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By Elwyn H. King, Thomas R. Kuesel

I. CONCEPT MARTA's Peachtree Center Station is being mined out of hard rock, directly beneath Atlanta's central business district, with minimal surface disruption during construction. Its cost is competitive with that of a conventional cut-and-cover alternative owing to its design concept, which utilizes the rock as a primary structural and architectural material. II. PLANNING The station was originally planned for cut-and-cover construction. However, Peachtree Street is unusually narrow for a main business street (generally 78 feet (24 m) between building lines) and cut-and-cover construction would therefore be very disruptive to surface traffic and severely restrict access to adjacent buildings, including Peachtree Center, Atlanta's showcase business/commercial complex. (See Fig. 1.) Tunneling had been considered, but was initially thought [ ]

Jan 1, 1979

By M Angus, S Konopa, A Virisheff, S Crispin

A positive mill reconciliation at a mine is a double-edged-sword. Much back slapping happens. The bank and the board can’t get enough until the downside becomes apparent. Over a prolonged period, there becomes an issue with market perception and the potential for shareholders to be misinformed regarding the potential value of the project. In addition, there are impacts on mine scheduling, waste allocation (or lack thereof), government expectations, and the potential for misguided external assumptions regarding the ‘unexpected’ results. The PT Agincourt Resources Martabe Gold Mine has shown a significant under-call, in the order of 20% total gold metal, between the Mineral Resource (MR) estimates and Grade Control (GC) estimates since production commenced in 2012. Recently, the under-call has been reduced by incorporating the use of grade control drilling in the MR grade estimates. Despite recent improvements in reconciliation, drilling in 2017 at both Purnama and Barani open pits shows that infill reverse circulation (RC) drill holes often produce significantly higher grades than those predicted in the MR block model. CITATION: Angus, M, Virisheff, A, Konopa, S and Crispin, S, 2018. Martabe Gold Mine, Indonesia: a positive solution for positive reconciliation, in Proceedings Complex Orebodies Conference 2018, pp 76–78 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By K J. Grohs

Martabe gold and silver mine is situated in northern Sumatra and comprises several deposits in steep terrain that are required to be developed in the optimal sequence for the best possible Net Present Value (NPV) return on the project. In addition, the waste from the excavations is a by-product to be scheduled and used for construction of the tailings storage facility (TSF). These plans need to be aligned to ensure the tailings can be contained relative to the production rate. The TSF embankment construction includes potentially acid forming (PAF) waste that needs to be progressively sealed and rehabilitated to meet the closure requirements of the future.The mine is situated approximately 3 kilometres north of the township of Batangtoru in a seismically active zone between the off-shore subduction zone and the trans Sumatran fault. The mining operation currently includes two open cut pits with a third in development stage, an integrated TSF and dualpurpose valley-fill type waste rock storage facility (WRSF) and TSF embankment. Mine waste is used in construction of the WRSF / TSF embankment, including PAF waste rock, which needs to be scheduled for optimal use in construction activities in a manner that mitigates future acidic and metalliferous drainage (AMD) risks (Pearce and O’Kane, 2017).The Life-of-Mine (LOM) plans must satisfy both optimal pit development to maximise NPV and suitable delivery of waste for effective TSF construction matching the rate of rise of tailings, and consider AMD management, progressive rehabilitation and ultimately effective sustainable mine closure. This paper outlines the methodology to optimise the system to deliver these potentially opposing objectives.CITATION:Grohs, K J, 2018. Martabe integrated life-of-mine optimisation, in Proceedings Life-of-Mine 2018, pp 83–86 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By S. Hölz, M. Jegen, K. Reeck, A. Haroon

Past investigations of seafloor massive sulfides (SMS) focused on actively forming sites. New technologies are needed to explore for SMS deposits which have finished their active phase and are possibly covered by sediments or lava. For this purpose the new marine transient electromagnetic (TEM) induction system MARTEMIS was developed by GEOMAR. The system was used for investigations in the Tyrrhenian Sea (Palinuro Seamount) and at the Mid-Atlantic Ridge (TAG area) and proved to be suitable for operations at shallow (~600m) and great water depths (~3600m) in steep and difficult terrain. Calibration measurements in the water column demonstrate that it is possible to acquire high quality data, which is fit to be evaluated in terms of inversions. However, these calibration measurements also demonstrated that great care has to be taken in the design of such an inductive coil system, because relatively small metal structures attached to the system may lead to significant static distortions in the measured transients. The interpretation of TEM data acquired at the Palinuro Seamount show a conductive layer in the vicinity of a previously drilled, buried SMS occurrence and serve as proof of principle of the system. Results also indicate that the conductive SMS unit is indeed a confined layer with limited thickness between 3 – 5m, which was not known from previous drilling. In a similar manner, results also hint at an unknown mineralization at depth in a second area of the Palinuro Seamount. Investigations by TEM measurements were accompanied by measurements of the ambient electric field (→ self-potential) and seafloor temperatures with a heatflow probe as well as direct sampling with a gravity corer. The areal coverage of measurements and sampling allow for a greatly enhanced view of the structure.

Jan 1, 2018

By J. L. Parks

Designs, installation procedures, and performance characteristics of martensitic cast steel concaves are reviewed. Longer wear life, fewer pieces to install, and eliminating the need to scarf joints are the principal benefits of using martensitic steel to replace austenitic 12% Mn (Hadfield's) steel, the traditional concave material for large gyratory crushers. Installation procedures that reduce the risk of breakage are described. Operating practices that affect concave performance are also discussed.

Jan 1, 1992

By R Butler

Contract m1n1ng in New Zealand developed in the coal industry and has become an element in the success of recently opened hard rock gold mines. At Martha Hill, the mining contractor is undertaking a wide range of activities from open pit mining, crushing, conveying, waste embankment construction and drainage.

Jan 1, 1991

Martha Mine is an open pit gold-silver mine, located within the township of Waihi, 150km southeast of Auckland and is operated as a joint venture between Normandy Mining Ltd. 67 %) as Manager and Otter Gold Mines Ltd. (33%). The deposit was historically mined, by underground methods from 1888 to 1952, producing 5.5 moz of gold and 30 moz of silver, from 11 mt of ore. The current operation began in 1988, producing, to June 1999 - 867,245 oz of gold and 5.5 moz of silver from 9.5 mt of ore. The licensed reserves were due to be mined out by late 2000. Consents were granted in December 1998 to allow the expansion of the operation through to 2007 accessing an additional 7.5 mt of ore at 3.4 gpt Au and 26.0 gpt Ag for 800,000 oz of gold and 6.4 moz of silver. The key elements of the expansion are: 1. Pit enlargement 2. Upgraded crushing and material handling facilities 3. Construction of a second tailings storage facility 4. Upgraded water treatment capacity 5. Increased operating capacity This paper presents an update of expansion activities to date.

Jan 1, 1999

By K M. Brodie, D I. K McLeod, J Ruddock

Environmental incidents involving mine tailings and waste rock inevitably become highly publicised and serve to damage the credibility of the entire industry. The recent serious incident involving a spill from a Romanian mine, was blamed for triggering æone of the worst environmental catastrophes in Eastern EuropeÆ. It is important to clearly demonstrate to the general public that these incidents are not representative of the industry as a whole. Where such incidents have occurred, the causes are generally related to poor design and/or construction, inadequate supervision and/or monitoring and maintenance, lack of independent expertise, inadequate risk identification and treatment and no provision to ensure that rehabilitation and long term management of the site occurs. Many people are unaware that these issues have been considered and provided for at the Martha Mine. Despite the fact that the first tailings storage facility has performed very well over fifteen years of operation, the long term safety and security of the tailings storage facilities continues to be questioned and debated by the public. The best way to address this is to provide quality information to enable a better understanding amongst the general public.

Jan 1, 2002

By R. Corriveaau

This paper is about a horizontally curved conveyor, which carries 6,050 stph of limestone over land from a new quarry to the owner's plant. The conveyor is 5,012 ft long with a horizontal curve radius of5,OOOft Site conditions made a curved conveyor design the most optimal and economic solution. Using our unique custom conveyor calculation program, TKRI was able to accurately model and design the conveyor to properly track the belt and prevent any spillage through the horizontal curve radius. A data monitoring system was installed that allows monitoring of the conveyor both locally and remotely. The remote monitoring allows TKRI to contact the owner for preventive maintenance. Preventive maintenance can reduce the conveyor downtime during normal operating hours.

Jan 1, 2004

By Curt Swanson, David C. Mathy, Dru R. Nielson, Kent VonAspern

In 1997, Central Contra Costa Sanitary District undertook the design of the Martinez East Side Trunk Sewer Improvements Project. Microtunneling was specified for approximately 1,035 meters (3,400 feet) of 600-mm (24-inch)diameter pipeline to be installed through estuarine soil deposits (San Francisco Bay Mud) and alluvium beneath the congested city streets of downtown Martinez, California. Directional drilling was specified for approximately 275 meters (900feet) of 200-mm (8-inch) diameter pipeline in four separate segments to be drilled through bedrock within narrow utility easements between residential properties. This paper presents a case history for the design and construction of themicrotunneling and directional drilling aspects of the project.

Jan 1, 1999

By Joseph Hoang, Nick Reed, Scott Wishart, Michael Lovitt

Marvel Loch Underground forms part of St Barbara Limited’s Southern Cross Operations which is located 360km (224 miles) east of Perth. Southern Cross Operations produces approximately 120,000 ounces of gold each year. Mining occurs in over 8 lodes using a variety of stoping methods including Uphole Benching, Long Hole Open Stoping, and Core and Shell.

Jan 1, 2012

By AIME AIME

THE difficult problem of visitors is being met by the Hudson Coal Co. at Scranton in an ingenious fashion. The Company had long made it a point to have dealers selling its coal visit the mines, whenever possible. "The excellent reaction obtained from these dealer visits brought up the question of whether it would not be possible to open one or more mines to the public, and give the consumer an opportunity of seeing for himself how anthracite is mined and prepared. Ac-

Jan 1, 1929

By Carrie Smith

Along Michigan’s Upper Peninsula lies the Marquette Iron Range, home to iron mines. Just southeast of the region is the small town of Iron River, where Mary Korpi spent most of her chidhood and early adulthood. Though living in the heart of mining country, the industry did not pique her interest while growing up. As the daughter of two educators, she envisioned a different future for herself. Now, decades after working for one of the largest gold companies, she is gearing up for her term as the Society for Mining, Metallurgy & Exploration’s 2026 President.

Mar 1, 2026

By H Chalcraft, T D. Mullen

Conditions encountered at a recently completed brownfields mining project provided valuable insight into, and development of, techniques for working in and around known underground mining voids in an open cut environment. The careful application of underground blasting principles to a pit environment and successful excavation whilst maintaining appropriate stand-off distances were two primary areas of innovation enabling the success of the project.Mary Mac Hill is a gold deposit situated less than 2 km south-west of the town of Laverton, Western Australia. It is owned and mined by Crescent Gold Limited. Previous underground mining by various other mining companies has left an extensive network of underground horizontal development, subvertical stopes and shafts, some of which daylighted at surface. This was identified as potentially posing substantial risks, which would prevent the application of conventional mining methods. Two major stopes were located under a hard banded iron ridge topped by a peak of cap, connected variously by narrow drives and vertical development. Due to the proximity of the first of these stopes to the surface, its dimensions and governed by procedures and advice provided by externally engaged engineers, Crescent Gold could not access the area of the ridge immediately overlying the stope using conventional open cut mining methods. This was the first of many hurdles surmounted in mining this deposit.The following report outlines how the challenges this geometrically complex deposit presented. Solving these problems enabled the team to mine the contained gold ore to a completed design, without subjecting personnel or mining equipment to harm due to a void breach incident. This paper outlines the numerous complications and difficulties Mary Mac Hill posed and explains the strategies developed to overcome them. The report also presents technical mass blasting details explaining two of the critical crown pillar blasts.CITATION:Mullen, T D and Chalcraft, H, 2012. Mary Mac Hill - The challenges and strategies of successful open cut mining: A complex underground gold deposit riddled with a network of complicated voids, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 89-96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

The first record of coal anywhere in the Appalachian regions of which we now know is along the north fork of the Potomac River, above the mouth of Savage River, on a map entitled, A Plan of the upper Part of Potomack River call Cohongorooto Survey'd in the Year 1736. Benj. Winslow1 two "Cole-mines" are shown, one just above Green Island and the other just below Hopwood Run. Winslow was in charge of a surveying party to "Lay out the Bounds of the Northern Neck of Virginia," or Lord Fairfax's Grant, his party locating the liver above the mouth of the Shenandoah, while another party located it below that point, and then around Chesapeake Bay and up the Rappahannock River. The results of the two surveys were combined in a map called, The Courses of the Rivers Rappahannock and Potowmack, in Virginia, as surveyed according to Order in the Years 1736 & 1737, made by Wm. Mayo, which does not show the "cole-mines;" this map was used with the report of the boundary commission which was sent to London in the case before the Privy Council. The boundary line decided upon was surveyed on the ground in 1746, just ten years after the original one. The results of this work were shown on A Map of the Northern Neck in Virginia, According to an Actual Survey begun in the Year MDCCXXXVI, and ended in the Year MDCCXLVI, Drawn by Peter Jefferson And Robert Brooke, Surveyors, which is now in the Colonial Office in London. This map shows the "cole-mines" in the same location as on Winslow's map, and taken from his record, of course, as that part of the survey was not retraced. Faulkner, who examined all of these records in his review of the case in 1832, refers to the notes of the original survey as "No. 10. The original field notes of the survey of the Potomac River, and the mouth of the Shenandoah to the head spring of said Poto¬mac River, by Mr. Benjamin Winslow." While the notes of the 1746 survey are in the London records and photographic copies of them are in several libraries in this county, the notes of the 1736 survey cannot be found anywhere. (For Chas. J. Faulkner's report, dated Nov. 6, 1832, see Kercheval's History of the Valley of Virginia, pp. 160-173. Jas. W. Foster's Maps of the First Survey of the Potomac River, 1736-37, in Wm. and Mary College Quarterly History Mag., April, 1938, gives a complete history

Jan 1, 1942

Maryland Geological Survey, Johns Hopkins University, Baltimore, Md Edward B Mathews, State Geologist A list of publications-and maps will be sent upon request. The Survey published 12 general reports between the years 1897 to 1928, inclusive Vols. 1 and 9 are out of print, others may be obtained at the uniform price of $1 each. Separates of many of the papers contained in the volumes may be had; in the following list a few of the available separate papers of most direct interest are cited. Vol. 1, pt 4, Bibliography and cartography of Maryland, by E B. Mathews (1897), 25 cents, vol 5, pt 4, Report on the coals of Maryland, by Clark and others (1905), 25 cents paper bound, vol 6, pt 1, The physical features of Maryland, by E B. Mathews, W. B. Clark and others (1906), 25 cents paper bound, including map, 75 cents, vol 8, pt 2, Maryland mineral industries (1896¬1907), by Clark and Mathews, free, vol 8, pt 3, Report on the limestones of Maryland, by E B Mathews and J. S Grasty (1909), 25 cents paper bound, vol 9, pt. 3, Report on the iron ores of Maryland, by J T. Singewald, Jr. (1911), 25 cents paper bound, vol 10, pt 1, The geography of Maryland, by W B. Clark (1918), 25 cents paper bound Vol 11, pt 1, The coal formations and mines of Maryland, by various authors (1922), 35 cents paper bound, vol 11, pt 2, The fire clays of Maryland, by various authors (1922), 35 cents paper bound Most of a series of Systematic Reports on the geologic formations found within the state are also available: Pliocene and Pleistocene, $1; Upper Cretaceous, $5; Lower Cretaceous, $5, Triassic (in preparation), Carboniferous and Permian (in preparation);

Jan 1, 1933

By Libby R. Ricafort, Victorio V. Pato, R. S. Pizarro

Introduction Atlas Consolidated Mining and Development Corp. (ACMDC) started gold production at its Masbate gold mine early in 1980. This involved an open-pit mine and a 3.5-k/d (3850-stpd) carbon-in-pulp processing facility (Pizzaro and Antonio, 1981). When this operation started, the mine began stockpiling sub-grade milling material averaging 1 g/t (0.029 oz per st) gold. Furthermore, geologists estimated that there were additional low grade reserves within the ultimate pit limits. These amounted to 2.4 Mt (2.6 million st) with an average grade of 1.1 g/t (0.03 oz per st) gold. The success of low cost heap leaching prompted an investigation to determine if this tech¬nique would be applicable for the low grade Masbate ore. The findings were favorable and a series of laboratory tests were undertaken. These tests indicated the amenability of this subgrade milling ore to heap leaching. Depending on ore size, gold extractions of more than 60% were obtained. To further define operating parameters for a commercial heap leaching plant, a 400-t (440-st) batch pilot plant was built and operated. These test results were used to design the first commercial heap leaching plant in the Philippines. One design concern was the control of solutions during the rainy season. Due to the material's low grade, every effort was made to minimize capital and operating costs. To this end, surplus mining equipment from the copper operations of ACMDC and used machinery in the crushing circuit were considered. Location: The Masbate gold heap leaching operations are located on the northeastern part of Masbate Island, Philippines. This is about 480 km (300 miles) south-east of Manila. Climate: The climate is moderate with two distinct periods. The dry season runs from January through June, and the rainy season extends from July through December. During the wet season, the rainfall at the mine site averages 300 mm/m (11.8 in. per month) for a total of about 2000 mm/year (78 in. per year). However, heavy downpours in excess of 100 mm/h (4 in. per hour) can occur. Geology: Four distinct rock types have been identified in the pit area. They are tuffaceous agglomerates, andesitic agglomerates, metasedimentary rocks, and hornblende augite andesitic porphyry. The tuffaceous agglomerate occupies the northern and western flanks of the mine. Andesitic agglomerates are localized distinctly in the central portion of the volcanic plug within the mine site. The eastern boundary of the mine is occupied by metasedimentary rocks, whereas, the hornblende augite andesitic porphyry occurs as an intrusive within the andesitic agglomerate and tuffaceous agglomerate. Some areas of the pit contain high proportions of clay minerals, requiring an agglomeration step in the flowsheet. This ensures satisfactory percolation through the heaps. Ore characteristics: Gold and silver are microscopically dis-

Jan 9, 1987

By Wilbur Nelson

IN 1839,1 Gerard, Troost, the first, State Geologist of Tennessee, reported the occurrence of zinc ores in East Tennessee, in connection with the iron ores at Embreeville; in 1844,2 he refers to the zinc deposits of East Tennessee, especially the apparently rich deposits occurring, in Jefferson and Claiborne Counties, while his ninth annual report is a ,description of the zinc deposits of Jefferson County and a description of the most improved processes by which zinc is extracted from its ores. Although. Tennessee has long known of the occurrence of its zinc deposits and has recognized their value, only during the last few years have these ores been successfully worked. As far as can be learned, prior to the systematic development of the Mascot district in 1911, no large-scale or successful operation of any of the zinc deposits was carried on. But in that year, after several companies had made considerable progress in developing the Mascot area and had proved. a relatively extensive body of low-grade sulfide ore, the American Zinc Co. entered the field. It introduced modern methods of prospecting and mining the ore and from the first was successful. Too great credit cannot be given this company for its pioneer work in a previously unimportant field. Throughout the history of its operations, the American Zinc Co. has confined its efforts to underground mining of the sulfide ore, sphalerite. This company has found that successful results in zinc mining in East Tennessee can be achieved only by expending large sums in prospecting and blocking out bodies of pay ore in sufficient magnitude for large-scale operations. At Mascot are located the mines of the American Zinc Co. of Tennessee, the mines being situated along the Southern Railway in the Holston River Valley, Knox County, about 13 miles northeast of Knoxville. Considerable mining and prospecting had been done by several companies prior to the acquisition of this property by the, American Zinc Co. Previous to 1900 only open pits, which were worked for oxidized ores, were operated. and the production was small. In 1900 the

Jan 10, 1924

By F. B. Samani, B. Stabel

The 1,000 MW Hydro Power Station Masjed-e-Soleiman (formerly called Godar-e-Landar) in Iran is under construction since 1992. The rock engineering aspects of the major underground structure, i.e. the powerhouse cavern shall be reported on in detail. The geotechnical investigations are described and results given. The results of several geotechnical analyses are presented. The designed and executed rock support is given. A description of the monitoring systems and typical measurement results obtained during and after excavation are presented. The lessons learnt during construction of the Stage-I powerhouse cavern were applied on the extension of the powerhouse cavern, which is to house an additional 1000 MW. Details regarding the unexpected behaviour of the Mudstones are given. Die 1000 MW Wasserkraftanlage Masjed-e-Soleiman (vormals Godar-e-Landar genannt) befindet sich seit 1992 in Bau. Dieser Artikel berichtet im Detail über die felsbaulichen Aspekte der Untertagebauwerke, insb. der Maschinenkaverne. Die geotechnischen Untersuchungen werden beschrieben und deren Ergebnisse wie die Ergebnisse verschiedener Berechnungen werden präsentiert. Die geplante und die ausgeführte Felssicherung wird angegeben. Die eingebauten Überwachungseinrichtungen werden beschrieben und typische Ergebnisse während des Aushubs und danach werden dargestellt. Die Erfahrungen beim Aushub der Kaverne der Stufe I wurden beim Entwurf der Kaverne der Erweiterungsstufe II, die weitere 1000 MW beherbergen wird, berücksichtigt. Details zum unerwarteten Verhalten des Schluff-/Tonsteins werden angegeben. La centrale hydroélectrique de Masjed-e-Soleiman (dénommée anciennement Godar-e-Landar), d’une puissance de 1.000 MW, est en construction depuis 1992. Un rapport détaillé sera présenté sur les aspects relatifs à la construction en enrochements de l’aménagement souterrain principal, à savoir la caverne abritant la salle des machines. Une description des investigations géotechniques réalisées y est fournie ainsi que les résultats correspondants. En outre sont présentés les résultats de plusieurs analyses géotechniques. L’ancrage dans la roche tel que projeté et réalisé est présenté. Une description des systèmes de contrôle ainsi que les résultats de mesures typiques obtenus au cours des travaux d’excavation sont donnés. Les leçons tirées lors de la construction de la Phase 1 de la caverne de la salle des machines furent appliquées à l’extension de la caverne de la salle des machines, qui doit abriter une unité supplémentaire d’une puissance de 1.000 MW. Par ailleurs, des détails sont donnés sur le comportement inattendu des argilites.

Jan 1, 2003

By Rodger Andrews

High cost - low productivity mining methods at the Homestake Mine forced the need for a new and safer means of ore extraction. Vertical Crater Retreat (VCR) was introduced in 1978 and accounts for over 50% of the underground mine production today. Many advantages can be attributed to this form of "bulk mining"; including steady production, decreased labor costs, and the ability to mine bulk stopes in the lower portion of the mine. However, safety and high productivity are the two major advantages. This paper will deal specifically with crater blasting and the application of mass blasting techniques in Vertical Crater Retreat slopes.

Jan 1, 1988