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By Richard Short

Shallow rainfall-induced landslides in residual and colluvial hillslopes and steep embankments are a common occurrence in many settings [1, 2, 3]. While occasionally posing a threat to property and life-safety, they more often present an ongoing maintenance problem and can lead to the initiation of larger failures. Typically, these slides consist of 2 to 4-foot thick translational movements of silty and clayey soils down slope through the reduction of strength from increases in pore water pressures. Direct surficial infiltration and indirect groundwater seepage are the normative triggers for failure. In the residential community of Blackhawk, California, located east of the San Francisco Bay, these types of landslides are a common occurrence (Figure 1). However, shallow landslides have also been a repetitive and constant problem along many state highways where steep embankments have been constructed in close proximity to busy thoroughfares. Given the real threat to property values in residential and commercial settings and the constant maintenance problem posed to lifeline structures such as utilities, roadways, and pipelines, new methods to deal with these landslides are needed.

Jan 1, 2007

Vein swarms in metamorphic terranes such as the Otago Schist Belt, New Zealand provide evidence of past hydrothermal flow systems leading to fault initiation and reactivation. A major episode of hydrofracturing and fluid redistribution occurred during early Cretaceous exhumation of the schist belt. As a result, presently exposed lower greenschist facies greyschists in NW Otago are pervaded by abundant quartz-filled hydraulic extension fractures with associated normal faults hosting quartz¦scheelite¦gold mineralisation. Once the effects of Cenozoic folding have been removed, a regional subhorizontal schist foliation contains an aligned array of subvertical hydrofractures striking NNW, striking parallel to a set of low-slip conjugate normal faults; the array extends over an area >1500 km2 and over a depth interval >5 km. The hydrofracture array comprises a mesh of interlinked extensional-shear and pure extension veins. These veins show mutually cross-cutting relations. Extensional hydrofracturing apparently preceded the development of major throughgoing normal faults. Low-displacement normal faults are infilled with laminated quartz (¦ scheelite) veins (

Jan 1, 2002

Abbott, Argyle Campbell 1209 Sherwin Ave., Chicago, Ill. Almstrom, Adne A., Student, Met. Engrg., Washington State College Pullman, Wash. Ankudinoff, N., School of Mines, Univ. of Utah Salt Lake Cite, Utah. Apter, Robert F., Student, McGill Univ Montreal, Que., Canada. Bailey, Donald G 798 Kensington Rd., Los Angeles, Cal. Baker, Kenneth B., Met., Aluminum Co. of America Pittsburgh, Pa. Barger, Thomas, Student, Univ. of North Dakota Grand Forks, N. D. Bartholomees, Geo. C Box 304, Bonne Terre, Mo. Bates, Walter, Student, Univ. of Utah, School of Mines Salt Lake Cite, Utah. Bobb, Russell V 16 College Ave., Houghton, Mich. Boswell, John C., Stripping Asst., Fairbanks Exploration Co Fairbanks, Alaska. Brandenburg, E. C., Student, Univ. of Kentucky 112 Church St., Lexington, Ky. Brannen, John, Chemist, Assay Office, Consolidated Min. & Smelt. Co. of Canada, Ltd., Tadanac, B. C., Canada. Brooker, Edgar, Jr., Student, Ferrous Met., Stanford Univ., Stanford University, Cal. Brooking, Leslie E 738 Lakoma, Norman, Okla. Clark, Martin Lester, Student, Missouri School of Mines Rolla, Mo. Collins, Edward D., Jr Box 1597, Ribbing, Minn. Comeau, Faye Bernard, Student, New Mexico State School of Mines Socorro, N. M. Conder, Henry S., Student, Pet. Engrg., College of Min., Univ. of California, Berkeley, Cal. Cotton, John Francis, Metallographist, Stealton Plant, Bethlehem Steel Corp., Steelton. Pa. Dahlgren, Elmer George, Student, Univ. of Wisconsin, Tripp Hall, Madison, Wis. Dale, James L., Student, Colorado School of Mines Golden, Colo. Dashti, Mirza Abdullah Khan, Graduate Student, Columbia School of Mines, Engrg. Chemistry, New York, N. Y. DeHuff, Gilbert L., Jr., Student, Lehigh Univ Bethlehem, Pa. de Romana, Enrique P., Jr. Engr Casilla 22, Arequipa, Peru. Oresbach, Charles Howard, Geol., Gulf Production Co Box 1428, Amarillo, Tex. Evens, Howard G., Student, Michigan College of Min. & Tech Houghton. Mich. Fassler, Glen Emerson Rodman, Inspiration, Ariz. Feight, Charles Donald, Foreman, Clairton By-Product Coke Wks., Carnegie Steel Co., 319 5th St., Wilson, Pa. Floe, Carl F., Student, State College of Washington Pullman, Wash. Fuentes, Vicente, Student, Pet. Engrg., Univ. of Oklahoma, School of Mines, Norman, Okla. Fuhrman, Carl F., Student, New Mexico School of Mines Socorro, N. M. Goergen, Gerald G., Cerro de Pasco Copper Corp Casapalca, Peru. Grove, Hubert A., Training Course, U. S. Aluminum Co New Kensington, Pa. Gastetter, Robert E 1010 N. Cherry Ave., Tucson, Ariz. Halbouty, M. T., Student, Texas Agriculturcl & Mech. College, Box 254, Faculty Exchange, College Station, Tex. Halfast, Edgar 710 E. Okmulgee Ave., Muskogee, Okla. Hall, Robert Lee 121 58th St., Niagara Falls, N. Y. Hanson, Rolf H., Student, Colorado School of Mines Golden, Colo. Hillyer. Shaler G., Student, New Mexico School of Mines Socorro, N. M. Hoertel, Frederick W., Met., R. W. Hunt Co., Engrs St. Louis, Mo. Holtz, Henry G., Student, Ohio State Univ Columbus, Ohio. Hon, Richard J Box 721, Miami, Ariz. Huffman, James O'Neil, Student, College of Min., Univ. of California Berkeley, Cal.

Jan 1, 1929

Objective To accurately measure very low air velocities (0-100 ft/min) in U.S. large-opening underground metal/nonmetal mines. Background Hundreds of metal/nonmetal underground mines operate throughout the United States. They extract commercial products from deposits such as limestone, salt, and gypsum. Mining generates a wide variety of gases and dusts, such as silica, diesel exhaust, radon, blasting byproducts, and perhaps even methane. If these substances become airborne, they can adversely affect the health and safety of underground workers. Many metal/nonmetal mines have large cross-sectional airways that could be 60 times larger than an average underground coal mine entry. These large airways require adequate volumes of fresh air to dilute, make harmless, and exhaust the toxic and, at times, explosive byproducts. However, in some underground mine sections, air movement is barely perceptible. The technology of measuring very low air velocities will become increasingly more important for operators of large-opening stone mines in order to monitor miner exposure to diesel particulate matter. Conventional anemometers (e.g., vane) are capable of accurately measuring air velocities only above 100 ft/min. Thus, it was necessary to investigate other anemometry technology to detect low air velocities in the range of 0-100 ft/min. Two different portable ultrasonic anemometers were tested. Actual testing was done in an underground limestone mine with openings about 51 ft wide by 29 ft high. Ultrasonic Anemometers Vane-type anemometers are commonly used by engineering personnel throughout the underground coal mine industry. They work well in measuring air velocities >100 ft/min. However, a separate technology, e.g., portable ultrasonics, is needed to measure air velocities much below 100 ft/min at various places within the large mine opening. Laser-doppler technology was also considered for this application, but was ruled out because of its high cost and other technical limitations. With no moving parts, the portable ultrasonic anemometers are claimed to be accurate down to about 1or 2 ft/min. The first type of ultrasonic anemometer that was examined underground is manufactured by Gill Instruments Ltd., Hampshire, U.K. The U.S. distributor is IN USA, Needham, MA. The Gill Instruments Solent Volometer (figure 1) is a battery-powered, single-axis anemometer meant for measuring low to medium air flows up to1,999 ft/min. It uses the ultrasonic "time of flight" principle where pulses of high-frequency sound are transmitted along the air flow path and the time taken to reach the receiver is measured. The faster the air speed, the quicker the pulses reach the receiver. The second ultrasonic anemometer that was examined under-ground is manufactured by Airflow Developments Ltd., Buckinghamshire, U.K. The U.S. distributor is Airflow Technical Products, Inc., Andover, NJ. The Anemosonic UA-6 (figure 2) is a battery-powered, handheld instrument with digital display. It measures air velocity (0 to 9,999 ft/min) or volume flow, flow turbulence intensity, and air temperature. Neither device is considered to be intrinsically safe for use in underground gassy coal mines. A comparison of salient specifications of both instruments is shown in table 1. The total suspended weight includes the instrument (Gill) or instrument probe (Airflow) plus about 35 ft of connecting cable attached to the pole. This combination of instrument plus cable length allows two operators to measure air velocities up to about 30 ft above the mine floor. Figures 1 and 2 show how each unit would be attached to an extensible, graduated fiberglass rod in order to position the sensor probe at a certain spatial point (centroid of the quadrate) within the underground large opening.

Jan 1, 2003

By W. T. Swensen

The Anaconda Company, through its wholly owned subsidiary The Anaconda Company (Canada) I,td., has investigated, optioned and partially developed a large tonnage of iron ore amenable to magnetic concentration. The reserves are located in north central Ontario and occur within a twenty-two mile belt of layered and intricately folded metamorphic rocks, close to the north contact of an igneous complex of granite and pegmatite. There are two main ore deposits. Briarcliffe is a steep to vertically dipping body 100 to 500 feet wide and over a mile long. The Two Mile Lake deposit is flat dipping and confined to an open, asymmetrical syncline; it is approximately a mile wide and 250 to 4.00 feet thick. On its flat easterly plunge, it is saucer-like in shape and is amenable to open-pitting for an east-west distance of several thousand feet. Magnetometer surveys, confirmed by drilling, indicate at least a three mile eastward extension of this deposit. Location and Access: The property is located in the Kowkash Mining District of northwestern Ontario, roughly forty-four miles north of the community of Nakina on the main line of the Canadian National Railroad. (Fig. 1) Access during the exploration period was entirely by airplane from Nakina. (Fig. 2) More recently, Nakina itself was connected to the highway network in the Longlac-Geraldton area. The property is roughly 190 miles by existing and proposed railroad from the Great Lakes waterway system. The Trans-Canada pipeline moving natural gas from western to eastern Canada passes through Geraldton roughly 70 miles south of the property. Topography: The surface features in the area are typical of a sizeable portion of the Precambrian Canadian Shield area. Many lakes, low swampy areas, and glacial moraine-type features are common in this recently glaciated area. The average elevation is between 800 and 900 feet above sea level, and the relief is probably less than 100 feet with the greater portion of the area less than 50 feet. The topographic "highs" are formed either by outcrops that were resistant to glacial erosion or by moraines, eskers and drumlins which were deposited upon the recession of the glaciers. The better mineralized zones, composed chiefly of quartz and magnetite, commonly form ridges resistant to erosion and weathering. Previous Work: Because of the obvious outcrop of the magnetite-rich beds and knowledge gained from early developments within the general region, it is conceivable that the presence of the iron formations has been known for a good many years. The area is included in studies made by L. F. Kindle* in 1929 and 1930 for the Ontario Department *Kindle, L.F., Kowkash-Ogoki Gold Area, Ontario Department of Mines Annual Report, Vol. XL, Part IV, 1931; map 40f

Jan 1, 1961

By Ross Nairn

"Tulawaka Mine is a joint venture between Pangea Minerals Limited 70% (a wholly-owned subsidiary of Barrick Gold Corporation) and Northern Mining 30%. Tulawaka Mine is located in North West of Tanzania in the Lake Victoria Goldfields. Tulawaka Mine is scheduled to process 360,000 tonnes per year at an average 11.5 g/t head grade over a 4 year mine life.The Tulawaka Process Plant uses single stage crushing, single stage SAG milling, gravity, intensive leach of gravity concentrates, CIL, Zadra desorption and cyanide detoxification to process the ore. Gold recovery exceeds (or is expected to) 95%.The Process Plant was designed and constructed under the supervision of Ausenco Engineering of Australia. Site works commenced in January 2004, Process Plant construction commenced in July 2004 and the first ore was presented to the Process Plant 26th February 2005. The first gold was poured on 15th March 2005. All construction contractors were demobilized from site 7th April 2005. Major achievements have been 3.4 million hrs LTI free during construction and operation to date, training of the Tanzanian workforce at Bulyanhulu Mine prior to commissioning, a succession plan to replace expatriate personnel with Tanzanian staff and significant over performance of the Process Plant against design.INTRODUCTIONTulawaka Mine is situated approximately 160 km south west of Mwanza in the western Lake Victoria Goldfields District of north western Tanzania. The property is held under a joint venture between Pangea Goldfields Inc (70%), a wholly owned subsidiary of Barrick Gold Corporation, and Explorations Minieres Du Nord Ltée (30%). A location map showing the position of the operation in Tanzania is shown in Figure 1.Mine site staff at Tulawaka comprises a combination of Tanzanian and Expatriate personnel. All Pangea personnel live on site and commute to their place of residence for their R&R on a 9 weeks on 4 weeks off roster."

Jan 1, 2006

By A L. Zawadski, B G. Putland

"This paper discusses a method to build a calibrated comminution circuit model, using historic operating data and blend information that is useful for forecasting and optimising plant performance, as well as evaluating expansion opportunities. A preferred method for building a calibrated power-based comminution model is discussed and justified based on two case studies, offering low-cost and effective strategies to utilise existing information for the maximum possible benefit.The first example is the Lefa Gold Mine located in Guinea, West Africa operating a semi-autogenous grinding (SAG) and ball milling circuit with recycle crushing (SABC). Daily blend information and operating data was utilised to build and calibrate a power-based model of the comminution circuit. The least squares regression method was used to solve the SAG mill specific energy requirement and the operating work index (Wio) for each individual ore type. The calibrated model was used to evaluate expansion strategies to sustain throughput at higher proportions of fresh ore based on the proposed life-of-mine schedule.The second example is the Ok Tedi Copper-Gold Mine in Papua New Guinea operating a SAG and ball milling circuit (SAB). The circuit limitation would often shift between the SAG mill and the ball mill due to variable ore characteristics and feed blend. Typical SAG mill relief strategies, such as recycle crushing or secondary crushing, required significant capital expenditure and the potential throughput benefit would vary depending on ore type, making economic justification difficult. Daily blend information and operating data was used to build and calibrate a power-based model of the comminution circuit to identify ore types that might benefit from higher blast intensities to increase fines content, thus relieving the SAG mill limitation and increasing overall throughput without a major capital investment.Citation:Zawadski, A L and Putland, B G, 2016. Calibrating Comminution Models Using Operating Data to Forecast and Optimise Plant Performance, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 17–26 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By Zhen Zhang, Jiang Diao, Xuan Liu, Tao Zhang, Bing Xie, Hong-Yi Li

Extracting vanadium from vanadium containing hot metal by LD process has been proven an effective solution for the utilization of vanadium-titanium magnetite ore, but the systematic analyses of vanadium extraction rate and mechanism by basic slag are seldom reported. In this study, mathematical model of vanadium transfer from metal to slag was formulated and the rates of vanadium extraction of hot metal with basic slag were investigated. The results indicated that the apparent vanadium extraction rate constant, kp, were in the range of 1.33~9.07×10-4g/(cm3·s). And the rate constant was increased with the increase of final slag basicity, reaction temperature and stirring gas flow. The apparent of mass transfer parameter decreases significantly from 0.13 cm3/ s to 0 cm3/ s in 20min, and the data changed as negative due to the decrease of slag oxidation and recovery of vanadium from slag to metal.

Jan 1, 2015

By Rafael Pereira Ferreira

O objetivo deste trabalho consiste em caracterizar o comportamento termomecânico do aço inoxidável austenítico AISI 316L a partir dos parâmetros de encruamento (h), recuperação dinâmica (r) e recristalização dinâmica (n, t0,5). Na parte inicial das curvas de escoamento plástico a relação sc/sp = 0,92 é relativamente alta, sendo um indicativo que o amaciamento promovido pela DRV é intenso, corroborado a moderada EFE, ?sfe = 66,86 mJ/m2. Na segunda parte das curvas vê-se que há um atraso na cinética de amaciamento dinâmico com maior valor para t0,5 e menores valores do expoente de Avrami n, devido à competição entre os mecanismos DRV-DRX

Aug 17, 2017

By Y R Fu, D R. Xu, C J. Wu, G C. Hu, H Chen

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Hainan Province (Hainan Island) in South China hosts numerous Mo-polymetallic ore deposits that are genetically related to Cretaceous granitoid intrusions. Laser ablation inductively coupled mass spectrometry (LA-ICP-MS) zircon U-Pb dating and molybdenite Re-Os dating reveal three metallogenic episodes: the late Early Cretaceous (ca 112 Ma), the late Early to Late Cretaceous (ca 95–106 Ma) and the Late Cretaceous (ca 72–89 Ma). The third mineralising episode might represent the youngest Mo mineralising event in East China. Results from this study demonstrate that Mo mineralisation on Hainan Island occurred under an extensional setting that was prevailing in the late Mesozoic (ca 180–67 Ma) in South China, which was likely due to the slab rollback of the subducted palaeo-Pacific plate beneath the South China continent.CITATION:Xu, D R, Hu, G C, Wu, C J, Fu, Y R and Chen, H, 2015. Geology and geochronology of the Mo-polymetallic ore deposits in Hainan Island, South China, in Proceedings PACRIM 2015 Congress, pp 645–648 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Raymond W. Henn

The 32nd annual short course ?Grouting Fundamentals and Current Practice? was held at the Colorado School of Mines, June 13-17, 2011. The field demonstration portion of the course was conducted June 16 at Baski Inc.?s yard in Denver, CO. The full-scale field demonstration presents many types of drilling and grouting equipment in operation as well as numerous grouting methods per-formed under various field conditions. As part of the field demonstration, the class was shown the proportioning, mixing, testing and injection of various cement grout mixes into sand columns under controlled and recorded conditions. These sand column demonstrations have been conducted under controlled and measured conditions each year since 1999 as part of the short course. The sand column demonstrations were conducted prior to 1999, but with less quality control and minimal record keeping of the proportioning, mixing, testing, injection pressures and the final permeation results.

Jan 1, 2011

By Robert Bachus, Jamey B. Rosen

"Abstract Large scale In Situ Barrier Wall Construction projects, specifically those related to earth dams, dikes, and levees, frequently require stringent quality control measures to ensure the success of the wall. This presentation discusses the applications of Geographic Information Systems (GIS) technology to capture information from multiple data streams and provide geotechnical feedback, quality control, and project control feedback. Techniques used to geospatially analyze verticality data from secant piles and panels will be demonstrated. Examples will be presented from barrier wall installations at two sites owned by the U.S. Army Corps of Engineers (USACE): the Wolf Creek Dam in Kentucky, and Center Hill Dam in Tennessee.IntroductionDeep foundation installations require contractors to collect a substantial amount of information over the course of a project, both for internal quality control of construction progress and for demonstrating compliance with customer or owner specifications. Methods of collecting information are constantly improving, bringing with it the need for a systemic approach to managing the increasing amounts and types of data. Handling these diverse types of data presents challenges with both budget and schedule demands. This paper discusses some techniques for adding or increasing quality control in barrier wall constructions by consolidating, visualizing and analyzing data using relational database and Geographic Information Systems (GIS) technology, collectively referred to as Information Management System (IMS) development. The IMS concept is designed to facilitate the collection, transfer and processing of data and provide an easy way to remotely access and visualize construction progress.The remainder of this paper presents the needs and objectives of an IMS applied to quality control in barrier wall construction, the components and data flows involved, the capabilities and user interfaces of the systems and the benefits for the end users. Examples are presented throughout from case study projects including: a pile barrier wall applied in the rehabilitation at the Wolf Creek Dam in Kentucky (under contract to the Treviicos-Soletanche Joint Venture), and a secant pile barrier wall currently under construction in the rehabilitation of the Center Hill Dam in Tennessee (under contract to Bauer Foundations Corporation) (both owned by the Nashville District of the USACE)."

Jan 1, 2014

The widely accepted concept of mineral resources are that they are finite - mining therefore being intrinsically unsustainable. Yet the modern global mining industry continues to grow production at strong rates - how can this be? In reality, mining is a complex industry, starting with exploration, development, operations and then rehabilitation and closure. A recent major study of Australia has shown that for most mineral commodities, exploration continues to find new deposits, or expand resources at existing mines. In parallel, however, there are a number of key 'mega-trends' which are growing in their importance - declining ore grades (or quality), increasing tailings and waste rock volumes, the need for deeper mining, more refractory ore types, increasing energy inputs and higher unit energy costs, increasing pollution issues and, of course, not to forget greenhouse gas emissions issues. This paper will present a detailed case study of the ultimate sustainability of the Australian mining industry - showing long term historical data sets on ore grades, waste volumes and economic resources and placing these trends in light of major twenty-first century issues such as energy supplies (especially Peak Oil), climate change and existing and emerging land use conflicts (eg agriculture versus mining). Australia is a critical case study in the sustainability of mining, as it is a major global exporter of numerous commodities, and this is expected to continue to underpin the ongoing industrialisation of countries such as China and India. The ultimate question begs - can Australia actually meet this fundamental challenge, or will our resources run out, or will we be constrained by environmental issues such as climate change, land use or perhaps water? Rather than a mere optimist's or pessimist's view, this paper will present a range of hard data which underpins the debate about the sustainability of mining this century: ultimately, we cannot assume that the patterns of past mining will continue to work in the future. The sustainability of mining continues to hang in a precarious balance.

Jun 1, 2010

By Laura Mottola

Process Design and Change Management for Successful Deployment of Technology in Mining Over the last 30 years Canada has been successful in developing but not deploying hardrockmining automation. Our opinion is that the current lack of R&D investment and implementation capacity places Canada at risk as a future global mining leader A white elephant A burdensome possession; creating more trouble than it is worth. White (albino) elephants were regarded as holy in ancient times in Thailand and other Asian countries. Keeping a white elephant was a very expensive undertaking, since the owner had to provide the elephant with special food and provide access for people who wanted to worship it. If a Thai King became dissatisfied with a subordinate, he would give him a white elephant. The gift would, in most cases, ruin the recipient.

May 1, 2010

By Mahyera A, Sakashita B, Ahmed U, Abou-Sayed AS

Gas in U.S. coals is primarily composed of 90 to 99 percent methane and up to 10 per- cent carbon dioxide. In composition and heat- ing value, this coal-bed gas is similar to natural gas and can be introduced directly into commercial pipelines after standard condition- ing. The high permeability cleat system in the virgin coal can be exploited in order to drain the coal gas well in advance of mining. Two premining drainage methods have been extensive- ly evaluated in the U.S.; they are 1) horizon- tal boreholes collared from within the mine, and 2) vertical drilling from the surface with fracturing. Limited-size fracture treatments are advocated in order to prevent potential roof damage and the need for added support. An engineering approach to predicting gas flow for different drainage techniques near mining locations is presented. Results can be used in design, i.e. pipeline, compressor. Coal gas drainage from a horizontal borehole and a treated (contained fracture) vertical well for a 6 foot seam have been evaluated. Based on these results, it was concluded that selection of gas drainage techniques will depend primar

Jan 1, 1982

By Ketan H. Trivedi

This paper describes the method of analyses used for the design of temporary and permanent Secant Pile Walls, describes various aspects of construction including, guide walls, sequence of pile installation, plan alignment and verticality tolerance, methods of drilling (auger, wash boring, cased and open holes), lateral bracing for secant piles, cutting of keys in secant pile walls for the connection of permanent floor slabs, sealing of water leaks and waterproofing. The paper concludes with a brief case history of a secant pile wall project recently constructed in New York City.

Jan 1, 2006

The Clyde Power Project, and its Clutha Valley Development forerunner, has taken widespread investigations for various hydroelectric purposes both along the valley floors upstream from Alexandra and on the higher schist terrain. As part of this work the nature and extent of many of the alluvial deposits have been resolved and the ages established with varying precision. Gold values have been approximately appraised in some areas as an element of environmental assessment.

Jan 1, 1992

By B Orchard

New Zealand SteelÆs Waikato North Head mine, situated at the mouth of the Waikato River, supplies approximately 1.2 million tonnes per annum of titanomagnetite concentrate to the Glenbrook steel mill. The mine draws its fresh water supply from the Waikato River, abstracting approximately 38 000 cubic metres per day. During the concentration process of the ironsand, slimes are liberated into the plant wastewater. The plant wastewater, storm water and groundwater from the mining operation is treated and passed through settling ponds. Around 118 400 cubic metres per day of water are drawn from the recycle settling ponds for use in the concentration plant. Typically a daily average of up to 15 100 cubic metres of the treated water is discharged back to the Waikato River. Since the early 1990s significant improvements have been made to the water treatment at Waikato North Head mine and regularly the mine discharge water quality is similar or better than background river water quality.

Jan 1, 2002

By Robert Rautenberg, Paul McDermott

This paper will discuss the construction of 15.9 km (9.88 mi) of tunnels on a project in Chicago, Illinois. The tunnels were driven utilizing two rock and four soft ground TBMs ranging in sizes from 7.39 m (24.25 ft) in rock down to 1.95 m (77 in) in soft ground. In addition to the mining, there are 63 upper level structures and 16 dropshafts averaging 61.5 m (202 ft) deep included on this project. Many diverse mining, excavation, support and lining techniques were employed on this project.

Jan 1, 1997

By Arun Kumar Singh

Wide variation in the nature of the coal seams and the surrounding rock mass of the Indian coalfields and very little information about the associated stress fields were observed to be the major hurdles in the straight forward application of a continuous miner (CM) based mechanised depillaring approach. Due to various techno-economic reasons, a considerably large number of coal seams have been developed and are standing on pillars in India. The development of pillars is done as per Indian coal mines regulation, which results in pillars of relatively large size. In fact, the large size of the pillars provides stiff natural support to control caving of the massive overlying strata. However, the size of these pillars is not conducive for the single pass pillar stripping technique and, therefore, there is a need for pillar splitting before pillar extraction/retreating. Splitting of the pillar may reduce the competency/stiffness of the pillar, which creates a chance of overriding during final extraction below a massive roof stratum. This paper first discusses the existing coal mining scenario in India followed by a brief presentation of geo-technical details of pillar extraction at the three sites where a CM has been introduced for depillaring/pillar retreating in the country to date. Based on past rock mechanics experiences with conventional depillaring faces, stability issues of the pillars, fenders, and stumps in and around the depillaring face are discussed. This may prove to be an important factor in the success of future CM faces. It is recognized that the application of the modern strata movement monitoring techniques may improve operation safety by providing valuable qualitative and quantitative information that can be used to improve the design of modern concepts like roof bolt based breaker line support during pillaring.

Jan 1, 2009