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By C. Sun

The Leeville underground mine has been in operation since 2006 and currently produces 3,500 tons of ore per day with an average gold grade of 0.34 opt. The mine has a large horizontal extent of 2,500 feet by 500 feet and a vertical extent of 20 to 200 feet. Based on the characteristics of the ore bodies, a long-hole stope and cut-and-fill mining methods are used at the deposits which are divided into several mining zones. Cemented rock fill (CRF) is used as the backfill in the open stope. CRF design includes the aggregate design, the ratio of cement and fly ash design, and strengths for the long-hole stope and cut-and-fill. In the aggregate design, the particle size distribution is one of the most influential aggregate characteristics in determining how it will perform as a basic backfill material. Gradation helps determine durability, porosity, cement and water requirements, strength, and shrinkage. To cut the backfill cost, fly ash usually is added into the binder to replace some part of cement. However, adding fly ash can affect the strength of the backfill. The reasonable percentage of fly ash is also important for making a good and low cost backfill. Based on the different mining method, the different backfill with different strength is designed. A systematic quality control procedure for aggregate and backfill is followed. After four yeas application, CRF system in Leeville achieved very good results.

Jan 1, 2011

By Pedro Hugo Tumialán

El método de los isovalores metálicos para estudiar el zoneamiento de las vetas ha sido utilizado desde 1967 en el Perú. Sin embargo, dicho método no permite precisar la posición relativa de un elemento métalico respecto al otro, cuyos cocientes metálicos se han estudiado. En ese sentido, el presente texto señala el método del logaritmo de dichos cocientes metálicos, el cual se puede aplicar cuando se dispone de análisis por tres o más elementos, graficando la posición de logaritmo de cocientes metálicos de las leyes de los bloques de cubicación en un sistema de coordenadas en el que cada eje corresponde al logaritmo de un cociente métalico dado. Una vez conocido los zoneamientos relativos se podrá graficar las curvas de los isovalores de los cocientes metálicos de la estructura mineralizada a través del proceso matemático.

Sep 1, 1983

By Christopher J. Bise

INTRODUCTION The transportation of men, supplies, and mined material from an underground operation is the connecting link between the mine plant and the surface plant. Unless the mine is accessed by a drift or adit, some form of hoisting system is necessary for slopes or shafts. This chapter will deal with the selection of wire ropes and hoists, two of the most important consider¬ations when designing a hoisting system for an under¬ground mine. WIRE ROPES General A wire rope is designed to transmit forces longitudi¬nally along its axis. Wire rope is used in a variety of mining applications because of its flexibility, high ten¬sile strength, and dependability. Shaft hoisting ropes and principal slope haulage ropes are usually custom-¬built; however, proper rope selection for slushers, car spotters, etc. should not be overlooked. Wire ropes for shafts and slopes, since they represent the life line for the mines, should be of the very highest quality improved plow steel. This quality is necessary to deal with the conditions of loading, winding, vibration, abrasion, and corrosion. Tables I and 2 display the specifications for the typical wire ropes used for mine haulage applications. The 6 x 19-class haulage rope is used for most hoisting where abrasion is not critical. On the other hand, where abrasion is critical, such as a slope application, 6 X 7-class haulage ropes are preferred. For other mining applications, manufactur¬ers' handbooks should be consulted. Selection The selection of a wire rope for a mining situation consists of simply applying appropriate safety factors to a calculated maximum rope pull and comparing the result to the listed breaking strength of the rope under consideration. Table 3 can be used for determin¬ing the minimum factors of safety for wire ropes. To determine the maximum rope pull, the following quantities must be known: the rope weight in pounds (x), the conveyance weight in pounds (y), and the weight in pounds of the load in the conveyance (z). These values are used to calculate the load due to gravity, the load due to conveyance friction, and the load due to rope friction. When these loads are added together, as shown in Eq. 1, the maximum (static) rope pull (RPS) can be derived:

Jan 1, 1986

By K. M. Phamotse, A. S. Nhleko

"*Paper written on project work carried out in partial fulfilment of BSc (Mining Engineering) degreeSynopsisLiqhobong Mining Development Company (LMDC) has been experiencing problems with boulders after blasting where the fragment sizes exceed the maximum of 800 mm as per mine standard. As a result, the mine has employed various methods to improve the fragmentation. The goal is to produce a run-of-mine (ROM) feed that does not choke the crusher and cause delays in production. In order to achieve this goal, fragmentation distribution within the fines and coarse envelope must be optimized through effective planning of blasting activities and accurate execution.The mine determined the fines-coarse envelope within which the entire crushing system can handle fragments using Split Desktop software. It is expected that both the predicted and actual fragmentation curves lie within that envelope for optimal fragmentation. The Kuz-Ram model with blast design parameters of 2.6 m for burden, 2.8 m for spacing, and 127 mm hole diameter was used to predict the fragmentation. The results show that the blast design parameters may need altering to achieve optimum fragmentation. Furthermore, the execution of the drilling and blasting may be the cause of the fragmentation problems. The mean fragmentation size (X50) differs greatly, unlike the uniformity index (n)s values which are relatively close to each other (0.6 to 2.2). The mean squared error (MSE) values have a large range. A proposed solution is a modified burden, spacing, and hole diameter. It is concluded that blast design parameters need to be reviewed in order to obtain correct predictions. IntroductionFragmentation has an impact on the mine production cycle which comprises, inter alia, drilling, blasting, loading, hauling, and crushing. Correct fragmentation as set by the plant design is important as it reduces the time lost due to secondary blasting and/or loading difficulties. In this paper we analyse blast results at Liqhobong Mining Development Company (LMDC) in Lesotho for a period of six months. This project was undertaken to observe the trends from the blasts and to identify whether any discrepancies exist in the overall blast information. The period under study included 16 blasts."

Jul 1, 2019

By C. Erichsen, J. Werfling

ABSTRACT: A three-dimensional elastic constitutive model for rock salt is proposed. This stress strain law takes into account the three phases of creep (transient, steady state and accelerated creep), dilatancy, as well as the failure and post failure behaviour. The model was implemented into a finite element program and validated on the results of laboratory tests and in situ measurements. A good qualitative and quantitative agreement with the test and measurement results is achieved. A stability analysis for an underground repository in rock salt is presented. ZUSAMMENFASSUNG: Es wird ein dreidimensionales elastisch-viskoplastisches Stoffgesetz für Steinsalz vorgestellt. Mit diesem Stoffgesetz können die drei Kriechphasen (primäres, sekundäres und tertiäres Kriechen), Dilatanz sowie das Bruch- und Nachbruchverhalten erfaßt werden. Dieses Modell wurde in ein Rechenprogramm, das auf der Methode der finiten Elemente basiert, implementiert und an Ergebnissen von Laborversuchen und in-situ-Messungen validiert. Die Versuchs- und Meßergebnisse lassen sich mit diesem Stoffgesetz qualitativ und quantitativ gut nachvollziehen. Als Anwendungsbeispiel wird der Standsicherheitsnachweis für eine Untertagedeponie im Steinsalz erläutert. RÉSUMÉ: Cet article présente un modéle constitutive élastique/viscoplastique à trois dimensions pour sel gemme. Ce modéle comprend les trois stade de fluage (fluage primaire, secondaire et tertiaire), la dilatation, le comportement de défaillance et d'après défaillance. Il est implanté dans un programme de calcul aux éléments finis. À l'aide des essais laboratoire et des mésures in situ, le modéle a été validé. Les résultats des essais et des mesures concordent qualitatifs et quantitatifs aux résultats des calculations.

Jan 1, 2003

By H. K. Lin

Deepwater discharges of sulfide flotation tailings have been practiced for several decades. Oxygen penetration and organic matter content in such environments are the two major factors that determine their reduction-oxidation condition and hence the rate of sulfide mineral dissolution under such discharge environments. In this study, the effects of solution redox potential and pH on the dissolution of some heavy metals from sulfide flotation tailings were examined. Zn, Pb and Cu concentrations in solution were all higher at a higher redox potential and lower pH. Dissolved Zn concentrations reached 100 ppm even at a low redox potential of 105 mV and near neutral pH after 33 days. Pb concentrations were below 2 ppm at 105 mV and near neutral pH after 165 days. At 105 mV, the Cu concentrations were below 0.2 ppm at near neutral pH after 165 days. At pH 2.3, the Fe concentrations were higher at 420 mV than at 105 mV. But at pH 6.8, the Fe concentrations were lower at 420 mV than at 105 mV, due to the oxidation of Fe2+ to Fe3+ and the subsequent precipitation of ferric hydroxide. Arsenic concentrations in solution were all less than 0.002 ppm. For Zn, Cu and Fe, no significant differences were observed between the tests in solutions prepared using seawater and those using distilled water. However, Pb concentrations reached higher levels in solutions prepared using seawater.

Jan 1, 2009

By S. Klein, D. Crouthamel, D. W. Farmer, S. H. Phillips

Groundwater inflows during construction pose one of the greatest risks to the successful completion of tunnel projects. Inflows can result in safety concerns, difficulty in mining and ground support, impact sensitive environmental habitats, create surface settlement and increase costs. Adequately planned pre-excavation grouting programs benefit both the Owner and Contractor in reducing risks and controlling project costs and potential schedule delays. This paper outlines strategic guidelines for assessment of site conditions for pre-excavation grouting hard rock tunnels. It also describes the design of pre-excavation grouting programs with respect to project requirements.

Jan 1, 2005

By Hugo Vásquez Rosas

El presente texto señala la composición química de un mineral de cobre a través de un estudio microscópico. El estudio consiste en establecer los componentes químicos del mineral por medio de las microfotografías con luz reflejada normal. Estos componentes son la bornita, chalcopirita, chalcocita, hematita y cuarzo. De acuerdo a los estudios efectuados por Schwartz, la bornita y la chalcopirita forman extensas pero no continuas soluciones sólidas a temperaturas elevadas -por encima de 475°C. dado que tienen como componentes los mismos elementos y la estructura cristalina es parecida.

Nov 1, 1954

This Bureau of Mines publication consists of an overview of the mine waste management research currently being conducted by the Bureau. The following papers, given at a Technology Transfer Workshop, emphasize the increasing importance of research related to the safety and environmental considerations of mine waste disposal In recent years. Current work related to legislation passed in the last 10 years and their subsequent standards includes the development of adequate monitoring systems, development of stability and seepage prediction and control techniques, control of runoff water, and control of leaching solutions. Selected topics are included here that cover coal mine waste disposal, embankment slope stability monitoring, flow failures of mine tailings impoundments, and controlled burnout of abandoned coal mine fires. The projects described provide a current documentation of problems being addressed.

Jan 1, 1981

By Phillip R. Mulligan, Kevin Gantz, Aaron J. Ward, allen shirley, Sean Treadway

Understanding the impulse transferred into a structure by the coupled two-phase loading produced by an explosive charge buried in soil is of interest for various applications. The most common impulse measurement technique involves a buried explosive charge and a steel plate/test structure suspended above the charge. Upon detonation of the charge, the soil and overpressure heave the plate into the air. The plate’s trajectory and velocity provide the necessary information to calculate the total impulse transferred from the charge configuration.

Jan 1, 2016

By F. N. Kissell, C. M. McCulloch, Maurice Deul, J. R. Levine

The methane content of virgin bituminous coalbed can now be measured accurately in the field with exploration core samples from vertical boreholes. The gas content of the coal per unit weight can be used either to design a mine ventilation system or to determine if degasification of the coalbed will be necessary before mining, and to determine the gas resources in the coalbed. The equipment necessary to conduct the test costs less than $50. The gas content of the coal in place in the ground is determined by summing the gas lost from coring, gas measured during desorption, and the residual gas in the coal. Upon removal from the borehole, the core sample is placed in an airtight container and desorbed for several weeks until the desorption rate is below 0.05 cm3/g for 5 consecutive days. The gas lost from the core while it was being cored and the residual gas are estimated by a new graphical method. The amount of gas remaining depends upon whether the coal is friable or blocky. Friability appears to relate to the depth of the sample below the surface, fixed carbon percentage, Hardgrove grindability index, and proximity to tectonic disturbance. Friable coals emit nearly 96 pct of the total gas during desorption whereas a blocky coal emits only 60 pct of its total gas. Coalbeds that are ill defined as to their blocky or friable nature must be tested in the laboratory for unambiguous analysis.

Jan 1, 1975

By Carlos Filippe de Sousa Morais

O software desenvolvido tem como objetivo, mapear o real tempo de operação do RH da Companhia Siderúrgica Nacional - CSN, identificando os atrasos antes e durante o tratamento de um aço no equipamento. Para isso foi criada uma tela automática que é aberta ao operador toda vez que é identificado atrasos, seja durante a troca de panela (Disponibilidade) ou durante o tratamento do aço (Processo). É possível visualizar em qualquer período desejado o preenchimento dos atrasos através de um relatório e uma interface gráfica interativa gerada pelo software, e com isso tomar medidas capazes de melhorar a produtividade no RH. Os resultados abordados ao longo deste trabalho mostram que a solução de uma pequena parte destes atrasos pode gerar ganhos de produção significativos para a Companhia Siderúrgica Nacional.

Aug 16, 2017

By Braden Lusk, Tristan Worsey, Nathan Rouse, Kyle Hall

Loading explosives up hole has challenges that are typically not seen in down hole explosive loading. Most explosives applications are not up hole. Lack of experience and technology can cause significant problems when loading explosives up hole. When results aren’t achieved, the blame is commonly put on the design when the true problems are unknown. Not knowing the cause of the problem causes drill and blast designs to be over engineered and very costly with little success. Being able to know and record key data is crucial to actually solving the problem. This paper goes over blast instrumentation that can be used to trouble shoot drill and blast problems in up hole explosives loading in underground mines. The tools and procedures used to trouble shoot include velocity of detonation recorder, borehole tracking, seismographs, and borehole camera. Each item will be discussed in detail with a case study to show the usefulness of the instrumentation. The operation discussed in the case study had issues pulling raises and had hang ups in the stope shots. These problems caused production slowdowns and costly remediation blasting that was not very successful. The case study is an underground gold mine that used modified sub-level caving with backfill as the mining method.

Jan 1, 2018

By John R. Reynolds

This paper describes mining and milling methods of the American Smelting & Refining Co. at the Morning mine in the Mullan area of the Coeur d'Alene mining region in Idaho and is one of a series of Bureau of Mines reports dealing with methods and costs of mining throughout the United States. The Morning mine has been described previously in a Bureau of Mines report published in 1930,2/ and the milling methods and costs at the Morning concentrator were presented in a Bureau of Mines report published in 1932. 3/ These reports are supplemented by this publication, which presents data to show the effect of changing times and conditions on a typical medium-size mining operation during the latter part of its history, when costs were rising and production was from increasingly greater depths. The report contrasts two periods in the history of the mine-periods not too far separated in years but considerably different in economic conditions. During the first period (1939) costs of labor and materials were moderate, mining operations were just being transferred from the main shaft to deeper workings opened from the offset shaft, and the operation prospered. During the second period (12 years later) production costs had increased following the national trend in all industry, mining was from greater depths near the bottom of the ore body, and the operation was becoming unprofitable. Mining on the lower levels of the property ceased in 1953.

Jan 1, 1956

By Nick D. Rose

Outline ?Background ?History of inverse-velocity for failure prediction ?Methodolog ?Case Histories ?Three case examples of predicted slopefailure to actual date of occurrence ?One case example of mitigated slope failure using inverse-velocity to forecast failure time and schedule remedial measures ?Conclusions

May 1, 2006

"INTRODUCTION Industrial utilization of the present submarginal domestic manganese resources of the United States is wholely dependent at this time on the electrolytic manganese process established as the result of 4 years of continuous operation of the Bureau of Mines pilot plant at Boulder City and 7 years' operations of the Electro Manganese Corporation commercial plant at Knoxville, Tenn.Three Kids ore provided the feed for the Boulder City pilot plant during 3 years of operation. Hence, the electrowinning characteristics of the ore have been thoroughly established, making possible accurate estimates for commercial operations.Before the Defense Plant Corporation constructed the leaching plant, the Bureau of Mines conducted an exploration project to determine the extent and grade of the ore reserves. Additional exploration, development, and mining by the Manganese Ore Cc, have accurately determined the tonnage and grade of ore. A large tonnage of stock piled ore is now available for immediate processing, and a considerable tonnage of openpit ore has been stripped of overburden preparatory to mining. Numerous facilities, such as power, water, and housing, needed for an electrolytic manganese plant are already available.All of these factors, as well as plans for installation of scale electrolytic manganese plant facilities, are presented in detail in the chapter entitled, ""Mining and. Electrolytic Reduction of use from Three Kids Manganese Mine."" The Manganese Ore Co. kindly provided information on the present ore reserves and state of development of the mine."

Jun 1, 1945

By Victor Hugo Pereira Moraes e Oliveira

A indústria petrolífera demanda tubos com resistência mecânica e tenacidade à fratura cada vez maiores. Estas propriedades, determinadas pela microestrutura, são modificadas completamente na soldagem. Este trabalho avaliou a formação de constituinte MA na ZAC de grãos grosseiros, reaquecidas ou não intercriticamente, de junta de topo circunferencial para tubos de aço API 5L X100 desenvolvido para águas profundas. Simularam-se com elementos finitos e em sistema Gleeble ciclos térmicos de soldagem com diferentes aportes de calor para processo FCAW. Foram feitas análises com microscopia ótica e eletrônica de varredura, além de medidas de microdureza. A morfologia do constituinte MA, cuja fração foi maior nas simulações com o maior e o menor aporte de calor e mínima para o aporte de 2,0 kJ/mm, foi muito alterada pela temperatura máxima simulada. A simulação da soldagem mostrou ser bastante complexa, e vários fatores críticos que afetam a tenacidade das juntas soldadas foram analisados por meio de simulação computacional.

Oct 30, 2017

By Nelson Severinghaus

Mineral fillers have been defined as inert materials that are included in a composition for some useful purpose. Because this definition and the scope of this review are not specific- indeed, exceptions abound-accurate total statistics are unavailable. One source estimates the total production in the United States in 1971 at 5 million tons valued at $200 million, averaging $40.00 per ton. Included are a broad group of minerals-asbestos, barite, bentonite, calcium carbonate, clays, diatomite, feldspar, micas, silica, talc. Additional references will be made to synthetic mineral-derived fillers such as aluminum hydrate, precipitated calcium carbonate, and pyrogenic and precipitated silicas and silicates. A section on related uses at the end of this chapter covers absorbents and filters. Mineral fillers can be included in compounds to accomplish a variety of final results. Hardness, brittleness, impact strength, compressive strength, softening point, fire resistance, surface smoothness, electrical conductivity, and a host of other physical characteristics may be modified by the inclusion of fillers. These effects are the result of properties of the fillers, including chemical activity, hardness, particle size, shape and distribution, surface structure, color, density, and refractive index. To facilitate an overview of the mineral filler industry, this chapter will review the general usage of fillers, the inherent characteristics that intensify their utilization, and similarly their manufactured characteristics. Major using industries will then be examined in detail. Specific information on deposits and processing for industrial minerals will be found in the appropriate commodity chapter. The chart in Table 1, updated from the 3rd edition of Industrial Rocks and Minerals, illustrates the major mineral fillers (both natural and manufactured) and their more important end uses.

Jan 1, 1975

By Bernard Dallaire, Jean Cayouette, Sylvain Duchesne

"Louvicourt Mine's concentrator, located near Val d'Or, Quebec, treats an average of 4,300 tonnes of ore per day composed mainly of copper, zinc, gold and silver. An analysis of concentrator revenues and metallurgical losses shows a potential for additional gain, particularly in regards to precious metals (kustelite) where recovery is usually around 67 -70 %. The planning, installation and trial operational period of two Outokumpu SK-240 flash cells at the underflow of the primary cyclones took two years. The use of (( flash flotation )) technology has made it possible to exploit the favourable conditions at the underflow of the primary cyclones such as precious metal concentration and the presence of liberated coarse chalcopyrite. These conditions permit early flotation (fresh surfaces) of the kustelite and the liberated copper. Since the start-up of the flash cells, the metallurgical gains have turned out to be very positive with increases in metal recovery reflected in appreciable NSR gains. Also, significant savings in reagent consumption and a coarser copper concentrate have made it possible to reduce the drying cycle of the Larox filter presses since the cells were put into operation.BACKGROUNDLouvicourt Mine is operated by Aur Resources Inc. (30% ownership) on behalf of its partners Novicourt Inc. (45%, subsidiary of Noranda Inc.) and Teck Corp. (25%). The mine is located in northwestern Quebec about 600 km north of Montreal and about 25 km east of the mining town of Val d'Or. The mine commenced commercial production in July 1994.The massive sulphide ore deposit lies at depths varying between 450 m and 900 m. Mining reserves (2% Cu equi. cut-off) as of Jan. Is', 2000 are estimated at 7.5 million tonnes of ore averaging 3.4% Cu, 1.8% Zn, 28.0 g/t Ag and 0.9 g/t Au. Delineated ore reserves permit the use of a mechanized transverse blasthole mining method. The extraction order is a typical 1.3.5 mining sequence. Primary and secondary stopes are 15 m wide, 15 to 70 m long (25 m long average) and 30 m high. Backfilling for pillar recovery and regional stability is required."

Jan 1, 2001

By H. L. Riley

At the Southern Experiment Station, Tuscaloosa, Ala., reports are prepared from time to time on results of washability studies of coal from important beds in the Southern Appalachian region. The investigations that provide the material for these reports are made by the Bureau of Mines, United States Department of the Interior, in cooperation with the University of Alabama and the mine operators. The principal objective of a washability study is to obtain technically and commercially important data to aid in determining the best methods for preparing and utilizing the Nation's reserves, particularly of coking coals. Such information is also important from the standpoint of conservation, because it facilitates the selection of preparation methods that will yield an acceptable product with a minimum loss of coal to the rejects.

Jan 1, 1958