to 86.4%. Finally, the leaching process was studied kinetically and the determined mode of controlling factor was specified based on the activation energy which equals 46.252 kJ/mole indicating the chemical reaction mode.

Jun 5, 2022

By Z. Hyder

Simulation and modeling is powerful tool to analyze real time data and can be used to analyze different scenarios using appropriate software that may reduce need of infield data collection process and can predict reasonably accurate results. In this paper the real time data of a mine is used to simulate and model the stresses on the pillars and evaluate the pillar strength and safety factor. The material properties assigned to the model are obtained by testing the representative samples taken from the selected locations of the mine. The mine under investigation has 50 ft wide pillars and 50 ft wide rooms under an average overburden of 650 feet. The effect of reduced pillar dimensions and increased roof span on overall stability of mine and extraction ratio is analyzed using LaModel [1] software. The predicted results of the reducing pillar size are analyzed to compares the current mining practices with the optimized room and pillar size to get better extraction ratio without comprising the safety.

Jan 1, 2011

By W. A. Wilkinson

Mining companies today are under increasing pressure to boost output from their existing mines and to bring new projects online quickly. Fundamental to the long-term performance of an operation is geologic modeling and mine planning. To maximize mine profitability, planners and schedulers must account for a staggering array of variables and create accurate mining plans that meet production and profit targets. Not surprisingly, this can be a difficult task, and getting it wrong can result in large unforeseen costs and significant lost revenue opportunities. This paper discusses the top five challenges geologists and engineers are facing in developing mining plans.

Jan 1, 2012

By M. Lohk, Y. -. R. Pastarus

Oil shale industry of Estonia provides a significant contribution to the country’s economy, but causes a large number of different problems. In spite of high economical parameters of the current underground mining (room-and-pillar) technology it is not effective. Backfill technology will be applicable in condition of Estonian oil shale mines. Nowadays attention has been focused on the use of combustion and mining by-products as filling materials. Use of ash and limestone in mining industry is treated as a part of mining technology, not as a waste disposal. Underground utilization of wastes reduces the volume and area required for surface disposal, environmental taxes. It improves the quality of mining works. The use of backfill technology has great impact on mining practice in Estonian oil shale industry.

Jan 1, 2011

By F. J. Klingler, R. Hausmann, K. M. Swaffar, J. C. Neyer

This paper presents the results of a study of case histories of projects on which sinking caissons were used to construct shafts for tunnel construction and other underground works. Design methodologies are reviewed with respect to the impact of soil and groundwater conditions on the performance and constructability of sinking caissons. Factors which have led to success or failure are reviewed and evaluated, and recommendations for future investigation, design and construction activities are presented. Cost data for five recent projects are reviewed and compared to the cost of shaft installation by other means.

Jan 1, 1997

By M. M. Rajkovich, L. Adams, J. J. Zaluski, S. Gardner

In 1998, Kentuckians for the Commonwealth filed an Administrative Petition with the Kentucky Natural Resources and Environmental Protection Cabinet to designate 8,903 +/- hectares (22,000 +/- acres) on Black Mountain, which contains the state’s highest point, as unsuitable for mining. A fast track legislative process was triggered which could have "taken"100 million tons of coal reserves or, in the alternative, imposed severe restrictions on mining. Even with all parties represented by reasonable individuals, this process can be extremely cumbersome and expensive. The legal and technical preparation for this unusual hearing process as well as issues and strategies of the negotiated resolution are reviewed.

Jan 1, 2000

By B. Cavender

Mining managers trying to rapidly reduce production costs tend to implement a traditional set of top-down managerial practices: layoffs of employees, renegotiation of supplier contracts, cancellation of employee training, restrictions on travel, reductions in office supplies, and so forth. While these practices do reduce costs, the benefit is often limited in both magnitude and duration, and the workforce is usually left demoralized. Successful cost-cutters take a different approach. They make the continuous reduction of costs a priority for all members of the organization, whether managers or workers. The culture of these firms emphasizes the commitment, voluntarily given, of individuals and work groups to this goal. Cost cutting practices often reject all of the traditional methods mentioned above, but are far more numerous, innovative, and successful. This culture of cost reduction is the result of a set of leadership competencies that establish direction for the organization, align the organization’s various constituencies with this direction, and motivate and inspire the organization. Dramatic cost reduction then becomes a routine task rather than a heroic achievement.

Jan 1, 2000

By Reul A. Dejú

The mineral olivine has been the subject of continued research by various authors. Paik (1967) conducted infrared and flotation studies of the adsorption of sodium alkyl benzene sulfonates on olivine. These studies are of interest from two points of view. First, in the metallurgical field it is of interest to understand the mechanism of silicate flotation using sulfonate collectors and second to a hydrologist studying the pollution of surface or subsurface waters it is of interest to study the reactions taking place when water plus sulfonates encounter a porous (silicate) medium. On the basis of Paik's study he was able to postulate a possible mechanism for the attachment of RSO3 (sulfonate radical) to the olivine surface. Parks (1969) has been studying the important influence of the structure of a silicate such as olivine on its dissolution mechanism and its related surface charge. Also Luce, a student of Parks (1964, 1965) has been studying the kinetics of dissolution of olivine using the techniques of direct solution analysis and infrared analysis. Certainly a classic in the study of silicate dissolution is the work of Murata (1940) on the reaction of orthosilicates (olivine in particular) with strong acid solutions. Many authors (Dejú and Bhappu, 1966. 1967. 1968, Dejú, 1969; Rhoades and Krueger. 1968, and Faust and blunter, 1967) have reported studies of the behavior of silicates immersed in water (especially orthosilicates) and have found that there is an exchange of cations from the silicate surface for H+ from the water. Studies by Dejú and Bhappu have also included the system olivine-water-amine.

Jan 1, 1971

By D. L. Kiser

Conventional and advanced coal preparation technologies were investigated through both a literature search and through direct contact with investigators and developers. In addition to a brief description of each process, performance characteristics including feedstock type, ash and sulfur reduction, thermal energy recovery and cost are provided in a tabular form. Seven of the most commonly utilized conventional coal preparation processes, including those respectively accepting coarse, intermediate and fine coal feed, were reviewed. It was found that certain properly implemented and well maintained conventional processes were capable of better than 75 percent ash removal while recovering 90 percent or more of the inherent thermal energy. Almost 50 advanced coal preparation processes were investigated based on biological, chemical and physical principles. Physical processes investigated included cycloning, homogeneous heavy media, electrostatic, high gradient magnetic, flotation and selective coalescence. Using pulverized coal as a feedstock, some of these processes are respectively reported to be capable of removing better than 95 percent ash. 95 percent pyritic sulfur, and 50 percent organic sulfur while incurring energy losses of less than 5 percent.

Jan 1, 1986

The Virginia Center for Coal and Energy Research has been developing models of wireless signal propagation in underground coal mines since 2007. The current mine propagation modeling software, named COMMS, is able to locate potential broadcast points for underground wireless mesh systems and estimate their coverage. COMMS utilizes programmed routines to calculate necessary values to both quantitatively and qualitatively solve and analyze predicted coverage areas. The program approximates the spatial relationships that are encountered, such as ventilation regulators, belts and other obstructions. Using this model for propagation allows the optimal communications node locations to be calculated, by using lessons learned from current installations and experience with the new technology. In addition, the optimization can be calculated by checking all possible combinations of broadcast locations. This paper compares these optimization calculation methods. The ability to solve a mine?s communication network provides a pre-installation mine network design map, creates coverage maps of the mine and allows planning for future communication activities

Jan 1, 2011

By Susana Bolhão Muiños, José Hipólito Monteiro, Martin Frank, James R. Hein, Henrique Garcia Pereira, Fátima Abrantes, Tracey Conrad, Luís Gaspar

In spite of all the work that has already been done on ferromanganese deposits, studies on the Atlantic Ocean occurrences are still in their infancy and there is a clear need for investigations concerning the origin, distribution, and resource potential assessment of these deposits. Nevertheless, studies already carried out on northeast Atlantic seamounts indicate the general presence of ferromanganese deposits of hydrogenetic origin, i.e. deposits formed by direct precipitation of colloidal, hydrated metal oxides that are scavenged from the water column on hard-rock substrates. The hydrogenetic precipitation promotes the enrichment of ferromanganese crusts in many trace metals, most of which are of economic interest, such as Co, Ni, Te, rare earth elements, and platinum-group elements and thus ferromanganese crusts are considered an important metal resource.

Sep 1, 2014

By D. J. Turk

Stillwater Mining Company’s, Nye Operation has been producing PGM concentrate since 1987.Several expansions have allowed for increasing capacity from the initial rate of 500 tons per day, to its present capacity of 3,000 tons per day. The expansions were performed with minimal impact upon production and maximum utilization of the existing equipment. The latest expansion incorporates a 6’ X 18’ SAG mill, 13’ X 20’ Ball mill, pebble crusher, rougher flotation cells, 1250 Hp tertiary grinding mill, middling and scavenger flotation cells, and cleaner column flotation cells. This paper will describe the concentrator flow sheet, and controls for improved concentrator performance.

Jan 1, 2000

By W. B. Greer, J. J. K. Daemen

Introduction The performance of seals in boreholes, shafts and tunnels is an important concern in mine safety, in the control of effluents from operating and abandoned mines and in the underground containment of hazardous wastes (Einarson and Abel, 1990; Mining Waste Study, 1988). Despite the clear need for effective seals, few documented test results are available concerning the performance of in situ seals. Some evidence indicates that horizontal or near-horizontal holes are especially difficult to seal properly (Kelsall et al., 1982). This research involved the installation, extensive hydraulic testing, removal and post-test examination of a 10-cm-long x 10-cm-diam cement grout seal in a near-horizontal borehole in limestone. The work was performed in an underground mine on Marble Peak in the Santa Catalina Mountains, AZ. A test hole was diamond cored in the recrystallized limestone of the Escabrosa formation. The hole is 33.24 m long, 10 cm in diam, and dips at 10.4°. The hole extends between two drifts and thus is accessible from both ends. Seal installation Surveys to assist in selecting the interval to seal consisted of core logging, video logging and constant-head injection tests using a straddle-packer unit. The location selected, 3 m from the lower end of the hole, had low hydraulic conductivity (3 x 10-10 to 3 x 10-9 cm/sec) and was free of significant fractures. The grout used, an expansive Class A cement, was provided by Dowell-Schlumberger, Tulsa, OK. A grout mass about 1.5 m in length was installed, with a dump bailer, above a temporary mechanical plug. Groundwater in the hole, if any, was minimal during placement. After 13 days of curing, the grout mass was partially drilled out from both ends, leaving a seal 10 cm long. Water distribution in rock mass The distribution of water and fluid pressure in the rock mass near the seal appears to be complex. The generally dry condition of the borehole and rock mass suggests that the rock mass near the seal was unsaturated prior to the injection tests of this research. The injection tests presumably created an expanding saturated zone around the seal. However, anomalously high fluid pressures, consistently recorded by one of two piezometers installed near the seal, suggest connection to a source of significant natural hydraulic head. Comparable head variations for closely spaced piezometers have been reported by others (Sowers, 1976). [ ] Seal testing The seal was tested for 3.5 years, using steady constant-head, tracer travel-time, dye-injection, head-buildup and transient constant-head tests. These tests are fully described in Greer and Daemen, 1991. In the head-buildup test, transient flow occurs through the seal (and rock mass) to a closed, water-filled interval of the borehole adjacent to the seal. The test consists of monitoring the rise in head in the closed interval until steady conditions are approached. The test may be analyzed in terms of a one dimensional analytical model to obtain the effective hydraulic conductivity (Ks) and specific storage (Sss) of the seal. Analysis in terms of an axisymmetric three-dimensional numerical model may yield properties of both the seal and rock mass.

Jan 1, 1993

By C. J. Burkhalter, H. Andrade, T. C. A. Gardner, J. P. Campbell

During the 1990’s several copper heap leach facilities treating crushed and agglomerated oxide and sulfide ore were constructed in South America. The majority of these facilities have been in operation for at least three years, during which time the operators have been able to monitor the performance of the heaps. The basis for the paper is a compilation of these operators’ experiences, leading to a discussion of the lessons learned over the past decade. Several key geotechnical issues are examined, focusing upon the integrity of the ore, drainage material and pipe network, along with the success of any inter-lift liners.

Jan 1, 2002

By Ian Sheppard, Kugan Kuganathan

The Mount Isa Rocky Paste Fill (RPF) was one of the five fill options investigated for the Enterprise Mine filling between June 1996 and September 1996. Co-disposal of deslimed cemented tailings (CHF) and suitably graded rockfill (RF) in certain ratios produced the rocky paste fill. The RPF behaved like a cohesive paste with very high proportion of rockfill in the mix. Several large-scale mixing trials and drop tests proved that the rocky pastefill results in a homogeneous fill mass after placement. Segregation of RF was a common problem with MIM's traditional cemented rock fill (CRF), which is a combination of CHF and RF. The segregation was eliminated and a non-segregating paste like fill was created by optimising the particle size distribution of RF, and combining the RF and the CHF in optimum ratios. In rocky pastefill, the excess water in the cemented deslimed tailings slurry is taken up by the rockfill as the surface moisture on the rockfill particles and also as pore water between the particles. This results in thickening of the CHF, and the resultant mix is a non-segregating cohesive paste, which can easily spread to any horizontal distance inside a stope at a very low surface angle. The rocky pastefill releases no free water and relatively more pervious than the standard CHF due to rockfill component. With an average cement addition of 1.5 to 2% the rocky pastefill can develop higher strengths over 1Mpa. The rocky paste fill is applicable in many situations and can accommodate a variety of coarser materials that would be available in different mine sites. This paper present the research work and the experience associated with the rocky paste fill, and gives clear design principles for any potential users.

Jan 1, 2001

By Zoltan F. Oszter

The frictional resistance to motion of a belt conveyor has always been a subject of intensive studies and research by engineers throughout the years. Numerous informations have been developed by analysing series of field tests on belt conveyors of different characteristics and carrying different materials at various capacities. Within certain limits of weight per unit length and tension, the theoretical considerations and the analysis of the field tests, both in the US and abroad, resulted in the development of similar formulas. In general these formulas are safe to use up to the following limits:

Jan 1, 1977