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By Mark Van Dyke, Ted Klemetti, Joe Wickline

"The identification and mitigation of adverse geologic conditions are critical to the safety and productivity of underground coal mining operations. To anticipate and mitigate adverse geologic conditions, a formal method to evaluate geotechnical factors must be established. Each mine is unique and has its own separate approach for defining what an adverse geological condition consists of. The collection of geologic data is a first critical step to creating a geological database to map these hazards efficiently and effectively. Many considerations must be taken into account, such as lithology of immediate roof and floor strata, seam height, gas and oil wells, faults, depressions in the mine floor (water) and increases in floor elevation (gas), overburden, streams and horizontal stress directions, amongst many other factors.Once geologic data is collected, it can be refined and integrated into a database that can be used to develop maps showing the trend, orientation, and extent of the adverse geological conditions. This information, delivered in a timely manner, allows mining personnel to be proactive in mine planning and support implementations, ultimately reducing the impacts of these features. This paper covers geologic exploratory methods, data organization, and the value of collecting and interpreting geologic information in coal mines to enhance safety and production.The implementation of the methods described above have been proven effective in predicting and mitigating adverse geologic conditions in underground coal mining. Consistent re-evaluation of data collection methods, geologic interpretations, mapping procedures, and communication techniques ensures continuous improvement in the accuracy of predictions and mitigation of adverse geologic conditions. Providing a concise record of the work previously done to track geologic conditions at a mine will allow for the smoothest transition during employee turnover and transitions. With refinements and standardization of data collection methods, such as those described in this paper, along with improvement in technology, the evaluation of adverse geologic conditions will evolve and continue to improve the safety and productivity of underground coal mining."

Jan 1, 2019

By Keith A. Heasley, Lee W. Saperstein

This paper investigates the use of backfill zones and yielding pillars for subsidence control. The investigation begins by choosing an appropriate subsidence predictive technique to simulate the proposed subsidence-control schemes. Two case studies are performed in order to delineate the accuracy and utlility of the chosen predictive technique and then the results of these case studies are used to establish appropriate sets of regional site parameters. Next, a detailed analysis of the major variables affecting the outcome of the subsidence-control simulations is conducted and graphical displays of the exact sensitivity of the surface subsidence to these variables are given. Finally, alterations to the surface subsidence that are expected from using two major subsidence-control techniques are presented. The first technique to be assessed is a backfilled pillar centered longitudinally in a panel. With this arrangement, a minimal amount of backfill material can produce substantial decreases in vertical displacements. The second technique to be assessed is the use of yielding gate pillars to reduce the sinuosity of the transverse subsidence over adjacent panels. With proper design, this technique can greatly curtail surface strains and help minimize remedial drainage control.

Jan 1, 1986

By S. Kittel, P. Galleguillos, H. E. Urtubia

The rougher flotation at Escondida consists of 80 cells of 100 m3 each, with injected air. Escondida has developed a system of automatic control of the rougher flotation using video cameras, which have been operating since 1997 for remote monitoring and manual control. Since 1999, an image processing software and a group of rules have allowed implementation of an expert system. To date, the expert system controls the superficial speed of each cell by adjusting the air flow and the froth depth of the flotation bank. Preliminary tests of the expert control on two of the eight rows gave 1.2% higher rougher recovery at a 92% degree of confidence. The proven benefits are already sufficient to move towards a complete plant implementation.

Jan 1, 2001

Membrane technology has been available for over 36 years, but has been used sparingly in the general mining industry. However, recent developments in polymer chemistry, spiral wound element construction, pretreatment equipment and techniques and an expanded understanding of membrane fouling and cleaning techniques have dramatically improved the reliability and robustness of membrane based systems in the mining industry. Harrison Western has expanded the use of this “new” technology to enhance the use of membrane technologies to separate metals from large volume heap leach mining solutions containing copper, zinc, and iron, gold or silver. Moreover, membrane technologies are ideally suited to fractionations that add value to processing fluids from refineries like separating metals from acids or concentrating acids and producing high quality process fluids. Finally, wastewater from Acid Mine Drainage (AMD) or, as in the case of the Newmont Yanacocha Mine in Peru, the treatment of excess barren leach solution created during the rainy season, can be cost effectively processed to meet World Bank Standards for surface discharge. Polymeric membranes, specifically thin-film composites, have been developed that will purify, fractionate or concentrate gold, silver, copper, zinc or nickel. Recent applications have been developed for spiral wound modules that operate across the pH spectrum from 0 to 14. Systems using membranes have been constructed that operate on feed streams from 140° C to 300 centipoise. Opportunities exist to apply membrane technology to concentrate gold, silver, copper, zinc or nickel using thin film composite membranes. Engineered membrane types can operate across the spectrum from low pH (<2) acid applications to high pH > 10 cyanide applications. Incorporating HW EMS™ membrane technologies into current mining operations could allow one to increase production because the membrane technology would be used to pre-concentrate heap leach solutions, and therefore, increase utilization of existing extraction and refinery capabilities.

Jan 1, 2007

By G. J. Olson

This paper describes the microbiology basics underlying heap and tank biooxidation of metal sulfide ores and concentrates. The primary organisms are identified and described along with the reactions they catalyze and their growth requirements. Also described is the interaction between ore leaching bacteria and the leaching environment in terms of solution chemistry, temperature, and mineral precipitation. Specific factors and agents that stimulate or inhibit growth and activity of ore bioleaching will be identified. Some of these factors are organism-specific and others are generic for microorganisms that grow under acidic conditions. Current knowledge of the limits of bioleaching in terms of dissolved ions in leach solutions, pH, and temperature will be summarized.

Jan 1, 2003

By Yi Luo, Jian Yang, Hua Jiang

Surface subsidence events induced by underground longwall coal mining operations can cause various disturbances to surface structures ranging from integrity and stability to functionality problems. Highway bridges, as a kind of special road construction that can only tolerate smaller movements and deformations than road pavements, are particularly susceptible to severe influence caused by subsidence-induced ground movements and deformations. However, based on accurate subsidence prediction and correct influence assessments, efficient and effective mitigation and remediation measures can be designed and implemented to ensure the continuous service of bridges, safety of the travelers and smooth mining operations. In this paper, based on the predicted final and dynamic surface movements and deformations, the techniques to assess subsidence influence on the integrity, stability and functionality of bridge structures (e.g., decks, beams, abutments, etc.) are presented. A number of mitigation measures to protect the bridge structures are recommended along with an actual application case.

By Dan Martz, Bill Moler, David Young, Wally Chen, Matthew Crow, Steve Norris, Tolga Togan

Two 610 m (2000 ft) long tunnels were driven through water bearing silts, sands and clays beneath the Sacramento River using a 4.59 m (15.1 ft) diameter Earth Pressure Balance Tunnel Boring Machine (EPBM). Four sheet pile shored shafts were sunk with and without dewatering. The pre-cast concrete segmentally lined and grouted tunnels were driven down at 6% grades beneath the river flood protection levees, buildings, roads, a railroad and adjacent to a Freeway Viaduct. Details of the schedule, cost, shaft construction, TBM, tunnel construction, and installation methodology for the twin1.676 m (66 in) steel force main pipes and environmental constraints are provided.

Jan 1, 2007

By The SME Sustainable Development Committee

The evolution of sustainable development in mining is recognized as a key contributor to sustainable development (SD), which is defined as the ability of current generations to meet their needs without compromising the ability of future generations to meet their own needs (Brundtland, 1987). This includes, in equal parts, social, economic and environmental impacts ? triple bottom line (Munashinge and Shearer, 1995). Alternately, sustainability has been defined in relation to social, natural, human, physical and financial capital. Our way of life relies significantly on the materials provided by mining, while mining activity affects the triple bottom-line or the five capitals. The mining community and its professionals have come to realize the importance of engaging all stakeholders in the discussion on sustainability. SME, as the leading professional mining organization, has been involved in these discussions. The society has various initiatives in sustainable development for members and stakeholders. The objective of this article is to: provide historical context for current trends in mining and SD and share SME sustainability initiatives ? their goals and rationales ? with the broader mining community. This article is timely because the past year saw two landmark forums on sustainable development: Rio+20 ? the 20th meeting of the United Nations Conference on Sustainable Development, and MMSD +10, the Mining, Minerals and Sustainable Development project 10 years on. Furthermore, this year marks the 10th anniversary of the Milos Declaration on the minerals professional?s responsibilities in achieving sustainable development, forums in which SME was involved.

May 1, 2013

By Sumit Kumar Hota, Asadi Srinivasa Reddy, Ashok Kumar, Ashish Agrawal, Surajit Sinha, Chandra Sekhar, Tanay Ray

In the current operational facility, due to the absence of pellet pot facility, a novel technique is developed wherein the pellets with different chemistries prepared in the laboratory are fired in an induration machine by placing them inside the Inconel baskets. In the present work, an attempt is made to optimize the pellet chemistry by developing 2 different flux pellets, viz., low basicity (B2: CaO/ SiO2 = 0.3) pellets and high basicity (B2 = 0.9) pellets, and further the effects of basicity on pellet properties, viz., cold compressive strength, porosity, swelling index, reducibility index, and softening and melting temperature, are studied. It has been found through the multiple operational trials that increasing the basicity of pellets from 0.3 to 0.9 results into improving the pellet strength, reducibility and softening and melting characteristics. Moreover, it is observed that the swelling index of pellets is reduced by adding 2% MgO to both low and high basicity pellets that could be attributed to the formation of high melting point slag in pellets. The operational trial has resulted into producing pellets that exhibit a combination of desired mechanical strength, improved swelling, and reducibility index and possess better softening–melting behavior among all the chemistries studied.

May 24, 2022

By R. L. Brown

The Buchans mining district is located roughly at the center of the island of Newfoundland and contains some 18 separate mineral deposits. The first of these deposits was discovered in 1905, the latest discovery having been made in 1979. To the present (1983), some 16 Mt (17.7 million st) grading 1.33% Cu, 7.5% Pb, 14.5% Zn, 115 g/ t (3.7 oz per ton) Ag, and 1.4 g/t (0.04 oz per ton) Au have been mined. Mining operations are now largely terminated, but a few hundred thousand tons of economically marginal reserves may be mined in a salvage operation. The Geological Association of Canada Special Paper No. 22, "The Buchans Orebodies, 50 years of Mining and Exploration," contains papers which describe the history, geology, and the application of evolving geological concepts in exploration. Papers by Neary, Swanson, and Thurlow and Swanson in that volume are topical to the present discussion. Successful exploration techniques at Buchans included physical prospecting, utilization of the state-of-the-art geophysical techniques, saturation diamond drilling which was made possible by the high gross value of the existing ore, and, since 1955, diamond drilling directed by fairly well understood geological parameters. The record of discovery started in 1905 when the Buchans River deposit was found by Matty Mitchell, a prospector employed by the Anglo- Newfoundland Development Co., a British company which owned mineral rights over a very large area in the Red Indian Lake-Exploits River drainage system.

Jan 1, 1991

By William R. Yernberg

A conference on coalbed and coal mine methane was held March 27 and 28, 2000, in Denver, CO. The conference, organized by the Strategic Resource Institute, was attended by leaders in the coal mining and gas energy industry. The conference focused on the recovery of methane from coal beds as an energy resource and the removal and utilization of coal-mine methane (CMM) related to underground coal mining. The two-day conference discussed methane resources around the world, methods of recovery, methane markets, underground coal mining, health and safety issues and environmental issues related to methane. The consensus among the presenters is that the future looks promising for coal bed methane (CBM) and CMM.

Jan 1, 2000

By Tianzu Yang, Weifeng Liu, Lin Chen, BOYI XIE, DUCHAO ZHANG, HUI XIAO

In this study, the oxygen-rich bath smelting process of copper dross was simulated using Factsage software. It was found that the two-step simulation results agreed better with the industrial data, especially in the speiss. Bismuth (Bi), lead (Pb), antimony (Sb), arsenic (As) and copper (Cu) contents in the speiss by two-step simulation differed from the industrial data by 0.6, 0.8, 2.6, 7.2 and 8.6 weight percent, respectively. The two-step simulation results indicate that the speiss partitioning of Sb, As and Cu increased from 60.1, 32.3 and 27.5 percent to 81.6, 67.8 and 47.2 percent, respectively, with the smelting temperature increasing from 1,050 to 1,250 °C, while the metal partitioning of Sb and Cu increased from 0 and 2.7 percent to 15.2 and 13.3 percent, respectively, with the separation temperature increasing from 400 to 700 °C.

By Y. FUJII, E. CHANDA, J. KODAMA, D. FUKUDA, M. NISHIHARA, Y. NAKAYAMA, P. SINKALA

For over 40 years, Mufulira underground copper mine has been recording incidents of rockburst. Laboratory tests and numerical analyses were carried out to understand the rockburst mechanism at the Mufulira mine. Rockburst did not occur in the chain pillars or at the mining face, but mainly in the mining drives along diminishing pillars or ahead of the mining face. RQD suggested that the rock mass in the rockburst areas was relatively intact. Laboratory tests confirmed that the rock at Mufulira mine is very strong and brittle. Elastic stress analyses for the rockburst sites by 3D displacement discontinuity method (DDM) indicated very high stress in the chain pillars and low-stress concentration at the sites of rockburst during the initial mining stages. However, there was no apparent positive correlation between the elastically calculated normal stress values and the occurrences of rockbursts. The 2D elastic FEM analysis was conducted under the concentrated stress by DDM and indicated that some stress increase with face advance for the rockburst in the vicinity of the mining face. However, stress severity indicated almost no increase, and the rockbursts cannot be explained as an instantaneous rock mass failure due to stress increase by mining. Therefore, a creep damage model was proposed to clarify the mechanism of the rockbursts. Cumulative rock damage was evaluated for the edge elements of each sidewall of the mining drives, based on the normal stresses by 3D DDM. The rockburst occurrences were well hindcasted. A method to estimate the volume of the rockburst source was proposed, and a likely result was obtained.

Aug 12, 2022

By Richard A. Bideaux

With both unit costs per meter and average depth of drilling constantly increasing, there is a strong incentive to maximize the information acquired from drill holes, and then to make this information accessible to the geological staff. The larger the drilling project, the more advantageous computerization of data is over manual methods. The conversion to computer-readable form and the verification of large amounts of drill-hole data can be a substantial data processing task, but once accomplished, the benefits in increased accuracy and speed of interpretation will compensate for the time and effort spent in the work. For an exploration project progressing towards a preliminary feasibility study, about half of both the time and costs for all computer work of the entire feasibility study are devoted to drill-hole data base organization, and maintenance. Once drill-hole results are quantified and verified to be correct, they are immediately accessible and are not subject to further transcription or reinterpretation of errors. To obtain maximum benefits from computer utilization in this area, the drill-hole data base should be set up along with availability of the first data. For some companies, this may initially comprise a large number of purely speculative drill holes on a spacing of perhaps 1 or 2 km. Although few of these drill holes may encounter economic material, thought should be given, at this time, to the variables which will be logged when such material is found. In this way, it should be possible to set up a consistent format into which all future drill-hole information will readily be accommodated. This format may even be carried over into the data base requirements for an operating property.

Jan 1, 1979

By H. Lowers, P. Hageman, S. Diehl, D. Fey

Understanding relationships between mineralogy, texture, microstructural features, and element distribution and residence in minerals, is critical for accurate modeling of mineral weathering in waste-rock piles. The morphology of minerals and deformation structures, such as veins and faults, are important factors that control: (1) fluid access to the mineral surface to initiate dissolution, (2) the distribution of trace elements, and (3) formation of secondary minerals. We characterized the mineralogy, textures, and chemical properties of waste-rock material at three sites at scales ranging from outcrop to micrometer scale. A comprehensive hand-sample to thin-section scale methodology utilizing light microscopy, scanning electron microscopy, electron microprobe, and laser ablation ICP-MS was used to thoroughly characterize the waste-rock material.

Jan 1, 2007

By A. Wahab Khair, John G. Oldsen, John C. Stankus, Song Guo

During the last several years, implementation of trusses, in lieu of wood cribs, has been successful for supplemental tailgate support in the Pittsburgh seam. This paper reviews, the truss support system provided by the new high strength 0.6" tensioned cable truss, which is now also being used in cribless tailgates. Cable loading and roof deformation were monitored to evaluate roof and floor performance. The test results indicate that the cable truss system successfully controlled the roof and floor during the first and second panel extraction. This paper will describe the advantages of cable trusses and their load transfer mechanism as well as mine evaluation.

Feb 24, 1997

By Desiree Willis

One of New York City?s largest subway projects is under way 43 m (140 ft) beneath the surface of downtown Manhattan. The East Side Access project, more than 30 years in the making, was halted after a partial excavation in the 1970s due to a lack of funding. The project, once dubbed the ?Tunnel to Nowhere,? has been revitalized into a groundbreaking subway line that includes unique tunnel boring machines (TBM), construction methods and muck removal systems. Project overview The East Side Access project involves construction of a new 6.7-km (4.2-mile) subway line needed to relieve heavy traffic congestion between the boroughs of Queens and Manhattan. The line will serve approximately 160,000 commuters daily between Grand Central and Sunnyside rail stations. Manhattan and Queens will be connected under the East River by the 63rd Street tunnel, a submersed double-decker tube. The submersed tube consists of reinforced concrete sections barged in place on the riverbed. The tube contains operational subway lines on the top deck, while the bottom deck (the ?Tunnel to Nowhere?) will become operational when the East Side Access project is completed in 2013.

Jan 1, 2008

By G. Brackebusch, S. J. Jung

Backfilling techniques are widely used in large-scale underground mines. Massive pillars, which have been left in place for stability, limit mining activity. Backfilling allows safe recovery of the ore remaining in pillars and assures long term stability. In deep mines expected high stress can be relieved with the backfill. Initially, waste rock was used to fill the openings with mixed results. The need to improve safety and reduce costs has prompted the industry to investigate alternatives. Hydraulic filling with Portland cement added has shown considerable promise, but little has been done to define the parameters of design effective system. The purpose of this study is to determine the relationship between backfill and mining components that can be used to effectively design a best-case hydraulic backfill.

Jan 1, 2000

By Andrew E. Nevin

The government of India convened a precedent-setting meeting in New Delhi on Nov. 12, 2001.The meeting brought together regulators and the mining industry in an attempt to fix the industry’s mine development problems in that country. More than 150people attended the all-day session. Ram Vilas Paswan, Minister of Coal and Mines, chaired the meeting. Ravi Shankar Prasad, Minister of State for Coal and Mines, was also present. The secretary of the Department of Mines and the Joint Secretaries and Additional Secretary also participated. The Department of Mines’ mandate is for economic growth: to get new mine development going and to make investment in mining attractive for both domestic and foreign-owned companies.

Jan 1, 2002

By G. T. Austin

Every year the United States consumes millions of dollars worth of abrasive materials as blasting media. Entrained in either a gas or liquid stream or propelled by paddles or wheels, they are directed onto the surface of another material to modify that surface. The modifications to impacted surfaces include cleaning, cutting, deburring, etching, finishing, and peening. Blasting media can be either organic or mineral abrasive materials. Information and data presented are for only a portion of the mineral abrasives, they are; fused aluminum oxide, coal slag, copper slag, garnet, metallic shot and grit, nickel slag, olivine, silica sand, silicon carbide, and staurolite.

Jan 1, 1994