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By Yuemin Zhao, Wenxuan Liu, Maoming Fan, Zhanyuan Long

"Coal is mainly composed of energy-producing elements carbon and hydrogen. In addition to these elements, coal usually contains many other valuable elements, including iron, aluminum, silicon, rare earth elements, lithium, gallium, germanium, vanadium, uranium, titanium, scandium and phosphorus. These coalassociated elements are significantly enriched in coal combustion byproduct fly ash because the majority of the main components, carbon and hydrogen elements, being removed. Table 1 provides the chemical composition range of the main element oxides in 12 Chinese fly ash samples collected from coal power plants located in Northeast China, Northwest China, Southwest China and Southeast China. It can be seen from Table 1 that the major mineral components of different ashes are similar, but the bulk chemistry of different fly ashes may vary due to the changes of ratios of the mineral components in different coals. The major mineral components in various Chinese coal combustion fly ash are silicates, iron oxides and unburned carbon.Chinese coal fly ash usually contains about 5 to 15 percent of unburned carbon, which are generally chars with irregular shapes and wide particle size distribution. In addition to unburned carbon, XRD analysis of four Chinese fly ash samples from Liaoning, Shanxi, Guizhou and Shandong provinces indicates that the fly ash samples are composed of minerals such as quartz (SiO2), mullite (3Al2O3.2SiO2 or 2Al2O3.SiO2), hematite (Fe2O3), maghemite (gamma form of hematite, ?-Fe2O3) and magnetite (Fe3O4). The mullite and quartz particles are usually present as spherical particles because they are formed by melting clays, feldspars, quartz, calcite and other common minerals in coal during coal combustion. The silicate particles have usually entrapped gas to yield hollow spherical particles because their lower melting point facilitates gas entrapment.The iron oxides are usually spherical also. The magnetite (Fe3O4) is derived from pyrite (FeS2), hematite (Fe2O3), siderite (FeCO3) and limonite (2Fe2O3.3H2O) in the coal. Maghemite (?-Fe2O3) is formed by dehydration of the mineral hydrohematite (?-FeO(OH)) and/or oxidation of magnetite (Fe3O4) during coal combustion. Maghemite (?-Fe2O3) and magnetite (Fe3O4) are strongly magnetic, so they are recovered from Chinese coal fly ash and widely used for coal processing in China (Fan et al., 2005, 2000)."

Jan 3, 2018

By H. Mischo, F. Daniela, L. Schaarschmidt, I. Paschke

In order to safely store radioactive waste long-term, HAW repositories in saliferous formations have to be backfilled. The main purpose of those backfill operations is the restoration of the geological barrier function of the containment area. For best possible results the used material should be of a comparable composition or characteristic for the host rock formation. Additionally, the material should show a high density after completion of the backfilling process as well as a low permeability. A major aspect to consider in these processes is the minimization of the gap of the backfill body to the roof of the drift. To fulfil those requirements, a micro-structure stabilized crushed salt backfill material has been developed as part of the GESAV-I-project. Due to the material composition of this so-called GESAV-material, salt mineralcrystallization processes start after emplacing it, a process that leads to the polyhalite formation. With the crystallization of polyhalit, the halite grains are bridged, which in return stabilizes the matrix of the backfill. The GESAV-II-project continued successfully what GESAV-I started and determined an ideal backfill method in order to build the backfill bodies composed of GESAV-material. Due to the compaction of the material during emplacement by vibration, high in-situ densities, low permeabilities and a backfill factor close to 1 was able to be reached. In the following SAVER project this journey of practical test underground will be continued.

Mar 2, 2022

One of the critical challenges facing the mining industry ? and not just in the United States ? is the looming labor shortage. A significant percentage of the industry?s professional workforce is, well, getting old, and many will be retiring in the next 10 years or so. This is not a new issue to the industry. It has been discussed at various industry meetings and conferences for many years. How does mining, with its largely negative public image, attract young people to mining schools? And, equally important, who is going to teach them? Mining schools, what?s left of them in the United States, are beginning to lose qualified faculty to retirements, and no one is available to replace them. SME addressed this issue during the keynote session at its annual meeting in February in Denver, CO. This year?s theme was ?Mining: It?s About the People.? Despite a blizzard that blanketed the city on the day most attendees were to have arrived, the meeting still attracted a record 7,202 people. And the accompanying exhibit sold 822 booths, also a record. The U.S. Department of Energy?s National Energy Technology Laboratory contracted with the National Academies? National Research Council to complete a study concerning the availability of skilled workers to meet the energy and mineral security requirements for the United States. The National Research Council, in turn, asked SME to collect and analyze workforce trends in these industries. The result of SME?s analysis is the report ?Emerging Workforce Trends in the U.S. Energy and Minerals Industries.? It is available on the SME website, www.smenet.org. Click on Government Affairs. While the report did not paint a completely dismal picture, there were some disturbing results. It concluded that within 20 years there will not be a sufficient number of skilled professionals to satisfy the labor demand. That said, the report said that most of those positions would likely be filled. However, the U.S. mining will go through a period of time when the workforce will be made up of very young and senior workers.

Jun 1, 2013

By R. Rumpold, J. Antrekowitsch

"The continued increase of the automobile production leads to a higher platinum, palladium and rhodium (PGM) demand. Due to the high value of the PGMs the recycle of these metals from automotive catalysts is of special interest. Pyrometallurgical processes, which are only focused on the PGMs, represent the state of the art of automotive catalysts recovery. However, hydrometallurgical recycling processes offer additional recovery of other valuable metals and compounds. The method presented in this paper is based on a combination of hydrochloric acid and hydrogen peroxide to dissolve the valuable metal fraction which can be precipitated afterwards.INTRODUCTIONPlatinum and the corresponding metals from the PGM group, especially palladium and rhodium are well known as catalytic active materials. They support chemical reactions which are inhibited. This effect is used to decrease the amount of harmful compounds like hydrocarbons, carbon monoxide or nitrogen oxides in automotive exhaust gases. The generation of these toxic substances is based on incomplete combustion, which in turn is caused by non-ideal conditions in the combustion chamber. Catalytic converters minimize the harmful compounds by supporting the following Reactions 1 – 3 (Votsmeier et al., 2009).CO + ½ O2 ? CO2 (1)CnHm + (n + ¼ m) O2 ? n CO2 + ½ m H2O (2)2 NO + 2 CO ? N2 + 2 CO2 (3)Platinum and palladium are very effective for the oxidation (Reactions 1 and 2), while rhodium supports the decomposition of nitrogen oxides by carbon monoxide (Votsmeier et al., 2009). The classical three way catalyst was a platinum – rhodium combination with a Pt:Rh ratio of 5:1 (Hagelüken et al., 2005). Today the platinum, palladium and rhodium ratio is highly variable and strongly depends on the engine type as well as on the car producer. Diesel engines are operated with a super stoichiometric air addition in comparison to spark ignition systems. Therefore the exhaust gas composition and off gas temperature is different. Based on the high oxygen amount, diesel engines produce less carbon monoxide and hydrocarbons but more nitrogen oxide in contrast to gasoline engines. This leads to various requirements for the catalytic converters."

Jan 1, 2012

By W. L. Crentz

The Black Mesa coal field is part of the Hopi and Navajo Indian Reservation in Apache, Navajo, and Coconino Counties, Ariz. The field is in an isolated area with the nearest railroad 70 to 90 miles to the south. Travel is restricted by roads that become impassable during inclement weather. The area is a mesa and rises from 500 to 2,000 feet above the surrounding territory. Water is very scarce, and the nearest stream of any consequence is the Colorado River about 90 miles northwest from the center of the field. Coal beds are found in the Mesaverde formation of the Cretaceous age, but they are uncorrelated and range from subbituminous to bituminous in rank. Huddle2/ estimates the reserves of subbituminous coal in Arizona at about 15 billion tons, most of which is in the Black Mesa field. The geology of the field has been reported by Campbell and Gregory.3/ Coal production is small, and the output is used almost exclusively for domestic fuel in the Indian schools, missions, and trading posts.

Jan 1, 1955

By Yosry A. Attia

One of the most significant advances in Mineral Processing in recent years, is the development of the selective flocculation technology. The technology is primarily aimed at recovering the mineral values from ultrafine ore suspensions. This is achieved by selectively aggregating the mineral particles in question to such size as to enable their effective separation from the suspension. Selective flocculation utilizes the differences in the physical-chemical properties of the various mineral components in the mixed suspension. It is based on the preferential ad- sorption of an organic flocculant on the particular solids to be flocculated, leaving the remainder of the particles in suspension. In order to understand the mechanics of this process, selective flocculation may be divided into four major sub processes; these being: ore slurry dispersion, in which all the particles are stably and uniformly distributed in the suspension with the individual particles being essentially separate; flocculant selective adsorption and floc formation; floc conditioning, which aims at obtaining flocs with desire properties for their subsequent separation and with minimum entrapment of dispersed particles; and floc separation from the suspension. These sub processes will be reviewed later in this article.

Jan 1, 1982

By Larry L. Anderson

Enormous quantities of organic wastes are produced each year in the United States. The total amount is in excess of 2 billion tons and at least 880 million tons of this is moisture- and ash-free organic material (dry organic solids), representing a potential energy source of significant magnitude that is not being utilized. Bureau of Mines scientists have developed methods for converting these wastes to convenient energy forms. This report itemizes and evaluates for the first time in detail the quantities and sources of moisture- and ash-free organic material contained in manure, urban refuse, industrial wastes, sewage solids, and agricultural wastes in the United States. Furthermore, estimates are presented for amounts of organic wastes collected or concentrated. The potential for fuel, either oil or gas, from both the total organic wastes generated and those collected or concentrated is also estimated.

Jan 1, 1972

Real gross national product increased at a larger-than- expected annual rate of 8.3 percent in the first quarter of 1984, with both consumption and investment spending increasing significantly in real terms (table 1). Residential and nonresidential fixed investment increased at annual rates of 25.7 and 14.6 percent during the first quarter of 1984, and investment in nonresidential structures, which declined in 1983, also increased during the first quarter of 1984, nearly attaining its 1982 level. The annual level of personal savings increased $27.7 billion, while the personal savings rate (the ratio of personal savings to disposable income) increased to 5.8 percent during the first quarter. The increase in the personal savings rate comes as welcome news to analysts concerned over the flow of loanable funds to the private sector and the impact on interest rates in 1984 of increased private and Government demands. U.S. Minerals Industry Performance A major upswing in the performance of the metal mining sector occurred during the first quarter of 1984, with production increasing almost 11.2 percent from January to March, The recovery of the metal sector is also reflected in the performance of primary metal industry profits, which were positive during fourth quarter 1983 following seven consecutive quarterly losses (table 1). Two thousand nine hundred more metal mining production workers were employed in February 1984 than in February 1983.

Jan 1, 1984

By Corby G. Anderson

Hydrometallurgical technology for the pretreatment of refractory gold concentrates has been developed at Sunshine Mining and Refining Company. It employs a patented nitrous-sulfuric acid pressure leaching process which' was proven industrially at the Sunshine refinery. Additionally, pretreatment for removal of antimony and some other impurities is done with alkaline sulfide leaching. This paper will discuss the successful application of these two technologies for pretreatment of a refractory gold concentrate prior to CIL gold recovery. A complex gold concentrate composed of pyrite, arsenopyrite and stibnite was tested. Results of antimony leaching in alkaline sulfide media will be discussed including some details of a novel and selective recovery method for gold leached by polysulfide or thiosulfate" Also, the factors important in and the results of the application of nitrogen species catalyzed pressure leaching to refractory gold concentrates will be detailed.

Jan 1, 1996

By G Harbort, K Quan

Traditional engineering practice for concentrator design uses a mixture of risk minimisation options and capital minimisation approaches. Often this is based on the preferences and experiences of the engineers involved.A geometallurgical approach involves identifying primary lithology, alteration, and mineral dispersion patterns within a deposit to allow representative samples for test programs. This provides a method to infer from laboratory test results meaningful production data for larger amounts of the ore body. Geometallurgical models can be integrated into the resource block model and subsequent mine plan and can assist in predicting when difficulties in the processing route might be expected, allow adjustment of the design to compensate for these or provide an early warning system so that production forecasts can be more adequately developed. Simulation modelling is the process of creating a computer model of a real system based on mathematical logic. In simulated time, the model explores the randomness and chronological sequencing of events observed on real systems. The objective is to mimic the real system with sufficient accuracy to make predictions of real behaviour under experimental conditions. Amec Foster Wheeler often use the ‘discrete-event’ simulation modelling technique. This method is well suited for inclusion of the statistical variation of effects in unit operation, mechanical availability, throughput and operating strategy (based on historical operating data for equipment downtime), operating schedules and equipment capacity. The net result of the simulation model is an analysis that can quantify risks in terms of system performance and capital and operating costs.CITATION:Harbort, G and Quan, K, 2017. Concentrator design – standard engineering practice versus geometallurgy and simulation, in Proceedings MetPlant 2017, pp 195–206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By G Barla

In Europe, a major interest in the infrastructure and tunnelling fields is in the new crossings of Alps in the form of base tunnels, which are important components of the high-speed (for passengers)/high-capacity (for freight) Trans European railway corridors. These tunnels cross the mountain belt at the elevation of the main cities and basins located all around the Alps and are longer (up to 57 km) and deeper (up to 2500 m) than all tunnels constructed in the centuries before. The excavation of the first Alpine railway and road traffi c tunnels could in general be carried out successfully by conventional excavation methods. With the great lengths of the new base tunnels, mechanised excavation by using tunnel boring machines (TBMs) is imperative as it contributes significantly to savings in construction time and costs. Questions are however posed on the adoption of such a systematic tunnel construction method given the severe ground conditions which are some time anticipated along the tunnel alignment, with possible major geological hazards such as water inflow in heterogeneous fractured or karstifi ed rock masses, stress-induced tensile failure of hard rocks, and plastic shear failure and squeezing of weak rocks, etc. This lecture is to briefly review the current state-of-the-art in the understanding and modelling of two such critical hazards as spalling/bursting and squeezing ground behaviour. With the present interest in the design of mechanised tunnelling with TBMs in such conditions, the complex interaction between the rock mass, the tunnel machine and its system components, and the tunnel support is studied in detail by numerical modelling. The research and development efforts presently underway with the intention to provide the designer with a novel three-dimensional (3D) simulator of mechanised tunnel excavation are presented. Case examples are discussed with reference to the Lyon-Turin Base Tunnel design.

Mar 8, 2011

By D. Want

In titanium-lined autoclave design the most critical point of its mechanical reliability is its titanium batten strips present at the circumferential and longitudinal barrel-weld seams. Recently an Australian Company, W.E. Smith Hudson (WESH) P/L, has developed a fully flush batten strip and is building autoclaves with this design. Significant research and development has been performed in the process. In this presentation, design aspects of these batten strips are presented that cover topics such as residual-stress magnitudes during fabrication, affect of preheat during batten-strip welding and residual stress in respect to fatigue life. There has been little research done regarding the affects of residual batten stress in relation to fatigue life. Considerations of this 'grey' area of design will be discussed based on the author's research data and finite element analysis.

Jan 1, 2005

By Pedro Cunha Alves, Wagner Viana Bielefeldt, Vinicius Cardoso da Rocha, Julio Aníbal Morales Pereira, Antônio Cezar Faria Vilela

A limpeza e a reoxidação de um aço SAE 1055 modificado foram avaliadas durante a sua produção em uma aciaria elétrica. Escória A no sistema óxido CaO-SiO2-MgO-Al2O3-CaF2 (CSMA-F) e escórias B e C no sistema óxido CaO-SiO2-MgO-Al2O3 (CSMA) foram analisadas. Duas amostras de aço foram coletadas em ambiente industrial: forno panela e barra laminada. ASPEX Explorer foi utilizado para obter informações sobre as inclusões, organizando-as por composição química, tamanho, densidade e tipo. FactSage v7.2 calculou as inclusões formadas durante a solidificação do aço, fração líquida e sólida das escórias e viscosidade da fração líquida. Após o refino secundário, o tipo mais comum de inclusão encontrada foram os aluminatos de cálcio. Na barra laminada, o espinélio foi o tipo de inclusão mais frequente, indicando um possível produto de reoxidação. Sua formação pode ser causada devido a interação com os materiais utilizados no distribuidor e molde. A redução da temperatura também favorece a formação de espinélios, como demonstrado pelo FactSage. As inclusões de espinélio foram analisadas pelo método Função de Densidade Populacional (PDF), que identificou que as corridas A1, A2, C1 e C2 apresentavam inclusões de espinélio formadas por reoxidação. Uso de escória no sistema CSMA é indicado já que eventos de reoxidação foram diminuídos nas corridas B1 e B2. No entanto, é necessária uma análise mais profunda dos materiais utilizados no distribuidor e molde para melhorar a limpeza do aço SAE 1055.

Oct 1, 2019

By J. Lampke

The superior characteristics of iron ore pellets compared with natural ore and sinter are well known. Due to the higher grade and bulk density they show improved transport and material handling properties. While charging blast furnaces with pellets an increased productivity is realized through pellet?s uniform structure and composition. The increased productivity is caused by a high permeable furnace burden with a decreased coke usage via fuel injection and oxygen enrichment. Therefore, a narrow pellet size distribution and a minimum content -6.3 mm are necessary (Meyer, 1980). The required pellet size distribution can be achieved on the one hand by screening the fired pellets after the induration furnace and recycle the undersized pellets. On the other hand it is possible to produce high quality iron ore pellets with a high degree of sphericity, the important narrow grain size distribution ranging between 9 to 16 mm with high green strength directly in the pelletizing device. To produce high quality green pellets, possibilities and knowledge about adjustments of the pelletizing device are necessary. The paper presents a classification of state of the art pelletizing systems in accordance with the advantages of the pelletizing disc and pelletizing drum in issues like adjustability, green pellet quality, the recycling rate and the space requirement. By a systematization of the influences on pelletizing the common reliance of objectives on influence like pelletizing moisture, disc inclination, rotational speed, mass flow and rim height are given. A variety of industry-proven examples are shown, too. Keywords: Pellet, iron ore, pelletizing, pelletizing disc

Sep 1, 2012

By Yuanbo Zhang, Qian Li, Helei Zhang, Heng Yu, Guanghui Li, Tao Jiang

"Large reserves of specularite iron ores have been found all over the world, which is characterized by high total iron grade, low gangues content, as well as low commercial price. However, it has not been widely used in sinter or pellet production due to its inferior sintering and roasting behaviors. It has shown that the proportion of specularite ores was increased as high as 40%~50% and good results was achieveed by using Composite Agglomeration Process (CAP), an innovative agglomeration process invented by Central South University. But the mineralization of specularite is still unknown during composite agglomeration processing. In this paper, the induration characteristic of specularite ore is studied by simulating CAP in laboratory, as well as microstructure analysis of CAP product. The results show that specularite pellet is mainly indurated through recrystallization of Fe2O3, calcium ferrite within high basicity sinters matrix interweaves with the recrystallized Fe2O3 on the surface of the pellet, which forms an integral microstructure, and ensures high strength of CAP product for ironmaking.IntroductionLarge reserves of specularite iron ores have been found all over the world, especially in Minas Gerais of Brazil, Xuanhua city and Anshan city of China, Elba island of Italy, St.Gotthard of Switzerland, Cumberland of Britannic, and so on. The specularite ores have a smooth surface, as well as a good crystallization and dense texture. When specularite is used to produce pellets, the specularite ore grains are difficult to adhere onto green ball due to its poor ballability. Moreover, specularite pellet requires high roasting temperature over 1300°C [1]. When specularite ore is used in sintering, the permeability of sintering bed gets bad and the quality of sinter is diminished. The practice in a few sintering plants finds that the output and strength of sinter decrease with the increase of specularite proportion, and the consumption of coke increases [2-4]. Therefore, the utilization of specularite has been limited. Composite Agglomeration Process (CAP) is an innovative technology invented by Central South University [5-7]. The process has the following merits: making reasonable utilization of different iron ore resources; improving the quality and output of sinters; manufacturing sinters with low basicity; significantly reducing energy consumption, etc[8-9]. It has been shown that large proportion specularite ores, as high as 40%~50% can be used well by CAP [10], but the mineralization of specularite pellet is still unknown during composite agglomeration processing. In this investigation, the induration characteristics of specularite ore pellets is studied by simulating CAP in laboratory, and the phase composition and microstructure of CAP product are also characterized by using microscope and Leica image analyzer (Germany, Leica DM RXp)."

Jan 1, 2011

By Haragobinda Srichandan

The present study aimed to investigate the bioleaching efficiency of moderate thermophilic microorganism in a growth medium without Fe supplement on three different size fractions of spent catalyst obtained from petroleum refinery. All the experiments were conducted on shake flasks at a temperature of 65 °C and a pulp density of 10% (w/v) on three size fractions viz. 45-106 µm, 106-212 µm and >212 µm and a working volume of 100 ml comprising of 10 ml of microbial inoculums and 90 ml of Modified Kelly medium. The parameters like pH, redox potential, viable planktonic cell count and the amount of acid addition was measured and quantified on regular basis to follow the progress of the bioleaching. The pH varied much in the lag and logarithmic phase of the experiments but stabilized toward the stationary phase. The total acid additions in each batch experiment were determined the amount of Conc. H2SO4 requirement, which ranged between 683-757 kg/ton of spent catalyst. The redox potential values ranged between 625-650 mV, Ag/AgCl, but were very low ranging between 350-450 mV during initial period. The planktonic viable cell count ranged between 108-109 cells/ml active in the bioleaching system, without any toxic influence of the spent catalyst, but initially due to fall in redox potential and new environment for the microbes, their population was low. The leaching yield of Ni was found to be promising with very high leaching yield of 92-96% followed by Al as 61-62%, which means both Ni and Al leaching were favored by the moderate thermophilic bioleaching compared to the mesophilic bioleaching. There was very little difference in the leaching yield, when compared with different size fractions and hence grinding can be avoided prior to leaching. This process seems to be economical as no Fe source is supplemented together with no requirement of grinding and over all a biological process resulting for an eco-friendly process for future optimization of the metal recovery from petroleum refinery spent catalysts. Keywords: bioleaching, spent catalyst, thermophile, 9K medium

Sep 1, 2012

By I. Caraconcea, M. Cousineau, S. Gariepy

"Several base metal plants operate in low grade/high tonnage conditions which impose strict cost control on all fronts for their operations to remain profitable. This leads to decisions regarding plant design, procurement, operations and maintenance that often favor cost minimization over value optimization. This may hinder the representativeness of the metal accounting systems while this should be a priority in a low margin environment. Such poor representativeness not only creates confusion in plant scheduling but can also hide suboptimal metallurgical performance. Furthermore, this situation can run undetected for a while since one dominant feature of a poor metal accounting system is its poor self-awareness. During their practice, authors have particularly identified measurement bias and reproducibility, as well as their impact on metal recoveries as areas of concern. These issues have not been extensively reviewed in the specific context of precious metals in base metal plants. Pragmatic solutions are proposed either at the design stage for a new project or to retrofit an actual operation. These solutions should be based on a business analysis that set a value of information matching the contribution of precious metals as well as the potential to use such information to act toward increasing plant profitability. Conclusions are that trade-offs are an inherent part of the design/audit/retrofit of any metal accounting system in any plant processing either base or precious metals. However, compromises must be evaluated on economic/technical ground.INTRODUCTION Every mineral processing plant must produce metal accounting reports (Morrison, 2008) where estimated saleable metal flows and inventories are published. These metal accounting reports are delivered to a variety of stakeholders who use them for internal management purposes (day-to-day plant production planning, plant operation optimization, capital spending, etc.) as well as for external management (royalty settlements, tolling agreements, etc.). Hence, there should be no doubt that state of the art metal accounting is instrumental for mining companies to reach and sustain high-quality corporate governance (Gaylard, Randolph, & Wortley, 2014). However, producing a metal accounting report involves much more than just printing it (Lachance, Leroux, & Gariépy, 2015a). The underlying metal accounting system (Figure 1) is responsible not only for the reliable production of the metal accounting reports but also for the quality of the outcome. As such, the crucial tasks of its design/audit/retrofit should neither be seen as ancillary nor be left as an afterthought."

Jan 1, 2017

By R. E. Turner

Hamersley Iron Pty. Limited, one of the world's largest iron ore producers, operates a 3.0 million tonne per year pelletizing facility at Dampier in Western Australia. The plant produces pellets for the export market using a blend of natural hematite fines from the Company's two mines at Tom Price and Paraburdoo. Processing includes fluidised-bed drying of the ore feed, open circuit dry grinding, disc balling and pellet induration in a travelling grate furnace of Dravo-Lurgi design.

Jan 1, 1980

The Canadian concept for nuclear fuel waste disposal is being assessed by AECL Research in a series of experiments at its Underground Research Laboratory (URL) near Lac du Bonnet. Manitoba, Canada. As pan of this research, the Mine-by Experiment has been designed to obtain information on rock mass behavior, the development of an excavation-induced damage zone and failure mechanisms around a circular bored tunnel. An iterative design approach was used to effectively reconcile the experiment objectives and construction logistics. This paper discusses the design considerations and construction methodology adopted on the project.

Jan 1, 1991

By Elimame Elaloui, Kais Elghniji, Constantin Virlan, Aurel Pui, Chaima Ouled Amor

Separation and identification of minerals composing the Tunisian silica sands have been conducted by acid etching and hot filtration/sedimentation (HFS) without affecting the quartz component. It was found that the hot acid etching process is an effective method to separate quartz and clay minerals in the silica sand. The SEM micrographs of the silica sand show rough surface and some cracks with irregular shapes. The surface becomes clean and smooth after acid etching process. After chemical dissolution, the clay minerals were recovered by hot filtration following by sedimentation at low temperature. FT-IR, EDS maps, and secondary electron (SE) analyses of separated clay minerals reveal the presence of Fe2O3, montmorillonite, and kaolinite minerals. The LIBS analysis of clay minerals shows the presence of Al, Fe, Ca, Al, and Mg. The sequential etching process can be introduced in the purification methods as an effective way to separate quartz from clay minerals.

Jul 29, 2020