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By William Gleason

Despite a global slowdown in most mining sectors, Caterpillar, the world?s largest mining equipment maker continues to forge ahead with new, and improved offerings to the global mining industry. On Nov. 10, as part of its Loading and Hauling Mining Focus Session at its Tinaja Hills proving grounds south of Tucson, AZ, Caterpillar unveiled to customers and media its two latest mining products, the 994K wheel loader and 6020B hydraulic shovel. The Caterpillar 994K wheel loader builds on a nearly 25-year history of the 994 model but with one noticeable difference ? the 994K is bigger ? much bigger. Weighing in at 239,142 kg (527,218 lb) the 994 K is up to 20 percent larger and comes with up to 30 percent increase in payload capacity. This behemoth of a machine is currently being tested at Caterpillar?s Tucson Proving Grounds, Anglo Gold Ashanti?s Cripple Creek and Victor gold mine in Colorado and Taseko?s Gibraltor copper and molybdenum mine in British Columbia, Canada.

M.S. Azun I have many objections to the content of the author's paper. Before discussing it, however, I would like to repeat the property of semivariogram function. Second order stationary properties of regionalized variables (ReV's) such as semivariogram function y(h) are perfectly known in geostatistics. Also, the kriging equations in the language of mathematical statistics using second order stationary properties are well understood. However, the way to use the sample (estimated) semivariogram function in any one of the kriging procedures is vague. The sample semivariogram function is given as follows: [ ] where N is the total number of samples, Xi is the sample value at the i - th location, Xi+h is the sample value at the i + h - th location, and h is the distance among the samples. An estimation variance of sample semivariogram function of first lag is smaller than that of higher order lag. The theoretical semivariogram function reaches the variance of samples asymptotically. But this is not easily observable because of the larger variation involved in the estimate of semivariogram function. In general, an estimation procedure is done for h = 0, 1, 2, up to the greatest integer less than N/2, even though sample semivariogram function can be computable through N-1. After estimating semivariogram function, the critical question of how to model sample semivariogram function arises. As seen in the above equation, sample semivariogram function is discrete and can be smoothed by the model being selected. Therefore, modeling of sample semivariogram function is the most important step in geostatistics. It not only smoothes a discrete function but also affects the results of the kriging procedure. When the only aim is to model the semivariogram function, which is the basic point of the author's paper, one can employ any fitting techniques, such as curve fitting, or any arbitrary functions, which are called submodels in the paper. The term "arbitrary function" is used rather than "submodel" because there is no basic understanding of developing them. The author suggests that the sum of those submodels can also be used for the modeling of sample semivariogram function. The combination of any arbitrary functions brings many problems instead of giving an insight of the domain structure considered. The author used two arbitrary functions and the nugget effect in response to sample semivariogram function (Fig. 10). For the same example, he stated that the parameters involved in the mixed arbitrary function model can be accepted when the discrepancy between sample semivariogram function and the model is small visually. For verifying the fitting behavior of any selected model, one should not be contented with the visual satisfactory. Some statistical measure such as goodness of fit has to be used. The author's practice is no more than an exercise in curve fitting without any fundamental understanding or conceptualization of the underlying physical mechanism. Furthermore, the selection of any model is not an easy task if the purpose is the search for the "best" response to the observed second order properties of ReV's. I suggest that the Markovian model (Azun, 1983), on the basis of a theoretical understanding of underlying mechanism, which gives more information about the occurrence of regionalized variables, is used to respond all properties of ReV's. There are a lot of problems for modeling of one-dimensional sample semivariogram function. Thus, it is not appropriate to go to higher order dimensional sample semivariogram function modeling. In the meantime, I would recommend that one can connect the values of standardized sample semivariogram function rather than simple values of semivariogram function in the two-dimensional estimation. The standardized values can be computed in dividing the semivariogram function value by the number of sample pairs involved in each lag regardless of the directions. In conclusion, geostatistics is an interdisciplinary area in mining that uses the principles of mathematical statistics. Thus, it should not violate any probabilistic and statistical rules. When Matheron was developing the theory of geostatistical study in the early years of geostatistics, many mining people had a reservation accepting the geostatistical tools. However, this does not mean that we, the geostatisticians, might try to convince those people using some "strange" tools or rules as some authors implied (Baafi and Kim, 1984). Instead, we have to develop and explain the geostatistical tools staying only in the framework of statistical concepts and properties. References Azun, M.S., 1983, "Stochastic Process Modeling of Spatially Distributed Geostatistical Data," Columbia University, Ph.D. Thesis. Baafi, E.Y., and Kim, Y.C., 1984, "Discussion - Comparison of Different Ore Reserve Estimation Methods Using Conditional Simulation," Mining Engineering, Vol. 36, No. 3, p. 280. Reply by J.M. Rendu The interactive method proposed by Rendu allows practitioners to develop semivariogram models that take into account not only the numerical information obtained by sampling, but also highly significant additional information that often cannot be quantified. The geology of the deposit - including hypotheses concerning its genesis, sampling methods, assaying methods, and mathematical methods used to calculate the semivariograms - all have an influence on the numerical results obtained and on how these results should be interpreted. If all the information concerning the spatial distribution of values in a mineral deposit was contained in the sample values, it could be argued that statistical techniques alone would produce optimum models. However, this is rarely, if ever, the case. Methods that allow the user to take into account his experience and his geologic understanding of the deposit should not be rejected for the sake of theoretical statistical purity.

Jan 11, 1985

By Paul F. Ziemkiewicz, Aaron Noble, Christopher R. Vass

The conventional rare earth element (REE) industry has historically sought to develop ore deposits where geologic processes have produced mineralized zones with commercially attractive REE concentrations. These deposits are extremely uncommon, particularly in the USA. Given the criticality of these materials and the need for sustainable domestic supply, the current research seeks to leverage other autogenous processes that lead to concentrated REE resources. One such process is the generation of acid mine drainage (AMD). AMD is very common in many coal mining districts and results from the exposure and oxidation of pyrite during mining. During the generation and migration of AMD, liberated sulfuric acid mobilizes several metal ions including REEs. Treatment of AMD is required under U.S.C §1251, the Clean Water Act, and often consists of neutralization, oxidation, and metal hydroxide precipitation. To investigate the deportment of REEs during this process, a field sampling campaign was undertaken, whereby the concentration of REEs in AMD and AMD precipitates was measured directly. In the nine sites evaluated in this study, the REE concentrations of the precipitates varied from 29 to 1286 ppm with an average of 517 ppm among the sampled sites. The individual elements were enriched compared with the associated bulk Northern Appalachian (NAPP) coal material by factors ranging from 3 to 15. Furthermore, the distribution of REEs in all precipitate samples favored the heavy REEs (HREEs) when compared with traditional REE ores. This research represents the first part of multi-part research endeavor to characterize, classify, and determine the practicality of refining REEs from AMD and its by-products.

By Paul F. Ziemkiewicz, Aaron Noble, Christopher R. Vass

The conventional rare earth element (REE) industry has historically sought to develop ore deposits where geologic processes have produced mineralized zones with commercially attractive REE concentrations. These deposits are extremely uncommon, particularly in the USA. Given the criticality of these materials and the need for sustainable domestic supply, the current research seeks to leverage other autogenous processes that lead to concentrated REE resources. One such process is the generation of acid mine drainage (AMD). AMD is very common in many coal mining districts and results from the exposure and oxidation of pyrite during mining. During the generation and migration of AMD, liberated sulfuric acid mobilizes several metal ions including REEs. Treatment of AMD is required under U.S.C §1251, the Clean Water Act, and often consists of neutralization, oxidation, and metal hydroxide precipitation. To investigate the deportment of REEs during this process, a field sampling campaign was undertaken, whereby the concentration of REEs in AMD and AMD precipitates was measured directly. In the nine sites evaluated in this study, the REE concentrations of the precipitates varied from 29 to 1286 ppm with an average of 517 ppm among the sampled sites. The individual elements were enriched compared with the associated bulk Northern Appalachian (NAPP) coal material by factors ranging from 3 to 15. Furthermore, the distribution of REEs in all precipitate samples favored the heavy REEs (HREEs) when compared with traditional REE ores. This research represents the first part of multi-part research endeavor to characterize, classify, and determine the practicality of refining REEs from AMD and its by-products.

If it had not been for the almost unbelievable adventures that came before and after, the last ten months of 19 15 would have been exciting enough for anyone. As it was they were a cheerful interlude. I spent most of the time on our Warren operations catching up on a lot of underground work and visiting Ajo every few weeks to see if my Chuquicamata visit might help solve the New Cornelia problem. While the difficulties were finally solved, at times they seemed almost hopeless. About all I could do to help was to make sure that the ore sent to the pilot plants represented the average ore that must be treated in the final 5000 tpd mill. Dr. Ricketts and John Greenway worked tirelessly with the best consulting advice they could obtain. Credit for the final success was due chiefly to their efforts. Since our old group had given up its "Merry Widow" home in Warren, a few of us got rooms in the company-built Cole Building over the Warren grocery store. This included Jim Lewis, Roy Mitchell, Steve Landon, Paul Stevens, and Hubert d'Autremont who came from Duluth to join our legal staff. Later we rented a small house two blocks from the Calumet and Arizona office. With the now flourishing country club only a 10-min walk away, and an electric car running to it every half hour or so, we were able to give parties in return for the hospitality of our friends. One of the most pleasant episodes came by luck a few days after I got back from Chile. Chester Congdon, a leading director in Calumet and Arizona, with his wife and their daughters, Elizabeth and Helen, spent a couple of days at the Greenway house before making an auto- mobile trip across the desert from Tucson to Ajo. At the same time I arranged to examine the small but rich Bush and Baxter copper mine a few miles from Tucson. At a party in Warren we found we would all be staying at the Santa Rita Hotel in Tucson, and I took my South

Jan 1, 1976

By Landy Stinnett

"When performing a valuation of a mineral property, a developing mine or perhaps an ongoing operation, the appraiser is typically provided with a range of information prepared by the property owner. This information can include ownership records, geological interpretation, assay data, an estimate of the reserves or resources believed to be on site (tons and grade), mine plans, production forecasts, capital and operating cost projections, and so forth.The appraiser familiarizes himself with the data, analyzes the various reports and then prepares the appraisal. There is usually a site visit, and there may be some effort at comparison of the particular mineral deposit with others in the region or with those of similar depositional characteristics, but for the most part, the appraiser is relying on the corporate documents, tempered by his/her experience in the field. Time is usually of the essence, the cost for the assignment has been trimmed, and therefore independent verification of the various components comprising the underlying data base (legal review, redrilling portions of the deposit, collection of new samples, re-assaying, etc.) is unlikely in most situations.In the case of high-value commodities — gold, silver, diamonds, perhaps the platinum-group elements — there have been numerous examples of the property owners attempting to increase the value of their holdings by nefarious methods. Most of these involve salting the deposit in some fashion; i.e., introducing small amounts of the commodity into samples being sent to a laboratory for analysis so that the resultant assay shows a higher grade (Donaldson, 2002; Greeley, 2001; Lechler et al., 2008 and Meech, 2001). Other schemes to enhance the apparent worth of a property include the use of nonstandard assay procedures, incorrect handling or withholding of the underlying information, and false reporting."

Sep 1, 2016

By D. M. Muir

Thiosulfate offers a non-toxic alternative to cyanide for processing gold ores. The mechanism of leaching gold using ammoniacal thiosulfate solution is driven by the Cu(II)-Cu(I) redox couple and is complicated by competing ligands such as NH3 and S2O32-. It is shown that an understanding of the copper speciation and sulfur speciation is required to optimise this system. This paper presents Eh-pH and speciation diagrams for varying concentrations of Cu(II), S2O32- and NH3 and discusses the conditions under which various copper and sulfur species are stable.

Jan 1, 2001

By Kyoosang Yoo

The report presents the results corresponding to the analysis of a lining system for tunnels in soil and soft rock in creep-active ground. The purpose of the analysis is to evaluate the performance of a lining at each construction stage. The steps include: 1. Accurate representation of the initial undisturbed state of stress 2. Excavation, 3. Lining installation 4. Injection of mortar and its curing, and 5. Short-, medium- and long-term creep behaviour in the surrounding soil/rock. The response of a prototype tunnel is simulated using the computational finite element framework MSC.marc2008.

Jan 1, 2010

By P. J. Bethell

Background Increasingly complex geological conditions, with the presence of high ash binders in the mining horizon were encountered at the A.C. I. Dugout Mine near Price, Utah. This led to the production of high ash coal from the Dugout Mine during 2003 and 2004. This material had poor marketability and posed operating issues for the utilities burning the coal. Ash levels increased from typical levels in the 9-12% range to between 15 and 25%. etween 15 and 25%. Reviews of the mine plan and expected geological conditions indicated that further periods of high ash production could be expected. Action Plan Detailed sampling of the mine high ash production was carried out. The majority of the coal from the Dugout Mine is trucked to the Savage Coal Terminal (SCT) at Wellington, Utah where it is stored in multiple piles by quality. Coal at the mine is segregated by a CoalScan 2600, on-line analyzer into high ash, low ash and rock chute (waste material). From these piles, the material is crushed prior to shipment to SCT. The samples obtained from the various high ash piles were subjected to detailed sizing and washability analysis. Once this information was obtained, alternative circuit configurations were evaluated to process this material into a salable product. Water supplies in the arid terrain where the plant is located are scarce. This factor played a part in the final circuit design.

Jan 1, 2008

By Don Phelps, Dean Brox, Peter Procter, Andy Saltis, Tom Morrison, Jeff Pringle

The Greater Vancouver Water District is currently constructing the Seymour-Capilano Water Filtration Project to enhance the quality of drinking water in the Vancouver metropolitan area. The Seymour-Capilano Water Filtration Project comprises the 1,800 million litres per day Seymour-Capilano Filtration Plant, the 1,080million litres per day Capilano Pumping Station, twin tunnels with associated shafts, and the Capilano Energy Recovery Facility. The twin tunnels will convey raw water under pressure from the Capilano Reservoir to the Seymour Filtration Plant and return treated (filtered) water for distribution. The Twin Tunnels component of the project comprises twin, 3.7 m diameter, 7.2 km TBM bored tunnels, the 180 m deep Seymour Shaft as the main launch shaft, and two 4 m diameter, 268 m deep raise bore exit shafts at Capilano. The Twin Tunnels have been planned as predominantly unlined tunnels sited at depth entirely within granitic bedrock and cross under two major buried glacial valleys of breadths in excess of 1500 metres that are filled with glacial sediments to depths up to 200 metres. The maximum overburden along the tunnel alignment is approximately 400 metres. Comprehensive site investigations and studies were completed during the detailed design stage of the project. The construction of the twin tunnels started in the fall of 2004 and is planned to be completed by mid-2008.

Jan 1, 2005

The title of “the world’s biggest volume-produced hydraulic breaker,” that was held for more than a decade by the Atlas HB 7,000, changed hands with the launch of Atlas Copco’s HB 10,000 at bauma 2007. A service weight of 10 t (11 st) and up to 50 percent higher productivity represent major steps toward a new market segment: the use of hydraulic breakers as cost-efficient production machines for primary breaking and as a true alternative to drilling and blasting. The HB 10,000 has all the technical features developed by Atlas Copco for its hydraulic breakers and includes: StartSelect — the breaker’s start-up and shut-down behavior can be adapted to the conditions. AutoControl that ensures an optimized balance of impact energy and impact frequency to maximize percussive performance. Auto-Control also reduces blank firing force and controls energy recovery. PowerAdapt — if oil pressure is too high, the breaker shuts down automatically. This prevents downtime and is particularly useful when breakers are used on different carriers. DustProtector II — a combination of multiple strippers prevents abrasive rock dust and foreign bodies from penetrating the lower breaker section. Conti- Lube II — the automatic lubrication unit guarantees optimal lubrication of the breaker at all times.

Jan 1, 2007

By Anna Sukhanova, Svetlana Babaeva, Sergey Andreev, Victor Beltenev

"The Zenith-Victoria /1/ and Jubileynoye /2/ hydrothermal fields have symmetrical structural position on the Mid Atlantic Ridge (Fig. 1). In order to compare the evolution of hydrothermal systems, we conducted mineralogical and geochemical studies of SMS from both sites.Radiochemical and geochemical investigations of massive sulfides of the Zenith-Victoria field distinguishes three major stages of evolution: initial, interim and final represented by Fe-S, Cu-Fe and Zn-Fe types of SMS respectively /3/. In this talk, we describe the results of geochemical analysis of massive sulfides from the Zenith-Victoria field. Geochemical varieties of SMS are considered to be indicators of the evolutionary stages of the hydrothermal system."

Sep 1, 2014

By Adam Shang Robert Fu

The Yung-Chung-Tunnel in Taiwan, constructed for the Taiwan-East Railway Bureau, collapsed during construction when a water bearing, fractured marble zone was intersected. The inflow was approximately 4,000 liters/second. In spite of 30 relief holes the total inflow into the tunnel remained constant. The pre-excavation grouting through the re-aligned tunnel had to be conducted under extreme flow-conditions. A hot bitumen grouting program was selected for technical and economical reasons out of 13 international proposals. The technical challenges were: grouting under severe flow conditions high formation water pressures to be injected with hot bitumen at high temperatures and pressures The hot bitumen grouting program resulted in a dramatic reduction in the hydraulic conductivity and stabilization of the formation and facilitated a problem-free excavation.

Jan 1, 2007

By D. Parks, A. Miller, M. McNinch, R. Jacksha

Each year, hundreds of mine workers are involved in machinery-related accidents. Many of these accidents involve inadequate or improper use of lockout/tagout (LOTO) procedures. To mitigate the occurrence of these accidents, new safety methods are needed to monitor access to hazardous areas around operating machinery, improve documentation/monitoring of maintenance that requires shutdown of the machinery, and prevent unexpected startup or movement during machine maintenance activities. The National Institute for Occupational Safety and Health (NIOSH) is currently researching the application of Internet of Things (IoT) technologies to provide intelligent machine monitoring as part of a comprehensive LOTO program. This paper introduces NIOSH’s two phase implementation of an IoT-based intelligent machine monitoring system. Phase one is the installation of a proof-of-concept system at a concrete batch plant, while phase two involves scaling up the system to include additional sensors, more detailed safety/performance metrics, proximity detection, and predictive failure analysis.

By Mohamed A. Younis, Paul J. Headland, Paul H. Madsen, Vojtech Gall

INTRODUCTION A 100 ft long, 20 ft high and 18 ft wide NATM tunnel was excavated through grouted clean sands beneath a busy city street, including a variety of existing utility lines. The new tunnel associated with a hospital expansion will serve as a pedestrian tunnel connecting a parking structure with a new hospital facility. Tunnel construction started on December 15, 2005 when drilling for the grouting program started and was completed on May 26, 2006 when the tunnel final lining was completed. The tunnel was constructed by Kiewit Construction Company as a tunnel subcontractor to The Christman Company who is constructing the hospital facility for Spectrum Health in Grand Rapids, Michigan. URS was the project designer. GallZeidler Consultants, LLC were the contractor’s NATM consultant. PROJECT DESCRIPTION The Michigan Street Pedestrian Tunnel is a component of the Michigan Street Development located along the north side of Michigan Street NE between Coit Avenue NE and North Division Avenue in the downtown area of the Grand Rapids, Michigan. The Michigan Street Development includes a parking deck and four new towers to be constructed over the proposed parking deck. The tower planned furthest east is being developed by Spectrum Health as the Lemmen-Holton Cancer Pavillion. The purpose of the pedestrian tunnel is to connect the proposed Lemmen-Holton Cancer Pavillion with the future Spectrum building to be located on the south side of Michigan Street NE. The southern end of the tunnel was constructed with a bulkhead until the future Spectrum building is constructed at which time interconnection will be required. The tunnel site plan and profile are shown in Figure 1, Site Plan, and Figure 2, Tunnel Profile. Several challenges were faced during the design and construction of the Michigan Street Pedestrian Tunnel. These challenges included compressed design and construction schedule, maintenance of traffic and protection of old underground utilities. The tunnel was being constructed as part of the Michigan Street Development and coordination with other concurrent construction activities was required. The tunnel was constructed within a specified window of time to allow other associated construction activities to take place without compromising the overall project schedule. The design started in June 2005 and construction was completed by June 2006.

Jan 1, 2007

By E. Jackson

This paper describes highlights of the Placer Dome MiniMole project - the development and testing of a robotic machine for mining narrow ore veins. A prototype hydraulically controlled robotic machine was built and tested. The machine provided a platform for testing numerous cutters in the field. Other cutters, e.g. undercutting devices, were tested in the lab. Extensive analyses were done on specific energies and cutter penetration. Three sets of quarry trials were done, then the machine was tested in an underground mine. Rock UCS values varied from 180 MPa to 230 MPa. The paper includes lessons learned and recommendations based on the project findings.

Jan 1, 2007

By Alfred Weiss

Selecting a minicomputer is not unlike selecting a costly piece of mining equipment such as a truck, shovel, crusher, or conveyor belt system. A marked difference might lie in the frequency at which such selection takes place; another difference might be mine management's familiarity with mining equipment vis a vis a minicomputer. These basic differences might prompt a mining company to seek the aid of a consultant when selecting a minicomputer system. Advantages and Disadvantages The fundamental advantage of employing an independent consultant is that it provides management with a source of knowledge and breadth of experience not readily available within the organization. If the consultant has a minerals background, such knowledge and experience are further enhanced by actual experience in exploration, mining, and mineral processing. If the consultant has worked within a mining company, such hands-on experience is supplemented with a meaningful understanding of the client's business; this facilitates communication between the consultant and members of the client organization. The consultant has been, so to speak, "in the client's shoes." There are several other advantages. Since computer systems cut across organizational boundaries, the independent consultant may be able to move within the organization more easily than an inside staff person to collect necessary information. Also, detachment from any manufacturer should provide the client with an objectivity and a set of recommendations as near optimal as feasible. The principal disadvantages lie in the area of continuity and accountability. Once the consultant's report has been submitted and his recommendations implemented, a discontinuity might occur. Also, if implementation does not provide the desired results, the consultant might not be available to correct the situation or account for actions taken. Proper selection of consultant services, relative to kind and duration, and the consultant's method of operation, will often prevent many of these aftereffects. Services Offered The professional consultant can help a client: •Define and summarize information systems technology* needs; • Evaluate alternatives such as in-house capability and capacity, time-sharing, or service bureaus; • Prepare a formal request for proposal (RFP) to be submitted to vendors; •Evaluate vendor proposals; •Evaluate the economics of lease vs. purchase; and •Assist in the conversion and installation. Thus, consulting services may range from evaluating an existing system and upgrading to a larger piece of equipment, to selecting a new first-for-the-organization computer. First, Define and Summarize Needs Regardless of circumstances, the most valuable document required before equipment selection is the information system plan (I/S plan). It helps insure that the company's information needs are met in a cost-effective manner. An I/S plan is usually a comporient of the mining company's overall business goals. Since an I/S plan is a formal vehicle for establishing and communicating the direction the organization intends to take to satisfy information requirements needed to achieve goals and objectives, most initial systems services are likely to center around creating such a document or updating an existing document. The trend toward company-wide I/S planning is increasing in the mining industry; however, smaller scale efforts focused at the information systems needs to support an individual

Jan 11, 1981

By Hyung Jeek Kim, Jongmin Joo, Jonguk Kim, Jai-Woon Moon, Kyeong-Yong Lee

"Co-rich ferromanganese crusts (Fe-Mn crusts) distributed on seamounts in the western Pacific are potential economic resources for cobalt, nickel, platinum, and other rare metals in the future. Evaluation and selection of a mining site can be established based on abundance and grade of Fe-Mn crusts in the site as well as topography that should be smooth enough for mining operations. Therefore, acquisition of shipboard echo-sounding and acoustic backscatter data are prerequisite to the selection of potential mine sites in addition to visual and sampling operations. Acoustic backscatter data can be used to locate crust-covered areas on a regional scale with the understanding of acoustic properties of crust through its correlation with visual and sampling data.During an expedition that took place from January to March 2014, KIOST collected geophysical and geologic data to assess the resource potential for Fe-Mn crusts on three seamounts (guyots) in the Western Pacific. In OSM11, one of the three surveyed seamounts, three camera tows were performed to observe the distribution of Fe-Mn crusts on the summit and slopes of the seamount. Although sediments of various thicknesses generally cover most of summit region of OSM11, several regions with high backscatter signals occur on the periphery of the summit. The occurrence of Fe-Mn crusts, observed during the camera tows, on those high backscattered regions suggests that the backscatter signals of shipboard multi-beam sonar can reflect changes in the geology of the seafloor from sediment layer to Fe-Mn crust deposits. The Fe-Mn crust deposited around the summit region is worthy of notice because of its topographic characteristics, including shallow depth, flat or gentle inclined surface, and smooth relief, which are more suitable for mining operation compared to the flanks of seamount."

Sep 1, 2014

By W. G. Brunner

The slurry wall technique has undergone an evolution from its invention to its today’s status. In the early stages slurry walls were built with cable grab, later on with much stronger hydraulic grab and last but not least with the use of the cutter technique. The cutter allows thick walls with high verticality to extreme depths through hard soil and rock formations. With the rising demand of the construction of watertight diaphragm walls different joint systems have been developed. In addition to the rapid development of excavation systems it was necessary to improve slurry treatment and desanding plants, especially in conjunction with high performance trench cutters. Deep mixing methods can be used economically for the construction of cut-off or excavation support walls where other systems such as traditional soldier beams and lagging walls would yield unsatisfactory performance, where the installation of vibrated or driven sheet piles could cause vibration induced settlements and where concrete diaphragm walls would be time consuming and expensive. The new CSM method can largely replace the more conventional single or multiple auger methods of soil mixing or jet grouting. The cutter tool is similar to a cutter used in diaphragm walls or cut-off walls and is operated with a Kelly mounted on a drilling rig or rope suspended on a crane jib or mast of a base carrier. With this system much deeper walls can be installed and even hard soil layers can be penetrated.

Jan 1, 2007

By J. M. Wempen

Booster fans, large underground fans, can increase the volumetric efficiency of ventilation systems by helping to balance the pressure and quantity distribution throughout a mine, reducing leakage and reducing the total power requirement. However, in ventilation systems that use booster fans there is a potential for system recirculation, the leakage of return air to intake air, and also for localized recirculation near the fan through the bulkhead and airlock doors. Air that is recirculated locally decreases the system efficiency because the quantity of air flow through the fan increases without increasing the airflow throughout the system. To understand the detailed flow characteristics of a ventilation system with a booster fan, two-dimensional computational fluid dynamics (CFD) models were developed using the software Ansys-FLUENT. Though two-dimensional models do not represent the full complexity of the flow dynamics, they do provide a good representation of the flow characteristics and they allow for a qualitative analysis of how the flow dynamics are affected by the system characteristics. The CFD models were used to evaluate how the number of booster fans, the booster fan placement, the location and geometry of the fan installation and the construction of the airlock system affect the flow characteristics and the localized efficiency of the ventilation system.

Feb 27, 2013