Search Documents

By N. Loganathan, Tan Boon Tee, Joe O’Carroll, Richard Flanagan

In recent years, tunnelling activities in Singapore have increased considerably with the construction of extensions to the existing sub-surface transport system, a deep tunnel sewerage disposal system, and tunnels for the laying power cables and other utilities. These tunnels are excavated through urban areas, adjacent to high-rise buildings, depressed road structures, beneath other tunnels, and buried services. Earth pressure balance (EPB) tunnel boring machines (TBM) have been used extensively in Singapore with great success. The risk associated with soft ground tunnelling, including tunnelling through Old Alluvium, can be minimized with an understanding of the geology, geotechnical parameters, and the tunnelling-induced behaviour of Old Alluvium (OA The purpose of this paper is to present some design and construction aspects of EPB TBM tunnelling through Old Alluvium.

Jan 1, 2005

By D. F. Boyd

On April 10, 1958 a new 7500 long ton/day iron ore beneficiation plant went on stream producing an average of 3000 long-tons of high quality concentrate a day. Plant operates on two, 12-hour shifts is six days per week, The new mill end crust ink plant were built adjacent to the company's open pit dining operate on at Bomi Hills, Liberia. The mall is essentially a gravity concentrator employing crushing, and grinding to liberate the mineral values, followed by concentration in Humphreys spirals. The cleaner spiral tailings are re-ground and tabled to recover additional iron values. Ire addition to. this mills the company operates a crushing and screening plant for the high grade direct shipping ores

Jan 1, 1962

By Brad Simser

Several case histories from Glencore’s Sudbury Operations show how passive seismic monitoring data is used for geotechnical decision making. The data comes from three different seismic arrays monitoring two open stoping deposits, and a narrow vein cut and fill/blasthole operation. Mining depths range between 1000 to 1680m below surface. The deposits are hosted in hard igneous rocks typical of the Sudbury basin, with characteristically high horizontal stress (approximately 1.8 times the depth of overburden). Rockbursting is the main geotechnical risk, due to the strong brittle nature of the rock and local high mining extraction. Fault related seismicity includes both fault slip events, and the stress channelling effect as the mining front approaches a major fault structure. Planar data trends generally line up with known faults and often indicate early stage fault activation. The structures are risk ranked based on their seismic response. This has been particularly useful at the Nickel Rim South Mine (NRS) where the structural fabric (jointing and small-scale faulting) is generally parallel to the more through going faults. The persistence of structures is difficult to measure, and the NRS faults generally have low offsets and thin gouge. The visual difference between the more persistent structures that occasionally generate large seismic events (up Mw 2.9 to date) and localised joints/slips is often minor. The seismic monitoring data clearly shows the more active structures. This information is highlighted on mine plans to help guide enhanced ground support and seismic re-entry protocol barricade locations. Pillar loading/yielding is a key element to the blasthole operations where a primary/secondary mining sequence is used. The secondary pillars are mined in a yielded state with just-in-time development. An example of the seismic signature of a secondary stope is shown with emphasis on the need for high location accuracy given the stope widths of 12.5 to 15m. The ratio of the shear wave energy to primary wave energy (Es/Ep) has long been used as a method to estimate source mechanisms; the higher the ratio, the more likely the event is fault slip versus rock fracturing. Data sets are filtered on Es/Ep ratios to highlight both fault slip populations and stress fracturing mechanisms. Examples of seismic data quality checks, high stress development, and re-entry protocols are also shown in the case histories.

Apr 26, 2022

bauma 2004 will feature a couple of firsts for one of the world’s largest construction and building materials machinery exhibitions. The event is scheduled for March 29 through April 4 of next year at the New Munich Trade Fair Center in Munich, Germany. For the first time, bauma will feature an exhibition area dedicated to mining equipment and technology. Also for the first time, the Commonwealth of Independent States (CIS) will be a partner region of bauma.

Jan 1, 2003

By R. Dorey

The Kennecott Ridgeway Mine in South Carolina is scheduled to complete mining and ore processing in the last quarter of 1999. Tailings are disposed in a 300 acre, lined tailings impoundment. To facilitate closure and reclamation, modification of the tailings impoundment operation has been adopted. Mining involved the sequenced development of two open pits. In 1996 mining of the South Pit was completed and backfilling of the pit with waste rock from the North Pit was initiated and will continue until mining ceases. Both pits will be reclaimed as fresh water lakes. This paper presents the physical, geochemical and hydrogeochemical evaluation of the operational and post operational management of the project. Comparison of the operational monitoring data against predicted performance is reviewed.

Jan 1, 1999

By Josh Swank

Albert Einstein once said, ?the important thing is not to stop questioning.? In the mining industry, a lack of inquisitiveness may lead to a blissful ignorance but it certainly will not increase efficiencies. While one may claim necessity is the mother of invention, questioning and analyzing how methods and systems can be improved is the catalyst to discovering necessities. Understandably, when working in the middle of Canada?s oil sands, where trucks operate around the clock every day of the year, it is nearly impossible to pull the nose from the grindstone long enough to provide thorough analysis. But, fortunately, some manufacturers/inventors have assisted by examining the process and the ensuing headaches within this application.

Jan 1, 2013

By Jr. Schnakenberg

The automation (robotization) of coal mining activities at the face offers improvements in worker safety and productivity. The evolutionary introduction of autonomous, intelligent robotic machines to perform the most hazardous tasks may become a reality within the next 10 years. The U.S. Bureau of Mines Robotics and Automation research program is aggressively pursuing the development of the enabling technology necessary to achieve this goal. This program consists of both core and applications research, each focused on the fundamental issues of robotic technology. In the short term, the research is directed specifically to the robotization of present-day underground equipment and is being performed in a manner that can make incremental improvements in safety and productivity. The long-term goal is the development of intelligent autonomous mining systems.

Jan 1, 1990

By M. J. Shulman

An algorithm used by the US Coast Guard to find lost objects is utilized to optimally allocate exploration efforts during initial stages of an exploration program. Based on classical search theory, the algorithm assumes a target probability distribution function, a detection func¬tion, and a cost function. The three Junctions are analogous to delineating areas of possible mineralization, choice of exploration methods, and exploration budget. Application of the algorithm is shown for a hypothetical target distribution. Using the maximum number of field days available as the cost function, the optimal allocation of effort is shown for different exploration methods, e.g. electromagnetic survey and induced polarization. The adaption of the algorithm for the exploration process is discussed.

Jan 3, 1984

By S. M. Cohen

Roll crushers had been used in the past ahead of existing milling systems in order to obtain additional production from such mills in both the mining and the cement industries. Historically, a roll crusher as a preliminator to a ball mill has been used for a number of industrial mineral applications. Flowsheets, from Taggars(1) show systems for fluorspar, graphite, lead and zinc to name a few, which are shown in Figures 1 to 4. These units applied, (in some cases still in service), prior to 1950 and as early as the 1920's, were of two general types, rigid rolls and spring rolls. The rigid rolls were phased out in favor of the spring rolls. The spring force related to the linear inch width of the rolls, ranged from 500 to 50,000 lbs/linear inch(1) on units up to 90" diameter. With choke feeding, the rolls were spread against the spring force during crushing keeping the system under high pressure to obtain high effectiveness.

Jan 1, 1986

By B. Govindarajan, T. C. Rao, J. P. Barnwal

A simple modelling methodology has been proposed to predict the performance of industrial coal flotation circuit based on the observations made on the actual performance. The solid content in the tailings of the coal flotation circuit has been identified as a lode-star to predict the performance in terms of yield and ash content of the concentrate. The modelling parameters are directly measurable.

Jan 1, 1995

By O. Akinkugbe

The safe, productive exploitation of coal in multiple-seam situations requires specific design technology. At present, there are two general design approaches that the mining engineer can use to analyze the multiple-seam problem in question, either simple empirical relationships or complex numerical models. Often, the empirical approaches are too general for the specific problem and the numerical models require too much time and expertise for the practicing engineer. In this paper, a new program designed for quickly and easily calculating the stresses, strains, and safety factors associated with basic multiple-seam mining situations is presented. The program implements a simplified, two-dimensional boundary-element method in order to model the complex multiple-seam stress and displacement interactions. The program incorporates automatic coal and gob property generation to simplify the input, and inherently calculates pillar safety factors to enhance the output.

Jan 1, 2004

By Yukika Miyashita, Takahiro Inoue, Kenji Namikawa, Masashi Matsumoto, Junichi Koseki, Yoshihiro Terashima

"In order to construct an underground two-layer expressway branch junction structure with a height of 14.7 m and a width of 22.3 m, two shield tunnels in each layer were combined by using a non-cut-and-cover enlargement method in sedimentary soft rock. Before and during the construction work, preliminary analysis, in-situ investigations and laboratory tests were conducted to ensure the construction safety and to evaluate the deformation characteristics of sedimentary soft rock. The construction project was safely executed without any water leakage or collapse of tunnel working face. The predicted results from preliminary analysis were almost similar to the measured values. From the detailed investigation of measured results, it was confirmed that the deformation characteristic of the sedimentary soft rock was observed to a small extent as the ground deformation derived from construction work. INTRODUCTION In recent years, some newly constructed urban expressways in Japan are being planned as underground structures due to the consideration of roadside environment. The construction of such underground expressways is frequently conducted using a shield tunneling, a typical one of non-cut-and-cover methods, to prevent any adverse effect to traffic in arterial roads, operation of nearby commercial establishments, and daily lives of local residents during construction work. For underground urban expressway, the connections with existing road network on ground surface or on elevated sections are indispensable, which require the construction of an underground branch junction with large cross-section. This raises a technical difficulty regardless of the open-cut or non-open-cut construction method."

Jan 1, 2016

By Charles Merguerian

In medium- to high-grade metamorphic terrains such as found in New York City(NYC), rock mass texture and mineralogy are important factors in predicting TBM penetration destiny. Integration of data from over two decades of traditional field and tunnel mapping suggest that hard-rock TBM penetration in the NYC area depends upon textural, mineralogic, and structural control. The bedrock of NYC consists of many different lithologic units of varying age, composition, texture, and metamorphic grade including many varieties of intrusive rock. In addition, brittle faults of numerous orientations cut the polydeformed crystalline bedrock, producing zones of highly fractured and disturbed ground and high water inflows. Pre-bid compilation of published bedrock data, drill core analysis by geologists to establish lithologic and mineralogic trends, integrated surface geologic mapping along a proposed alignment, and targeted petrographic and geotechnical investigations to characterize the rock mass conditions together constitute an important prelude to successful subsurface bidding and tunneling. A carefully planned program of as-built geological mapping, structural analysis, fracture class mapping, and monitoring of machine performance data provide important information for adjusting to changed conditions. In complex terrains, a clear understanding of the structural geology of any proposed tunnel line is the simplest and most cost-effective method to mitigate losses encountered during TBM tunneling.

Jan 1, 2005

By Paul R. Smith

The Colorado School of Mines Research Institute (CSMRI) was founded in 1949 to fill mining industry and government needs for minerals research and development. The operations of scores of mines, mills, and plants around the world are based on the results of work done by the Research Institute. Among other things, the Research Institute conducts studies in geology, mine planning, mineralogy, size reduction, minerals processing, and hydrometallurgical techniques in extractive metallurgy. Many CSMRI projects also involve energy and environmental considerations. What follows is a summary of some of the studies in which the Research Institute has been and is currently involved, as well as some comments on trends and developments in the industry.

Jan 2, 1982

By Chao Zhang, Wenhao Xia, Jianxin Fu, Ling Yu, Weidong Song, Yang Li

Sanshandao Gold Mine is the only undersea metal mine in China. To deal with the collapse and pumping of stopes and roadways caused by complex ore-rock occurrence conditions, the mine conducts filling and sealing of some areas, and the remaining ore reserves will be mined after treatment. Therefore, it is urgent to evaluate the stability of rock masses, fault fracture zones, and aquicludes during the secondary mining process. In this study, displacement and microseismic methods are employed to monitor rock deformation and fractures. Additionally, FLAC3D was used to simulate the process of secondary mining, reproducing the evolution of stress fields, displacement fields, seepage fields, and plastic zones at different mining stages. The combination of numerical simulation and on-site monitoring verification demonstrates that the deformation of surrounding rock presents a rapid growth at the initial stage of mining, followed by a gradual decrease in the growth rate, and finally tends to stabilize; the fracture zone area at the 151–159 exploration line on the − 320 m level (near the 7# and 8# stopes) exhibits poor stability, and monitoring measures should be strengthened; the deformation value of the aquiclude is less than the deformation value of I protection level in the Code for Design, the impact of secondary mining on the aquiclude is limited; fault and fracture zone deteriorate rock mass stability, and their impact is related to their spatial locations. Hanging wall fault has a more significant impact on the settlement of the aquiclude, while the footwall fracture zone has a greater impact on the development of the plastic zone.

Feb 21, 2024

By P. A. Plunkert, D. E. Morse, L. McCartan, S. F. Sibley

The average annual growth rate of real gross domes-tic product (GDP) from the third quarter of 2001through the second quarter of 2003 in the United States was about 2.6 percent. GDP growth rates in the third and fourth quarters of 2003 were about 8 percent and 4 percent, respectively. Many other indicators reflected a rebounding U.S. economy — rising consumer confidence, higher retail sales, greater industrial production and more housing starts. Inflation also reached a 38-year low in 2003. The upward trends in many sectors of the U.S. economy in 2003, however, were shared by few of the mineral materials industries. Annual output declined inmost non fuel mining and mineral processing industries, although there was an upward turn toward yearend as prices began to increase (Table 1).

Jan 1, 2004

By K. Short

Over the past several years, the mining and minerals market was overloaded with discussions around reviving mature terminologies like distributed control systems (DCS), programmable logic controllers (PLC), and the ?new comers?: hybrid control systems (HCS) and programmable automation controllers (PAC) and, in parallel, which technologies would be more appropriate for mining and mineral processing applications. Ten years ago, a careful comparative analysis would make more sense. Control approaches had very distinctive differences where users needed to choose the right approach.

Jan 1, 2012

By M. A. A. de Klaver

Functional Description Figure 1 is a typical flowsheet for a system for solid fuel addition to filter cake. Solid fuel, coal, coal breeze, or charcoal, is fed from a,stockpile to a surge hopper. The solid fuel is metered into a grinding mill. The fuel is dried and ground in a grinding mill. The on-size particles are removed from the mill by air sweeping. The ground solid fuel is separated from the air stream by a cyclone and stored in a surge hopper. The ground solid fuel is then pneumatically conveyed to a small hopper in the balling area. The fuel is proportioned into the filter cake just prior to mixing. An efficient mixer is very important to have a successful operation. The exact flowsheet would depend on a number of factors including what fuel is used, how the fuel is received, and the cnaracteristics of the fuel as received. Availability of floor space in the plant may also affect the flowsheet. For example, drying air may be supplied from the pellet furnace if the grinding mill can be located near the grate, or the pneumatic conveying system and a surge hopper may be eliminated by placing the grinding mill adjacent .to the mixing area. Also, for a multiple line plant, a ball mill rather than a roller mill may be more suitable.

Jan 1, 1980

By G. Barbery

In Mineral Processing, the objective of most processes is the separation of mixtures of minerals, which are originally associated in composite particles. Feed preparation processes grinding for instance, which take place before beneficiation or separation processes do not usually break particles at the boundary between mineral phases. They produce composite ("middlings") as well as liberated particle. It is therefore necessary, in a particulate system, to determine the proportion of particles which are liberated as well as, ideally, the size distribution of minerals which remain associated in composite particles. Up to now, there has been a lack of experimental techniques to characterize completely composite particulate systems. Heavy liquid separation which is commonly used to obtain information of this type can only be applied to simple binary cases for which one mineral has a low density (lower than e.g 2.8 ). The technique which is proposed in this paper involves the measurement of parameters on polished sections of particles mounted in a matrix, and the use of mathematical transformations to reconstruct in three-dimensions the information obtained from these measurements .

Jan 1, 1977

By D. Z. Mraz, R. S. Jones

Unlike in coal mines where caving methods are used, the subsidence over potash mines in Saskatchewan, Canada, is a function of gradual mining convergence. Because of the presence of high pressure water aquifers over the evaporite salt formations, the mines have to be designed as regionally stable and no caving is allowed. The extracted area converges gradually and the convergence is mainly a function of the extraction and the mining method employed. Consequently, the subsidence rate is very slow and the bridging of the over-lying strata is a considerably more important phenomenon than elsewhere. The paper evaluates a case history of convergence and subsidence in a deep potash mine in Saskatchewan.

Jan 1, 1986