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By James L. Vinson

Wilbur Smith Associates (WSA) has provided planning, engineering and construction oversight assistance to the Tennessee Department of Transportation (TDOT) for three construction projects intended to widen and improve segments of I-40 and associated interchanges in Knoxville, Tennessee. The projects are within the karst terrain of the Valley and Ridge Province. Subsurface conditions are characterized by an irregular rock surface coupled with differential weathering. Because of the projects? impact to local and interstate motorists, consideration was given to innovative planning, materials and construction practices that could accelerate construction. Two innovative deep foundation measures included rock-socketed pipe piles, which act as both foundations and substructure elements for a bridge?s interior bents, and the first widespread use of rock-socketed drilled shafts as bridge foundations on a TDOT project. The pipe piles were used at a site with significant cavities within the limestone bedrock. This resulted in design verification and constructability difficulties that required delays, but measures were ultimately employed to produce a sound foundation system. Over 110 drilled shafts have been constructed at sites with generally low solution activity. Relative to H-pile footings, which were included as an alternate foundation, they have apparently allowed accelerated construction at a competitive cost.

Jan 1, 2006

By P. G. Claridge, G. P. Holmes, M. A. Redfearn

"IntroductionThe purpose of this chapter is to describe current practices in operation and maintenance of flotation circuits in Canadian mineral processing plants. The chapter consists of five sections covering description of equipment, typical flow diagrams, operating practice, instrumentation and maintenance. The approach to this subject matter is intended to be practical in nature, hence no deeply technical treatment of flotation theory will be included.Flotation is an extremely common method of beneficiation of ores. Reasons are the relatively low cost of flotation compared to many other processes, the wide range of minerals to which flotation may be applied and the high efficiency of separation which can usually be achieved. The flotation process as we know it today has been developed within this century and it has had a major impact on the mining industry. While flotation is commonly considered to be important because it provides a relatively simple method of separating minerals in complex ores, the availability of flotation has also made a multitude of mineral deposits in Canada into economically viable mining operations because it allowed production of a concentrate of valuable minerals from the ore. These concentrates could then be transported from geographically remote locations to centraHzed plants for further processing, although the existence of the remote and perhaps small ore body alone would not have justified installation of metallurgical processing plants on site and the grade of ore would not have justified direct shipment of ore.Some of the more common minerals concentrated by flotation are sulphides of copper, nickel, cobalt, iron, zinc, molybdenum, lead and arsenic, as well as non-sulphides such as sodium chloride, potassium chloride, phosphates, silicates, chromite, fluorite, limestone and coal. Precious metals are also recovered by flotation, generally in association with another sulphide mineral."

Jan 1, 1989

By J. Tanner Blackburn, James R. Gingery, Lisheng Shao

Rigid inclusions consist of grout columns installed using displacement auger or vibrated tooling. The columns are typically installed in an array to provide support for footings, mats, or embankments. Due to the relative small column diameter and low replacement ratio, the surrounding soils typically have minimal densification or improvement. A gravel load transfer platform is commonly used above the rigid inclusion head to distribute stresses more broadly to the supported structure. The axial stiffness and geotechnical engineering mechanics of rigid inclusion design are similar to those of deep foundation systems, but they are typically only lightly- or un-reinforced and are not structurally connected to the above-grade structure. The popularity of rigid inclusions is increasing in the Western U.S., where many urban areas are subject to moderate to high seismic hazard levels. However, the performance of rigid inclusions under seismic loading is poorly understood, and seldom addressed in current designs. The elements are brittle, with limited or no ductility and relatively low moment capacity, and therefore may be prone to damage under seismic loading. Three modes of seismic loading should be considered: inertial loading from the structure, kinematic loading from vertically propagating shear waves, and kinematic loading from ground failure- related permanent ground deformation. This paper focuses on the first two modes. A simplified procedure for evaluating kinematic and inertial loading of rigid inclusions is described, and its use is illustrated through application to a site in Southern California. The results show that moderate to severe kinematic loading can generate plastic hinges in the rigid inclusions. Engineering consequences of this hinging could include settlement or bearing failure. INTRODUCTION In this paper the term ‘rigid inclusion’ (RI) refers to grout or grouted aggregate columns that are installed using either drilled or vibration displacement techniques. They are commonly installed in arrays to support vertical loads from footings, mats, or embankments. RIs are not structurally connected to footings they support. Rather, it is typical for a dense gravel load transfer platform (LTP) to be installed as a cushion between the RI head and supported footing or new fill. In cases of RI support of fill embankments, the LTP may be reinforced with horizontal layers of geogrid.

Jan 1, 2018

By M. S. Fleming

The objective was to evaluate central lubrication systems for potential use on underground mining equipment. Previous use on continuous mining equipment resulted in poor system performance because of improper selection of lubricants, component failures, and an inconsistent delivery of lubricant to the bearings. The principles and operational characteristics of systems are reviewed and evaluated, and it was concluded that systems are available which can provide reliable central lubrication if properly applied, installed, and maintained. The procedures for applying a system to a continuous miner are discussed. Investigation revealed the lack of significant information on lubrication-related equipment failures and injuries related to maintenance and repair operations, the lack of significant failure rate data for central lubrication system components, and the lack of performance standards for central lubrication systems and components. To continue the development of systems for underground mining equipment it is recommended that a data bank on failures and reliability for equipment with and without central lubrication systems be created, and standardized specifications and performance criteria be developed for central lubrication systems and components which will be used on underground mining equipment.

Jan 1, 1979

By S C. Dominy

Various styles of gold mineralisation pose problems during sampling because of their complex gold grade distribution and presence of coarse gold. Effective sampling and sample preparation forms the basis of resource estimates. The design of a sampling and assaying protocol must be based on a thorough understanding of the mineralisation in question, which should include consideration of gold particle size and mass distribution. The proportion of coarse gold within samples has a profound effect on the requirements for sample preparation and assaying. Choice of preparation procedure and assay type is of critical importance if sampling errors are to be minimised. Traditional fire assays, using small charge sizes, often understate assays gained from large charge sizes and techniques such as screen fire assay and LeachWELL. Proper application of the Theory of Sampling reduces errors during collection, preparation and assaying. A quality control/quality assurance program must be implemented and critically assessed. A case study from the Ballarat mine is presented, which is characterised by substantial quantities of coarse-gold hosted in quartz veins. Diamond core drilling is the key input into resource delineation. A number of different sampling and assay options have been trialled over the recent project history. The current sampling protocol utilises whole drill core, using LeachWELL assays after logging and photography.CITATION:Dominy, S C, 2017. Sampling coarse gold-bearing mineralisation – developing effective protocols and a case study from the Ballarat mine, Australia, in Proceedings Eighth World Conference on Sampling and Blending , pp 71–84 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

There are many ways to classify structural slurry wall elements, but the DFI committee chooses to limit these descriptions to three functional requirements, namely: design function, plan configuration and type of panel reinforcement. (See Figure 1 in Part IV for panel classification). Slurry walls can function as: 1. Curvilinear or linear elements for temporary and/or permanent structures to resist lateral forces transferred from the ground, water, earthquakes and various surcharge loads. 2. Load bearing elements in various plan shapes to resist vertical forces. 3. Combination Elements to resist combined forces under conditions 1 and/or 2. For example, elliptical shafts with various openings for tunnels and conduits have been commonly used for deep excavations.

Jan 1, 2005

By E Rojas, C Pardo

The exploitation of primary ores using cave mining caused new challenges at the El Teniente mine that required changes to a number of conventional cave mining practices. For example, in the 1970s and 1980s, panel caving was introduced to manage certain geotechnical and operational conditions. Today, El Teniente mine is facing new challenges associated with deep cave mining and establishing its New Mine Level (NML) project, which is located 240 m below the Esmeralda operating cave.The engineering and development phases for this new project have been largely based on experience and lessons learned throughout the history of primary ore exploitation at El Teniente mine, particularly knowledge about seismicity control, the management of collapses and operational practices. For example, previous experience demonstrated that seismicity could be managed by preconditioning using large-scale hydraulic fracturing (HF). HF has been systematically applied in the column of ore above the undercut planned for the NML project and below the production or extraction level, where the main ventilation and haulage infrastructure are to be located.This paper discusses how this has been achieved and is based on previous experience of preconditioning using HF, which has been applied in the selection and management of exploitation techniques and associated planning strategies and design parameters for the NML project.CITATION:Pardo, C and Rojas, E, 2016. Selection of exploitation method based on the experience of hydraulic fracture techniques at the El Teniente Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 97–104 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Leonardo Zuchi Guio

A ArcelorMittal Tubarão vem trabalhando continuamente no aumento de produção de seu Laminador de Tiras a Quente (LTQ). Com o aumento da produção, o risco de colisão de material ao longo do LTQ, com maior possibilidade de ocorrência na mesa de resfriamento de tiras, se elevou. De forma a permitir aumento de produção e evitar colisão de material, desde o início de 2016 iniciou-se um trabalho de ajuste no modelo. Dado que o modelo consiste na determinação do ritmo de laminação a partir da liberação de extração de placas dos fornos, início do processo de laminação, o trabalho envolveu a criação de um ponto de controle de ritmo no meio da linha do laminador. Para suportar um controle adequado nesse ponto, foram necessários ajustes de parâmetros e cálculos para aumento da precisão do modelo. Esse trabalho apresenta os ajustes realizados para utilização do novo ponto de controle, bem como os ajustes realizados para aumento da precisão do modelo e os ganhos de produtividade obtidos a partir desses ajustes.

Oct 30, 2017

By J. Wade Watkins, Joseph W. Horne, Arthur Matzick

"A successful procedure for the recovery of a valuable product from weathered tank-bottom settlings has been developed in the laboratories of the Bureau of lines and used in a field pilot plant. These heavy emulsion settlings, generally regarded by the industry as waste material, have usually been drained into open pits or storage ponds and eventually destroyed.Laboratory examination of the waste material shows it to consist essentially of a ""water-in-oil"" emulsion containing a considerable volume of congealed ""paraffin."" This paraffin is mainly high-melting-point wax; known in the industry as microcrystalline wax, for which there is an increasing demand.Because of the physical properties of this wax, the tank-bottom settlings are not responsive to conventional methods used for demulsifying ordinary crude-oil emulsions.The work upon which this report is based was conducted by the Bureau of Mines in cooperation with -the Kansas State. Board of Health and with special cooperative agreements-with the Cities Service Oil Co, Bartlesville, Okla., and the Bareco Oil Co,. Barnsdall, Okla. The studies were made under the general supervision of R. A. Cattell, chief engineer, Petroleum and Natural-Gas Division, Bureau of Mines, Washington; D. C., and H. C. Fowler, supervising engineer, Petroleum Experiment Station, Bureau of Mines, Bartlesville, Okla., and under the direct supervision of Ludwig Schmidt, senior petroleum engineer, Bureau of Mines, Bartlesville, Okla.Gratefully acknowledged are the assistance and cooperation given by the Cities Service Oil Co. of Oklahoma and especially by M. J. Kirwan, manager of production, and by Q. E. Beecher, general superintendent of production, Bartlesville, Okla., and to members of their staff at Oil Hill, Kans.The assistance and suggestions of V. R. Oakley, general superintendent, E. R. Wiles, director of research, L. G. Willis, field engineer in charge crude-oil supply, and Gerald DeWalt, chief chemist, and his staff of the Bareco Oil Co., Barnsdall, Okla., were of much value in the laboratory and recovery work."

Mar 1, 1946

By Q Zhuo, P C. Pistorius, M N. Al-Harbi

A likely increasingly important pathway for future low-carbon ironmaking and steelmaking is the combination of gas-based direct reduction with electric furnace steelmaking (DRI-EAF route), or with electric smelting (DRI-ESF route). In the DRI-EAF route, the gangue that is present in the iron ore is fluxed and removed as slag in the melting (steelmaking) step. This is in contrast with integrated steelmaking, in which the gangue is removed as part of blast furnace ironmaking. For DRI-EAF steelmaking, the amount and composition of slag depend on the iron ore composition, flux additions and iron yield. Slag volume and composition affect phosphorus removal, foaming behaviour and the process energy requirements. In this work, heat data from a year of DRI-EAF production was analysed to test whether the expected relationship between slag volume and electricity consumption for EAF steelmaking was observed. The data include slag analyses (one sample per shift), and heatlevel information on all inputs, final steel temperature and dissolved oxygen concentration, electricity consumption, tapped steel mass and tap-to-tap time. In analysing the data, the slag volume was estimated from the assayed slag CaO concentration and CaO inputs to the EAF. The expected effect of slag volume on steelmaking energy consumption was calculated with a mass and energy balance, considering the heat of mixing of the slag. The calculated energy requirement of slag formation is in line with previous estimates reported in the literature.

Aug 21, 2024

By Z. G. Li

The large-scale vibrating screen has been applied widely in coal industry and other industrial areas as a kind of important device. As vibration mechanical device, it works very hardly and works in very bad environment so that the structure of screen is damaged easily. Therefore, it is very important that how to detect the fault of structure as early as possible to make the repair schedule reasonably and economically and to avoid the body hurt and device damage. As a kind of important structure of vibrating screen, the lower crossbeam is the main carrying structure and it is easily damaged, so it is regarded as a researched object in this thesis and it is tested under the load in the laboratory. Based on the test, acoustic emission wave signals can be got-ten by modern acoustic emission testing technique. Then, the ?wavelet packet - energy? from the characteristics of acquiring signals is used as neural network input vector. In the BP network structure design, the design of a hidden layer with variable number of BP network is established. Based on the error by contrast, the best nerve number can be identified in the hidden layer. Through integrated analysis, using Levenberg-Marquard BP study algorithm, network-training errors are relatively small, the acoustic emission signal is used in BP neural network as a pattern of recognition. In Matlab6.5, neural network model identification is created and taking advantage of nonlinearity and the ability of learning and memory of Neural Network, this model is fixed by training structure of network with training samples. The work presented shows that acoustical emission signal processing and research on early fatigue fault diagnosis based on the wavelet and the neural network is viable.

Jan 1, 2014

By E. Shekarchi

A year after the Soviet Union invaded Afghanistan and replaced President Amin with their choice, President Karmal, Afghanistan remained in turmoil. In some respects, the political and economic situation in Afghanistan was no better by the end of 1980 than it was preceding the December 1979 invasion. The Government faced widespread and growing alienation and resistance, virulent factionalism within the ruling party, and an acute shortage of material. The mining sector of the country did not fare better either; the only raw material produced in a significant amount was natural gas, which was exported mainly to the Soviet Union. No statistics on production of other minerals and materials were available by yearend. Most of Afghanistan's gas production was from the Hodja-Gugerdag Field, southeast of Shibarghan. The gas flow from this field had been about 300 million cubic feet per day since 1961. An estimated 230 to 250 million cubic feet per day of Hodja-Gugerdag's production was moved by pipeline across the Amu-Darya River into the Soviet Union. Most of the remainder was transmitted eastward to a 105,000-ton-per-year fertilizer plant and an electric power station built near Mazar-i-Sharif with Soviet assistance. After the Soviet invasion, the second gasfield, Djar-Kuduk, in the Shibarghan area, was brought under production. This field, which will produce about 200 million cubic feet per day, consists of four gas zones in the Jurassic and lower Cretaceous zones between 3,000 and 8.500 feet deep. The gas has a high hydrogen sulfide content, with considerable carbon dioxide, A new treatment plant was built at Djar-Kuduk by Soviet technicians under a turnkey contract at the end of 1980. It is believed that most of the Djar-Kuduk's initial flow will be sent to the Soviet Union.

Jan 1, 1982

Geologists in some underground gold mines collect grab samples from broken ore piles or trucks as a method of grade control. It is often known as muck sampling. Generally, the goal of grab sampling is to try and reconcile the mined grade at the ore source to the predicted grade and/or predict the mill feed grade. The mass of the sample collected is limited by health and safety issues, as well as by the capacity of the laboratory to process the samples within a given time frame. In general terms, grab sampling is known to be problematic because samplers tend to oversample the fines, and/or pick out high-grade fragments; surface sampling of piles does not test material within the pile; muck piles in development drives/faces are likely to be zoned due to the blasting sequence; high or low-grade material may preferentially segregate in the pile during mucking; the five per cent mass reject size of the material in muck piles is very large from underground blasting; some correlation usually exists whereby the larger fragments are enriched or depleted in the critical component of value; and the average error made in estimating the true stockpile grade is likely to be high. The method is prone to chronic fundamental sampling, grouping and segregation, delimitation, and extraction errors. Substantial warnings must be given about the use of grab sampling for grade control in gold mines. The method may appear to work sometimes, which can be attributed to a fine gold particle sizing and more disseminated distribution. As with all sampling methods, its appropriateness must be determined by ore characterization and heterogeneity testing to ensure the method suits the ore type.

Jan 1, 2010

By Jeffrey S. Walker

The purpose of this U.S. Bureau of Mines effort was to determine if ground movement caused by mining-induced subsidence is directly transferred to a structure and, if so, how that transfer takes place. Four concrete block walls with foundations were constructed and monitored over an active longwall panel. Three of the walls were located perpendicular to the direction of mining in zones where maximum inclination, maximum tension, and maximum curvature were predicted to occur. The fourth wall was constructed along the centerline of the panel, parallel to the direction of mining. All of the walls and the surrounding ground surface were instrumented with conventional survey monitoring points and extensometer stations to observe the vertical and horizontal movements. The fourth wall instrumentation also included continuously recording tiltmeters. The results of this investigation indicate that these simple structures respond to subsidence in a similar manner as the ground surface. This suggests that once the transfer mechanism is more fully defined, prediction models can be developed to accurately estimate the effect of mining on surface structures.

Jan 1, 1989

The Federal Coal Mine Health and Safety Act of 1969 limits to 2 milligrams per cubic meter (for dust containing a maximum of 5% quartz) the average respirable dust concentration to which individual miners may be exposed. Section 205 of the Act directs that an appropriate exposure formula for dusts with quartz content in excess of 5% be established. This formula, entered in F. R. Document 70-12351 filed September 16, 1970, is 10 milligrams per cubic meter divided by % quartz. Thus, the total respirable dust exposure permitted limits the quartz to a maximum of 100 micrograms. For example, if % quartz is 5%, 10 mg/5 = 2 milligrams, and (.05) (2 mg) = 100 micrograms. Similarly, if % quartz is 10%, 10/10 = 1, and (.10) (1 mg) = 100 micrograms, etc. If the % quartz is less than 5%, the 2 mg/M3 limit prevails.

Jan 1, 1974

By C A. Locke, M Stevens, P Vidanovich, J Cassidy, J L. Mauk

The Karangahake adularia-sericite epithermal gold-silver deposit, located at the southern end of the Waitekauri Corridor, Hauraki Goldfield, occurs as quartz veins with associated alteration haloes. Integrated geophysical studies were undertaken to determine the expression, location, and extent of these alteration zones. Aeromagnetic data show an extensive, magnetic æquietÆ zone over Karangahake and the southern Rahu Ridge that represents a zone of magnetite destruction resulting from hydrothermal alteration. Analytic signal data are used to define the boundary of this zone; the resulting 6 km2 area is elongate north-south with an irregular boundary. A detailed gravity survey over the area reveals a positive residual gravity anomaly, up to 30 gu in amplitude, over the Karangahake deposit. Density measurements on near-surface rocks give low values indicating that the source of this positive gravity anomaly must be deep; possible causative bodies include an igneous intrusion or dense sulfide mineralisation. To the west and east of the host Waipupu Formation, strong gravity gradients of 100 gu/km and 65 gu/km reflect the faulted boundary of the Hauraki Rift, and the edge of the Waihi Basin respectively. High resolution airborne radiometric data define a 2.2 km2 area of potassium enrichment. This area is elongate north-south and has an irregular boundary. It coincides approximately with the centre of the magnetic quiet zone and the peak of the gravity high, and correlates with known areas of intense mineralisation. Anomalously high potassium counts and elevated K/Th ratios correlate with areas of potassic alteration that have undergone K-metasomatism. Underexplored portions of this zone may indicate areas of gold-silver prospectivity. Combined geophysical data therefore reveal the extent of hydrothermal alteration, and the central zone of Kmetasomatism that is most likely to contain orebodies.

Jan 1, 2005

By P. A. Hacquebard, M. P. Avery

"Gondwana coal deposits are widespread and are known to occur in four continents. They are present in Brazil, India, South Africa, and Australia. From coal petrographic examinations and a detailed literature survey, it is interpreted that Gondwana coals are present also in Canada and the United States. Laurasia, or Northern Hemisphere, coals occur in the United States, Canada, and Europe. They form the main coal producing fields of the world. Megascopically, Gondwana coals have a uniform, micro-banded appearance, with a dull lustre; Laurasian coals are bright and have distinct bands of vitrain and clarain. Petrographically, Gondwana coals, compared to Laurasian coals, are lower in vitrinite, but higher in inertinite, particularly in semifusinite. Mineral matter averages 16% in Gondwana coals and 5.7% in Northern Hemisphere coals.Gondwana coals are characterized by thick seams that terminate through lithification (Versteinerung), whereby coal passes laterally into shale. Laurasian coal seams are thinner and terminate by splitting and digitation.Vitrinite/inertinite ratio data indicate deposition of the Gondwana coals in dry marshes under strong oxidizing conditions. The Laurasian coals originated in wet marshes in a reducing environment. As deduced from fossil plants and fossil spores, temperate and near arctic conditions apply for the Gondwana coals. A tropical and subtropical climate is indicated for the Laurasian deposits. The Gondwana coals were formed under allochthonous conditions. They derived from vegetation that drifted into the peat bogs. The Laurasian coals are autochthonous and originated from vegetation that grew and was buried in the peat bogs. The Gondwana coals are Late Carboniferous and Early Permian. The Laurasian coals are entirely Late Carboniferous."

Jan 1, 2004

Under contract from U. S. Bureau of Mines, Harza Engineering Company in cooperation with Eastern Associated Coal Corporation, conducted a ground control study of two mechanized longwall panels at the Federal Number 2 Mine. The mine is located in Northern West Virginia, and the coal is mined from the Pittsburgh Coal Seam. The prime objective of the study was to collect data which will aid in the proper selection of the longwall supports system and to control the entry caving problem. Instruments installed in the mine were borehole pressure cells, convergence recorders, roof sag recorders, horizontal roof strain indicators, differential floor movement systems, and lateral roof and floor movement systems. Instruments installed on the surface, above the instrumented longwall panels, consisted of slope indicator system, vertical bed settlement probe system and shear displacement detecting system. A comprehensive surface subsidence study was conducted in conjunction with the instrumentation. In addition to the instrumentation and monitoring, special tests were conducted to determine the bearing capacity of the roof and floor rocks, in situ modulus of coal, roof and floor rocks, and response of borehole pressure cells to ground stress. Cores of coal measure rocks were collected for the physical property tests. Face observations were made to detect various roof behavior parameters under the different jack setting pressures. This report essentially describes the instrumentation work, special tests and presents the data collected.

Jan 1, 1976

Preliminary work being undertaken on the optimisation of decision strategies for an open-pit metalliferous deposit is presented. The Optimal Control method has been selected rather than the easier to implement Dynamic Programming method of optimisation since a fundamental criteria of Dynamic Programming is violated. Essentially a system of state equations and decision variables is developed for the operation under consideration.

Jan 1, 1984

By V. Balakrishnan, A. Hewitson

"The Kudremukh Iron Ore Company Limited, a government of India enterprise, has constructed iron ore mining, crushing, handling and concentrator facilities at Kudremukh, in southwest India. Concentrate produced is pumped 65 km to dewatering, storage and ship-loading facilities which were built at the same time at the sea port of Mangalore.A computer-based distributed process control system was implemented for all operations at Kudremukh and to interface with and monitor the Mangalore plant.The control system is examined from various standpoints, beginning with a description of its architecture, method of process input/output connection, and major hardware items.Software considerations and process applications are then looked at, with a review of the integration of the computer vendor's system software with user-developed applications programming. A control example of crusher operations is provided.Following the descriptive segment is a discussion of the design considerations and decision factors involved in the implementation of such a system considering the type of process and the remote nature of the installation site. It ends with a review of actual operating experience and conclusions regarding both this system and future similar applications.ScopeThe following is a discussion of the computer-based process control system applied for the Kudremukh Iron are Company Limited's ore handling, concentrating and shipping facilities located in South India.A general description of the process and plant equipment will be followed by an examination of the control system from the points of view of hardware and signal flow, software requirements, design considerations, implementation logistics and operating experience. Conclusions will be drawn concerning this and future computer applications."

Jan 1, 1984