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By Stephen M. Smading

Unique onsite assembly of a 12.43 m Main Beam TBM and back-up system was completed on September 18, 2008 in the remote mountains of the Sichuan province of China. The equipment was assembled onsite, without previously having been assembled and tested in a factory, utilizing a method called Onsite First Time Assembly (OFTA). The Jinping-II hydroelectric project features four parallel headrace tunnels approximately 18 km long, two of which will be excavated by TBMs and two by drill and blast. A nearby fifth tunnel is being excavated by a 7.2 m TBM to draw down ground water in advance of excavating the headrace tunnels. This paper addresses the following topics: ¦Project description including geology and terrain; ¦The decision process leading to onsite first time assembly, the assembly process and logistics, and lessons learned; ¦Design features of the TBM and back-up system; and ¦Operational history from startup to the writing of the paper.

By S. M. Runke

"During the past three years the Bureau of Mines has carried on an extensive research program at the Rolla Laboratory for the beneficiation of low-grade Arkansas baixites by ore dressing methods. As a result of this study a 50-ton pilot mill was designed and constructed at Bauxite, Arkansas, by the Bureau to continue the investigation on a semi-commercial scale. The built both to reduce the experimental work to practice and to obtain operating data that cannot be determined by laboratory or small scaleTen samples of bauxitic material were mined and stockpiled at the plant site to ensure an ample supply of material for milling in the pilot plant. These samples were obtained from various bauxite deposits in Saline and Pulaski Counties, Arkansas. The deposits were selected as typical of a wide range of bauxitic material which would necessitate treatment under different conditions and by various concentration methods. All of the samples contained a higher silica content than permissible in Bayer-grade bauxite and several contained so much iron oxide that the available alumina content of the ore was mate¬rially lowered. From data obtained by milling operations on these ten samples, milling characterietics of most of the ores in the district should be predictable. This paper summarizes the results obtained in the laboratory testing of representative samples of each stock pile, and the results of small scale continuous testing of the composite sample of the ten stock piles in the gravity-flotation pilot plant at the Rolla Laboratory."

Aug 1, 1946

By C. Velásquez, W. Bergholz, C. Spence, P. Lind

NuevaUnión SpA (NuevaUnión) is a development project located in the Huasco province of the Atacama region of Chile. It is held in a joint venture company owned 50:50 by Teck Resources Limited (Teck) and Newmont Goldcorp. It includes the Cu-Mo Relincho deposit and the Cu-Au La Fortuna deposit, with plans to utilise a single concentrator to be built at the Relincho site. The Relincho site is at an altitude of 2,000 masl and is 40 km from the La Fortuna site which is at an altitude of 4,100 masl. The project is currently completing a Feasibility Study and is reviewing equipment selection and flowsheet options. This paper is based on the current thinking, and design decisions will be finalized at the completion of the Feasibility Study. NuevaUnión is currently planning for phased operation, processing Relincho ore at 104 ktpd followed by processing ore from La Fortuna at 116 ktpd. Plans for the third phase include doubling the main processing lines and returning to Relincho ore at a processing rate of 208 ktpd. The NuevaUnión concentrator will incorporate comminution and flotation circuits that are being designed to maximize the overall economic value of the combined ore deposits. Major ore characteristics differ between the two ore bodies, such as ore competency, grindability, liberation grind size, pulp rheology, tailings properties, minerals and metals of value, as well as gangue mineralogy. Mineral processing choices have been made to optimise value from each deposit and the combined project. INTRODUCTION Between 2010 and 2013, two significant mining projects were being developed in Chile: Goldcorp’s El Morro project had recently finalized a Feasibility Study and, in 2011, had received its environmental approval for construction; and Teck Resources Limited’s (Teck) Relincho project was finalizing a Feasibility Study and preparing its Environmental Impact Study. Both projects were: Geographically close, at only 40 km apart. Considering similar infrastructure. Each was planning to have its own concentrator, tailings management facility, high voltage power line, port, concentrate transport system, seawater desalination plant and pumping system to mine site.

Jan 1, 2019

By D Craw

At Reefton, mesothermal gold deposits occur in the Ordovician Greenland Group basement and bituminous coal deposits occur in overlying Eocene Brunner Coal Measures. These different resource types occur in close proximity to one another in the same topography, vegetation and climate. Both types of resources have been mined for many years and as a result historic mining areas discharge water with chemistry reflecting the mineralogy of the deposits. Coal measures release natural acid rock drainage throughout the region due to oxidation of pyrite in coal and associated sediments. Levels of acidity are increased in mining areas, and pH near three is common. Gold mines contain pyrite, arsenopyrite and stibnite. Discharge waters from these sites have pH near seven because of the high acid neutralising capacity of the basement rocks. Both coal and gold mining sites have iron oxyhydroxide precipitates in drainage waters. These precipitates are more abundant at gold mining sites, and one deposit is up to 5 m thick. Iron oxyhydroxide at coal mine sites contain Zn (up to 89 ppm), Ni (up to 10 ppm), As (up to 163 ppm), Cr (up to 23 ppm), Pb (up to 16), and Cu (up to 11 ppm). Jarosite group minerals have been identified in the coalmine iron oxyhydroxide, although most of the material is amorphous. Gold mine iron oxyhydroxide contains Zn (up to 353 ppm), Ni (up to 592 ppm), Cr (up to 17 ppm), Cu (up to 72 ppm), Pb (up to 29 ppm), Sb (up to 230 ppm), and this material is particularly high in As (up to 20 wt per cent). Most of the material is amorphous but distinctive zones (mm scale) are As rich (up to 30 wt per cent As oxide). Pharmacosiderite, K2Fe4(As04)3 (OH)5.6.3H20, is a secondary mineral in one deposit. These iron oxyhydroxide deposits are useful indicators for the metals mobilised into the environment by oxidation in the historic workings.

Jan 1, 2003

By Frank J. Wiebelt

Under a general program to extend the resources of mineral deposits, the Bureau of Mines examined the Quien Sabe antimony mine in October 1948. The preliminary evaluation demonstrated that a diamond-drill program was warranted co establish the tenor and persistence of the veins and permit an estimation of antimony reserves. The Bureau of Mines conducted a diamond-drilling program on the property from December 1949 to May 1950. Ten holes aggregating 2,483 feet were drilled. Nine of the holes encountered antimony-bearing vein material.

Jan 1, 1956

By D N. Castendyk, J L. Mauk

The world-class Waihi (>6.6 Moz Au, >41.8 Moz Ag) and adjacent Favona (>0.5 Moz Au) deposits are within a single volcanic-hosted epithermal Au-Ag district located in the southern Coromandel Peninsula, New Zealand. Gold and silver mineralised quartz veins at both deposits are hosted in porphyritic andesite flows of the Waipupu Formation. Both deposits have veins surrounded by intense widespread hydrothermal alteration that is characterised by the assemblage of quartz, pyrite, adularia, illite or interstratified illite-smectite, plus less common chlorite and albite, which is locally overprinted by minor calcite or rare kaolinite. Quantitative mass transfer calculations using Gresen's general metasomatic equation indicate that hydrothermally altered andesite at both deposits is enriched in silicon, potassium, rubidium, barium, sulphur, gold, arsenic and antimony, whereas sodium, strontium and calcium are mostly lost. Iron and magnesium show mixed gain and loss. Element gain or loss can be directly related to the prevailing alteration mineralogy. Addition of potassium, rubidium and barium coupled with the concomitant loss of sodium, strontium and calcium in intensely altered wall rocks corresponds to the replacement of plagioclase by adularia or illite. Partial retention of sodium and calcium reflects the presence of hydrothermal albite and calcite, respectively. Mass balance calculations show distinct element gain and loss that can be related to the intensity and type of alteration mineralogy. However, because most rocks are intensely altered and the progression into less altered peripheral rocks is not observed in this study, the lateral extent of elements gain or loss is unconstrained with anomalies extending at least 200 to 300 m away from major veins.

Jan 1, 2003

By Ron Millions, J. A. Folinsbee, Ishwinder Grewal, Michael Fullam, Don Strickland, Tony Y. Chong

"Since milling began in 1912, the Dome mill, now part of the Porcupine Joint Venture (PJV), has been expanded several times, the most recent increasing the milling rate from 3,500 to 11,500 tonnes per day. Dome uses conventional crushing and grinding followed by gravity concentration to recover free milling gold. A cyanidation/CIP process recovers the remaining gold in the gravity tails.Over the past few years, continuous gravity improvements have increased the gravity recovery from 20% to nearly 50% of the plant feed gold. This paper describes some of the factors that have contributed to this dramatic increase, and suggests how gravity recovery can be further improved. Gravity circuit availability has been improved to >98% with the implementation of a preventative maintenance program. More Knelson concentrators have been added to the circuit, and in 2002, an Acacia Intensive Leach Reactor was installed to replace the shaking table. In 2003, the entire gravity circuit was audited to evaluate and quantify the circuit performance. The metallurgical and mechanical operating conditions of the gravity circuit are now well understood, and areas for further improvement are well defined.INTRODUCTIONThe Porcupine Joint Venture was formed in 2002 between Placer Dome Inc. and Kinross Gold Corporation. One of the goals of the JV was to use the milling capacity of the Dome mill to process ore from Placer Dome and Kinross mines in the Timmins Camp. The PJV Dome Mill utilizes gravity concentration, cyanide leaching and carbon in pulp gold circuits to recover gold. Gravity recovery has been used in some form at the Dome Mill for most of its existence, first using conventional jigs, these being replaced in 1993 by two Knelson Concentrators, one for each of the two grinding circuits in the Dome mill. Over the years more concentrators have been added to improve the gravity recovery, most recently in 2002 for a current total of five. Also in 2002, an Acacia Intensive Leach Reactor was added to process the Knelson concentrate, replacing the shaking table."

Jan 1, 2004

By Flavio Begazo Mamani

Recientemente Southern Perú desarrolló un nuevo proyecto donde se modernizaba la planta de Fundicion y se reemplazaba el convencional horno reverbero por la tecnología del ISASMELT, capturando más del 92% de los gases generados durante el proceso de fusión de los concentrados de cobre. En ese sentido, el presente texto describo los efectos de la modernización de la Fundición sobre la calidad anódica. Antes de la modernización de la Fundición, los ánodos fueron producidos en la planta de ánodos ubicada en la Refinería de Cobre de Ilo. Ahora los ánodos son producidos directamente en la Fundición y como resultado, la composición química de los ánodos ha cambiado, principalmente en el contenido de bismuto, antimonio, plomo y zinc, siendo diferentes a los parámetros de diseño original de la Refinería. Asimismo, este factor impulsó a revisar el proceso de remoción de impurezas y los parámetros de la refinación electrolítica en la Refinería para evitar la contaminación del cobre refinado, logrando mantener la continuidad de la producción de cátodos de cobre de alta calidad superando los estándares interna-cionales de la norma ASTM-B115.

Sep 12, 2011

By J. O. Marsden

Over the past eight years, Phelps Dodge (a subsidiary of Freeport-McMoRan Copper & Gold, Inc.) devoted a significant amount of effort to the development of a suite of processes for the effective hydrometallurgical treatment of copper sulfide concentrates. This effort resulted in the development of high-temperature (>200ºC) and medium-temperature (150° to 165ºC) pressure leaching processes. Specific configurations of both processes have been commercially demonstrated at Phelps Dodge?s facility in Bagdad, Arizona. This paper reviews in detail the chemistry of medium-temperature pressure leaching of copper concentrates and reports on the process development work conducted by Phelps Dodge and others for this technology. This paper is Part I of a four-part series on this technology. Part II covers the development of medium-temperature pressure leaching and direct electrowinning technology; Part III considers the large-scale demonstration of the MT-DEW-SX process at Bagdad, Arizona; and Part IV addresses the development and design of a full-scale commercial application at Morenci, Arizona.

Jan 1, 2007

By John Folinsbee, Brian Danyliw, Tony Y. Chong

"Control of fugitive dust has become increasingly important in the mining industry both from a health and safety and environmental standpoint. Mining operations in particular have required improved fugitive dust control due to recent lowering of the allowable airborne silica concentration to which workers can be exposed. Experience has now proven that the implementation of a surfactant based chemical dust suppression system can enhance existing mechanical dust control methods resulting in much more efficient control of fugitive dust.The Porcupine Joint Venture (Dome Mine) utilizes dry secondary crushing and screening that makes it particularly prone to fugitive dust emissions. A variety of potential dust control systems were evaluated and this led to the installation of a surfactant based water spray system to augment the existing mechanical dust collection systems.A great deal was learned through the implementation of this system. This paper describes the entire process, from testing, system design and installation, through optimization and standardization of operation. In addition a variety of problems were identified, and innovative solutions were provided. Also, the metallurgical impacts on down stream processing are highlighted. Finally, a full discussion of overall results including a discussion of the relationship between silica and total dust concentrations is included."

Jan 1, 2005

By Sofoulis J

In the Archaean of the Kalgoorlie-Norseman area, the layered rocks have been subdivided into two sequences, both containing basic igneous rocks and sediments. The lower sequence is distinguished by the presence of acid volcanic flows and large acid sills. The upper sequence is unconformable on the lower one.In some areas, clastic sediments become coarser and pass into conglomerates. Th:s passage is accompanied by thinning of the beds.These features and their distribution suggest a basin of subsidence flanked by areas of shore-line conditions.Repeated igneous activity, including vulcanism, has occurred along the flanks of this basin. These different igneous and sedimentary environments have played an important part in the primary distribution of metals.A chronology of all basic and acid igneous activity, as well as sedimentat:on, has been established for the Precambrian of this area.INTRODUCTIONThe subdivision of Archaean rocks into those of basic igneous or of sedimentary origin has formed the basis for the nomenclature appearing in past literature. These subdivisions were distinguished as greenstones (predominantly basic igneous rocks) and whitestones (predominantly sediments), and it was generally accepted that the greenstones were stratigraphically lower in the sequence than the whitestones.Recent studies show that, between Kalgoorlie and Norseman, basic igneous rocks interfinger with and pass laterally to sediments, and that basic volcanic rocks occur at different stratigraphic levels. Younger Precambrian. units are also...

Jan 1, 1965

By W. W. Adams

"The seventh National Safety Competition, that for 1931, conducted by the United States Bureau of Mines, was participated in by 350 mines and quarries operating in 34 States. Tables 1 to 5 show the relative standing of the various plants, Bronze trophies, known as the ""Sentinels of Safety,"" which were provided by The Explosives Engineer magazine to be awarded annually by the Bureau of Mines were awarded to five companies, each company having established the best accident—prevention record within one of the five classes into which all companies were divided — namely, anthracite mining companies, bituminous—coal mining companies, metal—mining companies, operators of nonmetallic mineral mines other than coal mines, and quarries or open—cut mines. The trophies are awarded for one year and are then transferred to the winners of the succeeding year's contest.The outstanding feature of the contest of 1931 was the operation of a bituminous coal mine without a lost—time injury to any employee. While accident—tree records had previously been made by certain quarries, metal mines, and nonmetallic mineral mines, never before has such a feat been accomplished by a bituminous coal mine in the National Safety Competition. Whether or not such a record has been made by a bituminous—coal mining company not enrolled is the competition the writer does not know, but it is believed that the case referred to is unique among large coal—mining companies. The mine to which reference is made is No. 1 mine of the Phelps Dodge Corporation, at Dawson, N. Mex. To that company belongs the distinction not only of being the first coal—mining company among those enrolled in these yearly safety contents to operate its mine without an accident but also of occasioning the 'Sentinels of Safety' trophy for a bituminous mine to take its first journey west of the Mississippi River. For the past six years the trophy has been in West Virginia, Alabama, or Pennsylvania."

Jun 1, 1932

Research 86 highlights significant studies conducted during the past fiscal year at Bureau facilities and offices. Readers who want more information about the projects and studies summarized here can contact the researchers whose names and locations appear with each summary. General information on Bureau of Mines programs is available from the Office of Technical Information 2401 E Street, NW., Washington, DC 20241. A listing of principal officials, a location map of field facilities, and a selected bibliography of publications and patents issued on Bureau developments during the past 3 years are provided.

Jan 1, 1986

By D. F. Hambley

This manual contains a step-by-step procedure for the design of ore passes for open pit mines. The manual is comprehensive and deals with all aspects including location, design, construction and operating considerations. In the construction section, all applicable raising and shaft sinking methods are considered and cost estimates and advance rates provided for each. The design process is divided into several sections - rock flow requirements, support design, dump point design and draw point design. Use of this manual provides open pit planning engineers with a means of designing and assessing the feasibility of ore passes for their operations.

Jan 1, 1983

Alluvial gold grades are typically highly erratic. It is very often difficult to establish with confidence the in situ grades of reserve blocks due to the small number of pit or drill hole samples available, and their erratic values. Trends in grade are often obscure. Geostatical methods are inappropriate due to the extreme nugget effect found in alluvial gold field data. Classical statistics appear more suited to such data but require assumptions to be made regarding the nature of the population sampled. Recent developments in computer intensive non-parametric statistical methods provide a new approach to dealing with some of the above problems. These methods avoid making assumptions about the type of population distribution, usually through some kind of re-sampling scheme. The bootstrap procedure involves taking the estimate of interest and synthesising its population of by re-sampling the original data a large number of times (1000+), at random and with replacement. The synthetic population is then used to draw conclusions about the likely behaviour of the true population.

Jan 1, 1985

By Kausik M. Sinha

Hydraulic stowing, which is being practiced in several major coal producing countries to deal with adverse mining conditions, usually permits almost 100% coal recovery from underground mines with minimal and controlled surface subsidence. It can be implemented in the US coal mines to reduce the severe effect of land subsidence and at the same time improve the cost of coal production, both of which are major setbacks for the coal industry in the USA

Jan 1, 1989

By W. Barnett

The Limpopo Metamorphic Belt is a complex geological terrane with at least three major deformational events. Tectonically juxtaposed lithology, open to isoclinal folding, crosscutting and re-activated shear zones and metamorphic gneisses and schists make pit slope design and maintenance a risky business. Venetia diamond mine?s Cut 3 is planned to reach 360 m by 2011. The difficult rockmass created problems in the original pit and a new more comprehensive slope design was necessary. Nearly 9 km of geotechnical drilling were undertaken to produce a new geological model and provide geotechnical information near the final Cut 3 face. All existing data from the pit were brought together into a database. SRK Consulting were brought into the project to audit the process and provide most of the manpower for the data analysis. Existing failures were back-analysed and the geotechnical domains identified. Analyses of only the southern domains are discussed in this paper. Geotechnical engineers can design slopes at any angle, but it is up to the managers at the mine to decide what risk they are willing to accept in a slope design. Once the issue of risk was discussed and settled in respect of the consequences of failure, each of the main geotechnical domains were analysed to produce a slope design at5% probability of failure with 15% above the first ramp. A risk assessment of the design was then undertaken to determine what risk the design placed on the equipment, personnel and the profitability of the overall mining operation. The risk assessment indicated minimal risk to the operation. One of the main assumptions of the final design is that the pit slopes will be dewatered. A project was immediately put in place to determine a groundwater model for the mine and to thereby determine the best dewatering procedure. However, it should be obvious that it is practically impossible to prevent benches from getting briefly saturated with water during storm conditions. It was therefore necessary to look specifically at supporting the crests of the ramps in the problematic southern domains to guard against the possibility of crest failure during heavy rains. The data available were re-analysed toward this objective. Spiles were recommended as the most cost-effective support system, and a probabilistic approach was used in the design. The final design has a 5% probability of failure, and the analyses indicate a strong sensitivity of the required spile spacing to the strength of the reinforcement material that will eventually be used. The pit slope parameters derived as per the discussion in this paper have just begun to be implemented at Venetia Mine.

Jan 1, 2001

By R. H. Colquhoun

"INTRODUCTION The Holt-McDermott Mine is wholly-owned gold mining operation of American Barrick Resources Corp. that begun operations in June 1988.The property is located 0.5 km. south of Highway 101 East in the Harker-Holloway Townships of Northeastern Ontario, 7 miles south of Lake Abitibi and 15 miles west of the Quebec-Ontario border.Employees of the operation travel daily from various communities in the area, predominantly from Kirkland Lake, Ont., which is located 65 km. to the southwest.The significance of the operation is that it is the first full scale operation associated to the Oestor-Porcupine Fault to go into full production in recent history as well as the first Carbon-in-Leach (CIL) operation in the province owing to the natural occurring carbonaceous ores that are associated to the ore body and the geological fault systems.GEOLOGYThe Holt-McDermott deposit is located in the Abitibi Greenstone Belt, a short distance west of the Ontario-Quebec border. Ore grade material follows the footwall contact of a fault zone known locally as the McKenna Fault, which is thought to be a splay off of the Oestor-Porcupine Fault, itself a major feature in the Abitibi belt.The McKenna Fault strikes approximately east-west (as does the Oestor-Porcupine) and dips to the south at sixty-five to seventy degrees. The fault lies within a package of mafic volcanic rocks (basalts). These rocks have been strongly altered and mineralized adjacent to the McKenna Fault, and the resulting lens-like ore bodies constitute the mining targets."

Jan 1, 1989

In order to reach a large, untapped reserve of high-quality coal, D8 Cloverlick mine proposed to mine a corridor nearly 2,000 ft deep beneath the Benham Spur of Black Mountain, Kentucky’s highest peak. D8 Cloverlick mine was extracting the Owl seam, but the corridor’s route lay approximately 70 ft above century-old mine workings in the C–(Darby) seam. Adding to the concern, three serious coal bursts had recently occurred in nearby Owl seam workings.

Jan 7, 2020

By R. W. Heins, N. Street

An investigation was made of the Rehbinder-Kuznetsov pendulum as an instrument to aid in the study of rock drillability and of the effect of surface active agents on rock drillability. The "critical weight", i.e., the pendulum weight at greatest sensitivity, was determined for several solids and it was shown that a change in surface environment changed the maximum value of the apparent hardness but not the critical weight, and the critical weight increased with increase of hardness of the solid used. Using silver halides as the solid material, and solutions of either silver nitrate or the appropriate alkali halide, it was shown that there is a hardness maximum at the zero point of charge of the particular silver halide. INTRODUCTION The development of relative hardness measurement by the method of damped oscillations, or what has been called the pendulum sclerometer, is due largely to the Russian workers P. A. Rehbinder and V. D. Kuznetsov and their co-workers.1,2 The apparent simplicity of the method has led to its use in a number of fields, particularly those where relative hardness has to be determined on a brittle solid. As will be shown, the simplicity of the method belies its complexities. THEORY OF THE PENDULUM SCLEROMETER The operation of the pendulum is quite simple. Make a sharp point such as a diamond, hardened steel or tungsten carbide, as the fulcrum of a pendulum, with the center of gravity of the system below the point of support. The attenuation of this pendulum is a function only of air friction, provided no fragmentation, breakage or other work is performed by the point. However, when the solid surface breaks or disintegrates under the point, and the latter penetrates the solid, part of the energy of oscillation is absorbed in the work of creating new surface, and the rate of attenuation increases. In the case of brittle solids, the point of the pendulum produces fragmentary particles, whereas the point produces plastic deformation in a plastic solid; but in both cases damping occurs. This pendulum damping is a function of the hardness or strength of the solid. Whereas a pendulum oscillating on a hard material attenuates primarily by air friction, in the case of a soft material, the points penetrate the surface of the solid, producing new surface, and the pendulum damps much faster. Thus the attenuation rate is a function of the hardness or strength of a material in both plastic and brittle substances. Russian workers initially used a single support for the pendulum, but this created many problems because of oscillation of the pendulum in more than one plane. A revised version used two points, or sometimes a prism as support, successfully confining oscillation to one plane. The version using two points was constructed and used throughout this investigation, making the recording of the attenuation as a function of time relatively easy. That both points should be in contact with the solid during the damping is implied. Rehbinder (c.f. Kuznetsov2) proposed that the hardness H as measured by this method could be expressed by a quantity which is inversely proportional to the relative initial rate of attenuation of amplitude. where H = hardness parameter (arbitrary units) a, = initial amplitude da/dt = rate of attenuation of amplitude with time. In the simplest case of damping with a constant logarithmic decrement, H can be regarded as a constant for the duration of the whole damped oscillation process. That is

Jan 1, 1966