Search Documents

By Anthony D. Barley

Over 60,000 multiple anchors have been used internationally since their introduction in the early 1990s, including 1000 in the United States. The multiple anchor system comprises a "multiple" of "unit" anchors installed within a single borehole - each unit anchor being staggered within the borehole length to mobilize its own capacity independently of the other unit anchors. These systems offer higher capacity than conventional anchors with identical bond lengths due to superior load transfer efficiency. The use of higher capacity anchors may allow reduction in the number of anchors required on a project, which results in time and cost benefits to the anchor installer, contractor, and the owner. Fully removable temporary multiple anchors are available, and have been used with consistent success. Three case histories are discussed highlighting the use of these systems

Jan 1, 2002

By B C. Povey, K Lagutin, M Mryasov, V Noll

The current Stoilensky magnetite concentrator comprises a three-stage crushing circuit followed by three stages of ball milling, grinding and concentration to produce a magnetite concentrate with 66.5% iron (Fe). The plant is built in four lines, three lines having four mills and one line with five mills, to treat 32 Mt/y of ore and produce 13.9 Mt/y of concentrate.NLMK, the owner, is Russia’s third largest steel maker and while the ore from the Stoilensky Mining and Beneficiation Plant (SGOK) provides the bulk of their supply, they still must buy ore from external sources at world prices. A decision was taken to expand the SGOK operation to supply all the NLMK concentrate, including the production of pellets.To commence the expansion, high pressure grinding rolls (HPGRs) were introduced as a fourth stage of crushing ahead of the first ball mill. This was a relatively low capital cost expansion and increased production by 12 to 15%, the cost being much less than an additional grinding line. The importance of this development was that earlier introductions of HPGRs in Russia had presented several problems so there was some reluctance to the initial concept. The even greater significance was that nearly every magnetite plant in Russia had a three-stage crushing circuit so the successful introduction of HPGRs was of interest to many operators.The design was developed by a team, consisting of Worley Parson, Mineralconsult and PiterGORproject (PGP), for the first four units to fit inside existing building structures. The first two units were commissioned in March 2016 and the next two units in May 2016, and production improved by over 12%. The design of the installation of the final four units is in progress and the installation is expected in late 2017.CITATION:Povey, B C, Noll, V, Lagutin, K and Mryasov, M, 2017. Introducing HPGR quaternary crushers in a Russian magnetite operation – challenges and solutions, in Proceedings MetPlant 2017, pp 84–100 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By Louis P. Domingues

As part of a study on high-temperature ceramic materials, the ammonium sulfate, carbonate, nitrate, oxalate, and sulfate salts of yttrium, lanthanum, and cerium were analyzed thermogravimetrically. The temperature ranged from room temperature to 1,500° C. Each salt was decomposed by heating at a rate of 2.5° C. per minute, and some of the salts were subjected to additional rates of 5° C. per minute or 10° C. per minute. The decomposition sequences have been identified, and the temperatures of formation of intermediate compounds and of the oxides have been determined. The minimum oxide formation temperature of a given lanthanum salt exceeds that for the similar salt of yttrium, and both exceed that for the same salt of cerium except for one cerium carbonate. Variation of the heating rate indicates a thermal lag in the materials and produces the shift of formation temperatures to higher values and loss of resolution in the weight-loss distribution as the heating rate increases.

Jan 1, 1962

By J. D. Noll

Elemental carbon (EC) is used as a surrogate for regulating the exposure to diesel particulate matter (DPM) of underground metal/non-metal miners. EC was chosen as a surrogate because EC is selective to DPM and is a major component of DPM. Using EC as a surrogate also gives one the advantages of no sampling artifacts and being able to sample at all locations in the mine. Currently, EC represents DPM well in underground mines. Some control technologies have been shown to possibly alter the relationship between DPM and EC and characteristics of DPM. Therefore, future work will investigate the relationship between DPM and EC as new control technologies are implemented.

Jan 1, 2002

A variety of environmental financial assurance instruments are in use across the globe. This paper reviews some of the more common forms currently used in New Zealand, Canada, USA and Australia. In order to be effective, the form of assurance instrument selected needs to be aligned with a countryÆs specific environmental objectives, geography and political climates and also allow for a healthy investment climate. Industry and Government both have a strong interest in ensuring financial assurance criteria meet these objectives.   Recently Golder Associates have been involved in financial assurance assessments for various mining and quarrying companies across the South Island. Multiple stakeholders and regulatory agencies can make the setting of effective and fair financial assurance criteria a complex exercise for both regulatory agencies and industry.  The author relates experience gained in assessing financial assurance under current New Zealand legislation (RMA, 1991), effectively dealing with issues such as ôdouble bondingö and overviews potential approaches to dealing with transitional issues for historic and existing operating mine sites.

Jan 1, 2006

By James McNally, Adam Stremcha, John MacGregor

With 13.7km of TBM tunneling in Atlanta’s hard gneiss well under way, drill and shoot work continues on several sites throughout the city. In order for the City of Atlanta to meet the consent decree imposed by the federal government, an aggressive construction schedule was a necessity. Construction consists of two deep, large diameter tunnels, four construction shafts, a pumping station, one overflow shaft, three large intake structures, and two connecting tunnels. Due to the multitude of blasting insensitive urban environments, a high standard of seismic and air-overpressure criteria, coupled with time restrictions, was adopted for the project. At any given time, drill and blast operations were under way at four of the seven sites requiring a certain amount of coordination between the TBM excavation, surface work, and the forces of Mother Nature. This paper addresses the challenges faced and the techniques used to safely and successfully complete the rock excavation of the West Area CSO Tunnel and Pumping Station project.

Jan 1, 2007

By Derek J. Lennon

Ground conditions in central Glasgow generally comprise loose granular deposits overlying stiffer soils. CFA piling would normally be preferred for urban sites in these ground conditions, but flighting of the superficial deposits has on occasions resulted in building damage. Over the last five years rotary bored piling with vinyl polymer support fluid has proved to be an economic alternative to bentonite slurry. Two case histories in central Glasgow are described in this paper, one for piles founding in granular soils and one for piles founding into bedrock. A comparison is made between the methods required for disposal of the liquid waste from bentonite and vinyl polymer slurries.

Jan 1, 2006

By Christopher Jon Preston

This paper describes a type of ammonium nitrate (AN) produced in a patented experimental atomization/aerodynamic process. This AN exhibits outstanding properties for use as a main ingredient to a new family of AN-based commercial explosives. Micro-particle ammonium nitrate (MP-AN) is produced by atomizing either an 83% or 85% AN solution which has been doped with a two component surfactant NSol 1000 (NSol). NSol imparts some water-resistance as well as provides a means of increasing density and bulk strength. Increased detonation velocities, well in the range of emulsion explosives, can be achieved. The maximum manufacturing temperature is less than 100°C. The methodology has the potential of being environmentally friendly since any effluent can be recycled back into a make-up tank to be re-used by the closed loop method. The process has a small footprint.

Jan 1, 2015

By B. B. Broms

A method for calculating the bending moment induced in misaligned or bent piles is described, The maximum bending moment varies with the angular rotation between the pile segments, the coefficient of horizontal subgrade reaction of the soil and the flexural rigidity of the piles. A case history involving damages to misaligned 365 x 365 mm square precast concrete piles is described.

Jan 1, 2010

By K. Biswas, S. Iverson, S. J. Jung

Computer modeling of rock flow in ore passes is being investigated and compared using MSC Soft-ware’s Working Model 2D1 (WM2D) and Itasca Corp.’s Particle Flow Code in Two Dimensions (PFC2D). This work is being carried out by the Spokane Research Laboratory of the National Institute for Occupational Safety and Health to determine the usefulness of computer modeling to improve ore pass design. The types of tests included pendulum tests to validate WM2D simulations and simulated single-rock drop tests in both WM2D and PFC2D to understand their contact models. Simulated rock impacts at the ore pass chute and the use of inclined ore passes and doglegs were investigated in both programs. A PFC2D simulation showed that dynamic loads at the chute gate were reduced significantly when a dogleg transition was used, and simulations in which the ore pass was inclined showed significant reductions in chute impact loads compared to simulations of a vertical ore pass. A released hang-up was simulated using PFC2D.

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 Jan E. Nesset, Colin Hardie, Peter Radziszewski, Donald P. Leroux

"The successful introduction of new high intensity stirred milling technologies (e.g. IsaMill, SMDetritor) to the mining industry in recent years prompted Noranda-Falconbridge to initiate a study comparing these technologies to the conventional technologies of ball milling and existing vertical stirred mills (e.g. VertiMill). The study was unique in that it utilized the same material (Brunswick Mine zinc cleaner regrind mill feed), the same sizing instrument (a Malvern laser difractometer) and sampling protocol, and media size and type (for the high intensity stirred mills). The paper compares the net energy efficiency (kWh/t) of the various technologies, their power intensity (kW/m3) and product size distribution spread (P80/P20). A key finding is that media size is critical to achieving optimal performance. As part of the performance comparison, an analysis of the four methods of power measurement was made (Prony brake, shaft torque, grinding chamber reaction torque, “no-load” correction) and followed-up with an experimental test procedure using three of these methods. The findings include divergent results for power measurements and some explanations based on the observations are proposed. The direct shaft torque and Prony brake calibration methods are shown to be the methods most suitable for stirred mills.INTRODUCTIONThe motivation for the investigation reported here was the lack of a suitable comparison within the available literature of relative grinding efficiency for the emerging crop of new industrial fine grinding technologies. Such comparisons are potentially fraught with inconsistency, from ore samples and grinding media used, to testing methodology, to size measurement techniques, to the power measurements themselves. The collaboration of the industrial suppliers (at the time MIM Technologies and Svedala, now Xstrada Technologies and Metso Minerals) and McGill University (P. Radsiszewski) were sought in order to ensure as valid a comparison as possible. The work was performed between October 2000 and November 2002, led by the mineral processing group at the Noranda Technology Centre (NTC) in Pointe-Claire, Quebec. The paper is presented in two sections; Part A considers the different power measurement methods and a comparison of the results for the SMDetritor (SMD) technology, while Part B reviews the grinding performance of the 5 technologies investigated using the selected performance criteria."

Jan 1, 2006

By E. Sharifi

Advanced Process Control (APC) has been one of the most beneficial tools in the past decades available to minerals processing industry. Low capital cost together with significant improvements in process optimization have made APC an attractive investment option for nearly all mineral processing units. During economic downturns, importance of process optimization becomes even more relevant as metal producers tend to target de-bottlenecking and process efficiency improvements rather than large-scale capacity upgrades. APC project clearly has a lot of potential to improve process performance but there are also some pitfalls to be identified and avoided in order to achieve a desired outcome. Above all, APC project implementation is collaboration between the system vendor and user. Targets for the optimization must be agreed together with the customer and process performance must be defined before and after the optimization project. Most importantly, performance of the process must be monitored on a continuous basis during and after the project and potentially improved further. This paper discusses Outotec’s experiences from various concentrator optimization projects. Some examples are discussed in more details; however, the main target is to present general guidelines enabling a successful APC project implementation.

Jan 1, 2014

By Stephen C. Tadolini

The U.S. Bureau of Mines has developed ultrasonic measurement instrumentation capable of measuring strains and elongations on tensioned and untensioned mine roof bolting systems. This report evaluates the pulsed-phase-lock-loop and pulse-echo systems. The pulse-echo systems measure time of flight of a signal through the bolt. The ultrasonic instrument converts the measurement into elongations or stress. The most recent Bureau instrument development converts travel-time measurements directly into elongation, load, stress, and torque by simple data manipulation from the keyboard. Bolt preparation and instrument calibration are described in detail.

Jan 1, 1990

S. R. Carter (Mount Isa Mines Ltd., Mt. Isa): I found many ideas to interest me in Haddon King's paper "Notes on Ore Occurrences in Highly Metamorphosed Precambrian Rocks" (Stillwell Anniversary Volume).At Mount Isa I have not been happy about some of the longstanding appreciations of the geological evidence as fresh data accumulated, and as more and more knowledge has been building up outside Mount Isa in recent years of sedimentary deposition of sulphides.Accordingly, I organized a small section of the Geological Department at Mount Isa at the beginning of 1958 under Senior Geologist, W. J. Murray to reappraise our geological record and investigate old interpretations and new ones that arise. The work is expected to take several years to complete, but it is hoped that sufficient will be done before then to permit the most plausible story on the ore genesis to be chosen. In the meantime, W. J. Murray has proposed, in a Company Report, that the.epigenetic features of the silver,lead-zinc deposits, which are essentially conformable with the shales, could have resulted from remobilized syngenetic deposits.Haddon King, on p. 159; has listed six assumptions that are required by a magmatic-hydrothermal theory of, origin for conformable deposits. It is interesting to consider the Mount Isa silver-lead-zinc deposits in terms of these requirements.My comments are listed in the same order as Haddon King's assumptions:(a) "The source of the constituents is magmatic and they have become available in successive waves of zinc-rich, lead rich, manganese rich, silver rich, etc, instalments in accord...

Jan 1, 1959

By John G. Parker

The rare-earth elements, sometimes known as the lanthanides, comprise the series of 15 chemically similar elements with atomic numbers 57 through 71. Yttrium, with atomic number 39, is often included in the group, because its properties are similar and it more often than not occurs in association with the lanthanides. Thorium is included in this survey due to its close association with the lanthanides, particularly in the mineral monazite. The lanthanides were first recognized as elements around 1750 and were the subject of much study by chemists during the 19th century. The purely chemical methods then available failed to resolve the strange intimate relationships between these elements, and it was not until about 1920 that the full series was explained.

Jan 1, 1971

By A. Noble

The design of separation circuits can be a complex, labor-intensive and costly process. While the engineer?s experience along with extensive data sets and simulation are crucial tools for determining the final solution, a more fundamental approach is suitable to compare preliminary options and reduce the number of potential alternatives. In light of this need, the authors have developed the Circuit Analysis Reduction Tool (CART?). This software package relies on the fundamental principles of linear circuit analysis; however, the solution methodology has been streamlined to automatically incorporate stream splitting and unique separation performance for each unit. The resulting tool allows preliminary analysis of circuit designs without the need of detailed feed characterization. In addition to the basic analytical approach, this paper supports the veracity of the methodology with several simulated examples for various separation models.

Feb 27, 2013

By Circadian Technologies

Alertness levels naturally fluctuate during the day and night Basic functions ??digestion, body temperature ? follow predictable 24-hour patterns Adjustment to night work creates health challenges for shiftworkers Performance decreases during overnight and post-lunch dip hours Fatigue supercedes training & experience Fatigue is a major cause of human error

Jan 1, 2010

By H. Hearnden

Whereas in the past, ladles were simply a means of transferring molten products from furnace tapholes to points of discharge be they casting pans or waste dumps, the ladle is now becoming a more integral and versatile piece of equipment in the pyrometallurgical plant. The drive behind this development is the need for continuous improvement in performance where better, faster and cheaper means remaining competitive in the global market. This paper will explore the technologies available for the rendering of a costly and otherwise cumbersome piece of pyrometallurgical equipment more efficient and versatile in adding value to the final product. Essentially it all revolves around heat and more importantly the loss of it when tapping. The common practice is to move the molten product to its point of discharge quickly with the minimum of interruption to prevent skulling and hence the cost associated with clearing it. The advances in Oxy-fuel burners, AC or DC ladle furnaces, converters, gas purging and high velocity, bath injection systems has increased the versatility of processes and enhanced the potential for adding value to intermediate products through down stream practices such as granulation and atomisation.

Jan 1, 2004

By Frank J. Arland

Augered-Cast-in-Place piles have been used successfully for many deep foundation applications. The four case studies discussed herein describe ACIP pile projects where problems developed during ACIP pile installation requiring changes to the method or sequence of installation. The case studies illustrate the importance of understanding existing subsurface conditions and project constraints when considering the use of this pile type. Ground loosening and over-excavation of soil during the augering process, a significant concern for fine to medium sands and non-plastic silts below the water table, can significantly impact adjacent structures. This risk needs to be evaluated during the pile selection process and generally can be mitigated, but not eliminated, by requiring the use of piling equipment with high torque and slow auger rotation speed to advance the auger with minimum amount of rotation. In some applications where high lateral stresses in the soil are present such as at the base of retaining structures, the use of ACIP piles may not be appropriate if structure movement is unacceptable. On the other hand, ACIP piles have been successfully used to support deep foundations in preconsolidated varved deposits where the new structure was designed to accommodate recompression settlement.

Jan 1, 2004