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By Lance A. Roberts

Micropiles are commonly utilized for applications other than foundation retrofit. In bridges, for example, micropiles can serve as the permanent foundation elements or can be used in temporary support applications. In this paper, a case study on the use of micropiles for the 18th Street Expressway Bridge rehabilitation/repair project in Kansas City, Kansas is presented. In the project, micropiles were utilized for support of six temporary jacking structures, which allowed the bridge to be lifted while repairs were completed. A group of six micropiles was required to support each jacking structure. The required compressive service load per micropile was approximately 300 kips (1300 kN) and the settlement of the micropiles under the service load was to be limited to 0.5 in. (12.7 mm). Two field compression tests were conducted as part of the project. The field load test data was integrated within a soil-structure interaction capacity approach in order to analyze and permit the shortening of the design bond length for the production micropiles.

Jan 1, 2009

By M. Botz

Alacer Gold Corporation is constructing the Çöpler Gold Mine in eastern Turkey. Mining commenced in the fourth quarter of 2009 and gold production started in the fourth quarter of 2010. The mine is a 15,500 t/day oxide heap leach with three-stage crushing, agglomeration, carbon adsorption and electrowinning for final metal recovery. Leach solution copper levels are expected to be relatively low during the first two years of production, but will increase in later years due to higher copper content in the mined and processed ore. Over the mine life, approximately 40 Mt of ore will be placed on the leach pad, which will contain about 35,000 t of copper. Metallurgical testing indicates copper extraction will vary by ore type and, if controls are not implemented, may lead to copper levels exceeding 1,000 mg/L in pregnant solution. High copper levels in leach solution have the deleterious effect of increasing cyanide consumption and potentially overwhelming the ability of the carbon circuit to effectively adsorb the principal economic metals, which in this case are gold and silver. Using data obtained from laboratory leach column testwork, the heap leach facility was modeled using METSIM process simulation software to estimate the build-up of copper in leach solution over the life of the mine. Laboratory testwork was also performed to evaluate process conditions for treating a portion of pregnant leach solution via sulfide addition to precipitate saleable copper as copper sulfide (Cu2S).

Jan 1, 2011

By K Nilsson, D Connelly

Troy Resources acquired the Karouni Gold Project in Guyana, South America in 2014 and immediately proceeded to a Pre-Feasibility Study and project implementation. The study considered two open pit mines feeding a conventional carbon in leach (CIL) gold plant with a capacity of 1Mtpa. The study assumed a total of 2.61 million tonnes of ore with an average grade of 3.84 g/t gold with a recovered gold production of 303,526 ounces over a three year mine life.The project development involved drilling metallurgical test holes, securing second-hand major pieces of equipment where suitable, and arranging shipping to Guyana. The remote location meant logistical considerations were paramount. The plant consists of conventional two-stage crushing with single stage ball milling and a gravity circuit. The tailings circuit includes DETOX.The extremely high rainfall presented challenges with water management and the necessity to dispose of clean water to the environment. The DETOX was also mandatory due to the highly sensitive environment and past history in the area. The criticality of this meant that in the design, any cyanide in the tailings would precipitate in a plant shutdown.Lessons were learned and the project has been both profitable and successful for Troy Resources in a new operating location. In addition, the project has created jobs, delivered royalties and brought new skills into an area where previously there was little current mining activity.CITATION:Nilsson, K and Connelly, D, 2015. Karouni Gold Project from drill core to commissioning, in Proceedings MetPlant 2015, pp 197–206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By Les Johnston

_ BACKGROUND - About EPCOR - Genesee Generating Station - Phase 3 Expansion _ TECHNOLOGY SELECTION - Selection Criteria - Combustion Options - Flue Gas Emission Control Options _ STAKEHOLDER VIEWS _ PROJECT STATUS _ EPCOR is an integrated utility company for water, gas, electricity and technology services. _ EPCOR has about 1.6 million customers in Alberta, Ontario, Manitoba, BC, and the U.S. Pacific Northwest. _ EPCOR Generation Inc. operates three power stations in Alberta which were in operation before deregulation, including the coal-fired Genesee Generating Station. _ EPCOR Power Development Corporation owns generating stations in Alberta, BC and Washington State and will be building the Genesee Phase 3 expansion.

May 1, 2002

By Segnit E. R

Results are reported of a study of the reactions occurringin the combustion of chaIcopyrite particles underconditions simulating those in the shaft of a flashsmelter.The reactions were studied using kinetic and mineralogicaltechniques. Reactions. rates above 500°C wererapid, most of the reaction taking place in less than 50ms. Final products were copper-iron ferrites with spineltype structures. Probable reaction mechanisms are discussed.

Jan 1, 1977

By F. E. Chase

Mobile roof supports are shield-type support units mounted on crawler tracks. Mobile roof support (MRS) units are used during retreat mining, and they eliminate the setting of roadway, turn, and crosscut breaker posts which are required during pillar recovery operations. Mobiles are a more effective ground support than timbers, and their usage enhance the safety of section personnel and reduces material handling injuries. MRS usage is rapidly increasing, and approximately 40 U.S. coal mines have successfully employed this relatively new technology. This paper is in response to increasing requests from operators, State and Federal Regulatory Agencies, and others on the practical aspects of MRS usage in underground coal mines. During this investigation, nearly half of the U.S. mines which have utilized mobiles were visited. This report depicts the more common pillar extraction methods which operators have found successful. The Christmas tree and outside lift methods are illustrated and discussed. Roof control plans that do not require breaker posts or allow pillar extraction with fewer than four mobiles are also examined. In addition, operators' experiences with setting pressures, loads, and rates of loading during pillar extraction are addressed. Mining and support strategies to more effectively control hillseams, weak roof, and gob overrides which have entrapped equipment are also discussed.

Jan 1, 1996

Jan 1, 1967

By P. P. Andrieux

The recovery of the Zone G crown pillar, located between the bottom of the open pit and the top of the underground workings at the Raglan Katinniq Mine in Nunavik, started in the summer of 2008 and should be completed by the end of 2009. This article describes the rock mechanics-based approach implemented to design the recovery of this valuable block of ore. The stereophotography-based ShapeMetriX3D technique was first used to provide a comprehensive assessment of the various joint sets that comprised the pillar. Then, the statistical distributions obtained for the dip, dip direction, spacing and persistence of these sets were used in conjunction with the geometry of the large-scale faults present in the area to build and run a series of explicit rigid numerical models. Each of these models had a slightly different jointing geometry, randomly constructed from these statistical distributions. Incorporating in a properly formulated numerical model the variability of some of the input parameters has allowed the engineering team to assess in a rational and reliable manner the likelihood of success of the proposed mining method and sequence.

May 1, 2009

By M. Vanpée, H. G. Wolfhard

Jets of hot gases issuing into explosive gaseous mixtures are efficient agents of ignition . The ignition temperature is defined as the temperature of the jet as it enters the cold explosive mixture which is just high enough to produce ignition . Such data have been published recently.5/ The investigators note especially that no correlation seems to exist between hot - gas ignition temperatures and spontaneous ignition temperatures , although there is a rather loose relation with limit flame temperatures . Before a more quantitative theory of the hot - gas ignition process can be attempted effectively , several questions must be answered : ( 1 ) Can the reactions leading to ignition be described by an Arrhenius type activation energy? ( 2 ) Is ignition preceded by an induction period ? ( 3 ) What is the rate - determining process of the ignition ? (4) And how does turbulence affect this type of ignition ?

Jul 1, 1960

By Stephen C. Tadolini, Thomas E. Marshall, Cecil Banta, L. J. Prosser, Anthony T. Iannacchione

The Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) endeavors to provide national and world leadership in the prevention of work-related illness, injury, and death. This is accomplished by using a scientific approach to gather information, assemble and create knowledge, then translate the knowledge and results into products and services. These products and services are then delivered to all personnel who can effect prevention. Obviously, the development and use of instruments to monitor mine roof conditions provides an opportunity to execute that mission. In the late 1990’s, based on observations at a number of underground limestone mines, only a few used roof monitors. Subsequently, NIOSH introduced the Roof Monitoring Safety System (RMSS) as an aid to roof inspection beyond traditional visual and sounding techniques. Initial expectations were that by gaining roof movement information, ultimately roof sag rates could provide indications of eventual failure. During this investigation, RMSSs were installed in 13 underground limestone mines in six states and this paper analyzes the data obtained at three of these mines. This paper also provides an overview of the system, data, analysis, and applications relevant to the RMSS.

By D. Pappas

Over the past decade the number of contractors working in underground coal mines has nearly doubled; however, the effect this has had on the industry?s injury rates has been the subject of much speculation. The confusion exists because the U.S. Mine Safety and Health Administration (MSHA) database does not assign contractor hours to the individual mining operations where they worked. To better understand the safety record of the contractor segment of the industry, the National Institute for Occupational Safety and Health (NIOSH) undertook a comprehensive analysis of the data contained in the MSHA database. The first part of the study compared overall contractor and operator trends from 1983 to 2009 related to employment, hours worked, injury rate, and days lost. One unexpected finding was that the larger contractors tended to have higher injury rates than the smaller ones. The second part of the study directly addressed the role of contractors on the safety record of 10 large underground coal mines. A detailed analysis provided both injuries and estimated contractor hours worked at these mines for the period 1992?2007. Comparison between the estimated contractor injury rates and the reported operator injury rates at these mines indicated that the contractor injury rates were significantly higher at most of the operations studied. However, the industry-wide data indicates that contractor and operator injury rates have converged since 2005 and are now equivalent.

Jan 1, 2011

By C Li, D O’Dea, R Moreno-Atanasio, T Honeyands

The behaviour of iron ore granules in the feeding process of sintering is significantly influenced by the material properties of the granulated mix. Therefore, the measurement of key material properties of the iron ore granulated mix is indispensable prior to the simulation of the sintering process based on the discrete element method (DEM). In this paper, three key property parameters of the iron ore granulated mix, apparent density, elastic modulus and rolling friction coefficient, were measured in laboratory-scale experiments. For different sintering processes, the moisture content of the granulated mix normally varies according to the specific requirements for granule size distribution and operating conditions. Therefore, understanding the effect of moisture content on the property parameters of iron ore granules is very helpful in accurately determining the property parameters for DEM simulation work. In this paper, six groups of iron ore granule samples with six levels of moisture contents were prepared through granulation and the trends in apparent density, elastic modulus and rolling friction coefficient with the increase of moisture content were plotted and analysed based on the measurement results. The results show that as moisture increases from 6.9 per cent to 9.1 per cent, the apparent density decreases from about 3000 to 2800 kg/m3. With moisture increasing within the same range, the elastic modulus first decreases from over 200 MPa to below 100 MPa and then reaches a relative constant value of about 40 MPa at higher moisture contents. Rolling friction coefficients are measured using two methods with both indicating a similar trend, with the rolling friction coefficient first decreasing and then rising as moisture increases from 6.9 per cent to 9.1 per cent. The relationship between µr and µ’r is assumed to be similar to that between static and dynamic friction coefficients.CITATION:Li, C, Moreno-Atanasio, R, O’Dea, D and Honeyands, T, 2017. Variation in property parameters of iron ore granulated mix with moisture content, in Proceedings Iron Ore 2017, pp 79–84 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By G. S. Hansford, C. J. N. Dempers, G. E. Searby, A. W. Breed, M. A. Jaffer

The bioleaching of sulfide minerals involves a ferric attack of the mineral with the role of the micro-organisms being the oxidation of the ferrous-iron back to the ferric form, and the oxidation of sulfur, either via thiosulfate or polysulfides, to sulfate. The kinetics of bacterial ferrous-iron oxidation and the chemical ferric leach kinetics of sulfide minerals can both be described as functions of the ferric/ferrous-iron ratio. The independently determined bacterial ferrous-iron oxidation and chemical ferric-iron leaching kinetics have been successfully used to predict continuous bioleaching operations.

Jan 1, 2000

Cyclone Process for Heavy Metals Decontamination of Sediments

Sep 13, 2010

By Masaki Kitazume

"Abstract The wet type and dry type of deep mixing methods have been developed and widely applied for on-land and marine constructions in Japan. The quality assurance (QA) of the methods has been usually carried out by unconfined compression test on field stabilized soil sampled by core boring in Japan. In some other countries, stabilized soil excavated by the wet grab sampling instead of core sampling is often subjected to unconfined compression test for quality assurance. There are several merits and demerits in each method, but few studies have been carried out to compare the stabilized soil strength of these two types of specimens to discuss their applicability to practical construction. The author has conducted a series of field and laboratory tests to compare the stabilized soil strength and discuss the applicability of wet grab sampling to QA for wet and dry types of deep mixing method.In this study, the wet grab sampling was carried out at two road embankment construction sites where the wet type and dry type of deep mixing were applied. The cement stabilized soil was excavated at the three depths by a wet grab sampler soon after the DM column construction. The test result is compared with the other test data in the previous study to discuss the applicability of the web grab sampling method for QA of cement stabilized soil.IntroductionThe Deep Mixing Method (DMM), an in-situ soil stabilization technique using cement and/or lime as a binder, is often employed to improve soft soils (Kitazume and Terashi, 2013). A variety of factors and their interactions affect the eventual strength of a deep-mixed column, while some of which are controllable (e.g. binder type and dose) by engineers while the others are not (e.g. soil types, ground temperature, etc.; Babasaki et al., 1997). In addition to laboratory mix tests, which in essence are a parametric study to estimate the influence of these factors on a particular soil’s strength, the quality assurance (QA) practice in Japan usually involves unconfined compression test on sampling cores from the stabilized columns after a given curing period. It has been recognized, however, that the ‘field strength’, or the strength of the retrieved core, quf is on average lower than the ‘laboratory strength’, qul, evaluated by laboratory mix test. Also allowing for the inevitable variability, existing guidelines (for example, PWRC, 2004 and CDIT, 2008) recommend the design quf /qul values of, for example, 0.5-1.0 for the CDM (Cement Deep Mixing; a wet-type technique, in which binder is added as slurry) and 0.2-0.33 for the DJM (Dry Jet Mixing; a dry-type technique, in which binder is added as powder)."

Jan 1, 2014

By Cary Hirner, David Stacey, William A. Rochford

Design considerations and construction techniques were implemented to address groundwater infiltration from a confined aquifer during the excavation and lining of the Cady Marsh Flood Relief Tunnel. This 3-m finished diameter, 2-km long tunnel was successfully completed cost-effectively in an urban setting near East Chicago, Indiana. The soft ground was mined using a conventional tunnel boring machine with hydraulically actuated flood doors and supported with steel ribs and timber lagging. The tunnel was lined with cast-in-place concrete. Dewatering was implemented in settlement prone, boulder-laden ground in residential neighborhoods during construction to depressurize and partially dewater the aquifer at the tunnel horizon. This paper describes the design decisions and construction methods utilized to mitigate and limit infiltration into the tunnel during construction and operation, as well as manage ground settlement.

Jan 1, 2007

By Gerald L. Stolarczyk

Safe and efficient coal extraction requires advanced radar subsystems that can be mounted on cutting drums of coal cutting machines. A look-ahead radar (LAR) must solve the radio geophysics problem of transmitting an electromagnetic (EM) wave through at least 20 feet (6.1 meters) of coal to an air- or water-filled void. The reflected EM wave must be processed in the radar electronics to determine the physical distance to the void. Horizon sensing enables selective cutting near the undulating sedimentary rock boundaries of the coal bed to address coal quality and ground control issues. Both sensors require subsystems for dynamic electric power generation, real-time measurement of drum rotation angle, detection of reflected EM waves, and processing to determine distance through coal and RF modem transmission of measured data to the mining machine. This paper describes the development of the subsystems and field test results.

Jan 1, 2006

Tunnelling under squeezing ground conditions poses significant challenges. There are fundamental differences in the choice of support for mining as opposed to civil engineering. This paper reviews ground support strategies that have been used to control large deformations in mining excavations based on field data from five different mines in Australia and Canada. Recommendations are made for improved ground control strategies in squeezing rock conditions.

Jan 1, 2008

By K. Parameswaran, A. Veek, A. Fernandez, P. Safe

ASARCO LLC (Asarco) Hayden Copper smelter, in Hayden, Arizona, has operated continuously (except for minor labor and economic curtailments) since 1912. The current plant configuration comprises INCO flash smelting, Peirce Smith (P-S) converting and fire refining/anode casting. In order to comply with the U.S. Environmental Protection Agency (EPA) 1-hour National Ambient Air Quality Standards (NAAQS) for sulfur dioxide promulgated in June 2010, the Hayden smelter had to increase overall sulfur fixation from approximately 95 % to 99+ %, requiring a retrofit of the existing converter department and upgrade of associated emissions controls systems. The Converter Retrofit Project (CRP) involved replacing the five existing 13’ diameter Peirce-Smith converters (2 blowing, 2 hot standby) with three new 15’ diameter Peirce- Smith converters (1 blowing, 1 hot standby) to allow for more effective process gas capture using the existing acid plant contact section. Significant upgrades were made to the acid plant wet gas cleaning section and converter primary gas handling system to improve capture performance, reliability, and sludge handling. In addition, a new tertiary gas capture system was installed to further minimize fugitive emissions from the converter aisle. The existing furnace tapping ventilation ESP was replaced with a new baghouse to enable at least 50% SO2 removal using high-surface-area dry lime injection, which was also implemented on the existing converter secondary gas baghouse system. The first two converters and all gas handling system improvements were started up in April 2018, and the third converter was brought online in November 2018. This paper presents the regulatory context; genesis and rationale for CRP; detailed description of the project; challenges during commissioning; system improvements implemented, and design considerations made, and systems performance and process optimization achieved since startup.

Jan 1, 2019

By I. W. van der Merwe

Recently, a new kind of filtration has emerged, namely nano-filtration (NF). It is a membrane-based process which exhibits totally unique separation characteristics for dissolved salts as well as for many non-charged species. By exploiting the particular separation characteristics of this new membrane type, many unique and novel separations have been made possible. The basis for separation by nanofiltration is the negative surface charge of the membrane. This results in rejection of multivalent anions, whilst associated cations are also rejected to maintain electro-neutrality. This peculiar property enables separation of dissolved ions such as sulphate and copper from acid, whilst the acid may be purified for reuse. This paper aims at providing an overview of the principles of nanofiltration, illustrated by particular examples.

Jan 1, 1998