Jovanovic, Vladimir

KANARI, Ndue

Kojic, Marija

Martinovic, Sanja

Milicevic, Sonja

Popovic, Ana

Vlahovic, Milica

Kanari, Ndue

HAL Descartes

Development and mechanical properties of the pelletized fly ash

HAL-INSU

Hal-Diderot

This paper covers the results of pelletizing fly ash in order to obtain pellets, with satisfied mechanical properties, that can be used in wastewater treatments. Serbian fly ash from
“Nikola Tesla” power plant was used as a low cost sorbent. Fly ash was subjected to elementary
and XRD analysis. Portland cement was used as a pelletizing agent along with the plastification agent. The mechanical properties of pellets were investigated using different methods such as: pressure resistance, impact resistance, resistance to abrasion, and disintegration in water. The best results were obtained with the addition of 10 % of cement along with the plasticizer

Milićević, Sonja

Martinović, Sanja

Jovanović, Vladimir

Vlahović, Milica

Popović, Ana

Kojić, Marija

Central Repository of the Institute of Chemistry, Technology and Metallurgy (CER)

UNIVERSITY OF BELGRADETECHNICAL FACULTY IN BORCHAMBER OF COMMERCE ANDINDUSTRY OF SERBIAXIII InternationalMINERAL PROCESSING andRECYCLING CONFERENCEEditors:Grozdanka BogdanovićMilan TrumićPROCEEDINGSBelgrade, Serbia, 8 – 10 May 2019 UNIVERSITY OF BELGRADE TECHNICAL FACULTY IN BOR    CHAMBER OF COMMERCE AND INDUSTRY OF SERBIA     PROCEEDINGS        XIII INTERNATIONAL MINERAL PROCESSING and RECYCLING CONFERENCE     Editors: Grozdanka Bogdanović Milan Trumić     Belgrade, Serbia, 8 – 10 May 2019 XIII INTERNATIONAL MINERAL PROCESSING and RECYCLING CONFERENCE  PUBLISHER University of Belgrade, Technical Faculty in Bor  FOR THE PUBLISHER DEAN: Prof. Dr Nada Štrbac  EDITORS Prof. Dr Grozdanka Bogdanović  Prof. Dr Milan Trumić  PROCEEDINGS COVER DESIGN Predrag Stolić  PRINTED BY Grafomed Trade doo, Bor, Serbia    Printed: 200 copies   CIP – Каталогизација у публикацији  Народна библиотека Србије, Београд                 ISBN 978-86-6305-091-4                             Conference is financially supported by Republic of Serbia,                 Ministry of Education, Science and   Technological   Development  XIII International Mineral Processing and Recycling Conference, Belgrade, Serbia, 8-10 May 2019 v INTERNATIONAL SCIENTIFIC COMMITTEE Prof. Dr Milan Trumić (Serbia), President Prof. Dr Grozdanka Bogdanović (Serbia), Vice President Prof. Dr Takashi Nakamura (Japan) Prof. Dr Przemyslaw Boguslaw Kowalczuk (Norway) Prof. Dr Rraghupatruni Bhima Rao (India) Prof. Dr Hojae Shim (China) Prof. Dr Junbeum Kim (France) Prof. Dr Veena Sahajwalla (Australia) Prof. Dr Georgios N. Anastassakis (Greece) Prof. Dr Vasilis Fthenakis (USA) Prof. Dr Jakob Lamut (Slovenia) Dr Florian Kongoli (Canada) Prof. Dr Ivan Nishkov (Bulgaria) Prof. Dr Ofira Ayalon (Israel) Prof. Dr Ilhan Bušatlić (Bosnia & Herzegovina) Prof. Dr Adele Muscolo (Italy) Dr Evangelos Gidarakos (Greece) Prof. Dr Cipriana Sava (Romania) Prof. Dr Alejandro Rodriguez Pascual (Spain) Dr Stojan Simić (Bosnia & Herzegovina) Prof. Dr Zdenka Zovko Brodarac (Croatia) Dr Slavomir Hredzak (Slovakia) Prof. Dr Irena Grigorova (Bulgaria) Prof. Dr Vladimir Čablik (Czech Republic) Prof. Dr Nada Štrbac (Serbia) Prof. Dr Dejan Tanikić (Serbia) Prof. Dr Milan Antonijević (Serbia) Prof. Dr Vlada Veljković (Serbia) Prof. Dr Zoran Stević (Serbia) Prof. Dr Mira Cocić (Serbia) Prof. Dr Jovica Sokolović (Serbia) Prof. Dr Goran Vujić (Serbia) Prof. Dr Željko Kamberović (Serbia) Prof. Dr Miodrag Žikić (Serbia) Prof. Dr Milena Kostović (Serbia) XIII International Mineral Processing and Recycling Conference, Belgrade, Serbia, 8-10 May 2019 vi Prof. Dr Ljubiša Andrić (Serbia) Prof. Dr Dušan Stanojević (Serbia) Prof. Dr Marina Stamenović (Serbia) Prof. Dr Mile Dimitrijević (Serbia) Prof. Dr Dejan Ubavin (Serbia) Doc. Dr Zoran Štirbanović (Serbia) Doc. Dr Maja Trumić (Serbia) Doc. Dr Vladimir Pavićević (Serbia) Doc. Dr Vladimir Despotović (Serbia) Dr Miroslav Ignjatović (Serbia) Dr Zoran Stevanović (Serbia) Dr Dragan Milanović (Serbia) Dr Dragan Radulović (Serbia) Dr Sonja Milićević (Serbia) Dr Radmila Marković (Serbia) ORGANIZING COMMITTEE Prof. Dr Grozdanka Bogdanović (Serbia), President Prof. Dr Milan Trumić (Serbia) Dr Miroslav Ignjatović (Serbia) Prof. Dr Jovica Sokolović (Serbia) Doc. Dr Zoran Štirbanović (Serbia) Doc. Dr Maja Trumić (Serbia) M.Sc. Aleksandra Stojanović (Serbia)M.Sc. Vladimir Nikolić (Serbia)M.Sc. Dragana Marilović (Serbia)M.Sc. Predrag Stolić (Serbia)B.Sc. Katarina Balanović (Serbia)Sandra Vasković, English language teacher (Serbia) Dobrinka Trujić (Serbia)# corresponding author: s.milicevic@itnms.ac.rs XIII International Mineral Processing and Recycling Conference Belgrade, Serbia, 8-10 May 2019 University of Belgrade, Technical Faculty in Bor Vojske Jugoslavije 12, 19210 Bor, Serbia Tel. +381 30 424 555 Fax +381 30 421 078 DEVELOPMENT AND MECHANICAL PROPERTIES OF THE PELLETIZED FLY ASH Sonja Milićević 1, #, Sanja Martinović 2, Vladimir Jovanović 1,        Milica Vlahović 2, Ndue Kanari 3, Ana Popović 1, Marija Kojić 2 1Institute for Technology of Nuclear and Other Mineral Raw Materials, Belgrade, Serbia 2University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Belgrade, Serbia 3Université de Lorraine, UMR 7359 CNRS, CREGU, GeoRessources Laboratory, 2, rue du doyen Roubault, BP 10162,  54505 Vandoeuvre-lès-Nancy, France ABSTRACT – This paper covers results of pelletizing fly ash in order to obtain pellets, with the satisfied mechanical properties, that can be used in wastewater treatments. Serbian fly ash from “Nikola Tesla” power plant was used as a low cost sorbent. Fly ash was subjected to the elementary and XRD analysis. Portland cement was used as pelletizing agent along with the plastification agent. Mechanical properties of pellets were investigated using different methods such as: pressure resistance, impact resistance, resistance to abrasion and disintegration in water. Best results were obtained with addition of 10 % of cement along with the plasticizer.  Key words: fly ash, pellets, mechanical properties. INTRODUCTION Recent investigations are focused on possibility of waste utilization as potential adsorbents in wastewater treatments. Industrial by-products and wastes are almost zero-cost materials and at the same time their utilization could contribute to the solution of their management problem improving the material efficiency within the several industrial activities.  Fly ash has potential application in wastewater treatment because of its major chemical components (alumina, silica, ferric oxide, calcium oxide, magnesium oxide and carbon), and its physical properties such as porosity, particle size distribution and surface area. Besides, the alkaline nature of fly ash makes it a good neutralizing agent [1, 2]. Namely, fly ash as a potential hazardous solid waste produced like a by-product in power plants worldwide in million tonnes has attracted researches XIII International Mineral Processing and Recycling Conference, Belgrade, Serbia, 8-10 May 2019  39 interest for years. Fly ash material solidifies while suspended in the exhaust gases and is collected by electrostatic precipitators or filter bags. Since the particles solidify rapidly while suspended in the exhaust gases, fly ash particles are generally spherical in shape and range in size from 0.5 µm to 300 µm.  Therefore, the hydraulic properties of fly ash are the one that present major obstacle for its application in wastewater treatments. The problem of micronized fly ash particles that are not useful in wastewater treatments can be overcome through the agglomeration process such as pelletization. Pelletization is a form of tumble growth agglomeration, whereby material fines are “grown” through a tumbling motion and the addition of water or a binding agent [3]. This process is a non-pressure method of agglomeration that allows production of new materials and use of waste resources with significant environmental and economic impact. This paper is focused on processing and valorization of industrial waste - fly ash in order to obtain new adsorption material with good mechanical properties and removing capacity for heavy metals from acid mine wastewaters.   EXPERIMENTAL  Materials  Fly ash originates from power plant Nikola Tesla (Tent B) and the chemical composition is presented in Table 1.  Table 1. Chemical composition of the fly ash Content (%) SiO2 Al2O3 Fe2O3 CaO MgO K2O Na2O TiO2 47.80 30.53 5.47 8.69 2.29 1.49 0.25 1.02 Cd Pb Zn Cu Cr Ni Mn IL* 0.005 0.04 0.021 0.005 0.022 0.03 0.045 1.45 IL * - Ignition lost  Chemical composition places the investigated fly ash to the class F that is characterized with pozzolanic properties. The mineralogical composition of fly ash was primarily quartz with small amounts of mullite and plagioclase as determined by X-ray powder diffraction analysis (Philips, PW-1710). Particle size distribution (Figure 1), determined using laser diffraction method (Helos (H1597) & Sucell R4, Sympatec GmbH) show the major size fraction mass content (60 %) of the class below 100 µm. Cement used in these investigations belong to group of Portland cement and is produced by the Lafarge (PC 42.5R Lafarge). Plasticizer is applied as chemical additive with a purpose to absorb on the cement particles and build the network of the cement particles. Plasticizer used in this paper belongs to the group of the highly efficient superplasticizer (hyperplasticizer) Cementol Hiperplast 463, produced by the TKK, Slovenia. The effect of the plasticizer depends, mainly, on the type and the amount of the cement. Frame dose of the plasticizer is 0.2 - 1.5 kg plasticizer / 100 kg cement. The mixing XIII International Mineral Processing and Recycling Conference, Belgrade, Serbia, 8-10 May 2019  40 time, after the addition of the plasticizer should be at least 1 min, where the optimal time is 3 min.   Figure 1. Particle size distribution of the fly ash  Table 2. Chemical composition of the Portland cement Content (%) SiO2 Al2O3 Fe2O3 CaO MgO K2O Na2O P2O5 21.10 5.42 2.38 63.18 2.35 0.74 0.23 0.12 SO3 < 4 % Cl Na2Oeq ZnO Mn2O3 SrO TiO2 / 3.56 0.0386 0.72 0.038 0.11 0.099 0.245 /  Pelletization  Fly ash pelletizing was conducted on ’’Ünal’’ disc pelletizer with vibratory feeder, (plate diameter 40 cm, edge height 10 cm, plate inclination angle of 50 °, rotary speed 15 rpm).  The initial samples of fly ashe and cement were homogenized. This is a precondition that must be met in order to obtain pellets of uniform composition during pelletizing. Fly ash is homogenized with the required amount of cement as a binder, without adding any water. After that, the homogenized samples are by vibratory feeder continuously fed on to the pelletizing plate, where the necessary amount of water is added using sprayers. During pelletizing experiments, in some samples, precisely defined amount of plasticizer was added, also. The plate inclination angle (50 °) and the number of revolutions (15 rpm) were constant, while the quantity of the binder varied. Four composite samples were formed by mixing Fly ash, cement as binder and plasticizer with the Fly ash to cement mass ratio presented in Table 3.  Table 3. Content of the materials used for the production of pellets Mark Fly ash Cement Plasticizer P10p 90 % 10 % 0.15 ml P10 90 % 10 % / P5p 95 % 5 % 0.07 ml P5 95 % 5 % / 0204060801001,00 10,00 100,00 1000,00M (%)Particle size distribution (mm)XIII International Mineral Processing and Recycling Conference, Belgrade, Serbia, 8-10 May 2019  41 Number next to the letter P indicates the percentage of the cement in the sample and the presence of letter ‘’p’’ in subscript implies the addition of the plasticizer.  Formed pellets were stored for 72 h at the 90 % moisture saturated atmosphere and then dried at 40 °C .  RESULTS AND DISCUSSION  After drying process, pellets were sieved and four different fraction sizes were obtained, as presented in Figure 2.    Figure 2. Different fraction sizes of the obtained pellets  Particle size distribution, presented in Figure 3, indicate the largest presence (41 %) of the class - 2.0 + 1.0 mm. This particle size along with the class of - 3.35 + 2.0 mm (17 %) and class of - 7.0 + 3.35 mm (24 %) are the preferred size of the pellets for their application in the dynamic (column) systems. The percentage of the undesirable class of - 1.0 mm below 20 % is a very good result.   Figure 3. Particle size distributions of the pellets  The purpose of fly ash pelletization, in this paper, is to obtain the material that is more suitable for the application in the wastewater treatments than the parenting one (micronized fly ash). In generally, the pellets are produces to improve the 18%41%17%24%0.00-1.00 mm1.00-2.00 mm2.00-3.35 mm3.35-7.00 mmXIII International Mineral Processing and Recycling Conference, Belgrade, Serbia, 8-10 May 2019  42 hydraulic properties of the fly ash. However, from the transport and handling point of view, there are certain mechanical properties that pellets need to satisfy. Tests for pellet mechanical properties include: impact resistance, compressive strength, abrasion resistance and the time required for the pellet to disintegrate completely in water. Impact resistance is tested by dropping a 100 g pellet sample 25 times from the height of 457 mm on to a 9 mm thick steel plate, after which the sample is sieved on a corresponding screen, whereat the mass of screen undersize should not exceed 5 % (more rarely 10 %) of the total mass of the sample [4]. Obtained results are presented in Table 4.  Table 4. Dependence of the pellets impact resistant on binder content 1.0 - 2.0 mm 2.0 - 3.35 mm 3.35 - 7.0 mm % P10p 10.5 9.3 9.2 P10 19.3 16.1 14.6 P5p 65.8 47.1 34.6 P5 81.1 78.3 75.4   According to the results, the dosage of the binder and the addition of the plasticizer, both, highly influence this mechanical property of the pellets. Only pellets with the 10 % of cement and addition of plasticizer meet the requested demand for this mechanical property.  Compressive strength is tested on 10 pellet samples using a standard laboratory hydraulic press in order to determine the maximum pressure that the pellet can withstand without breaking. Pellets should be able to withstand a minimum of 0.5 kg/pellet, which is considered as satisfactory for further handling [4]. Obtained results are presented in Table 5.   Table 5. Dependence of the pellets compressive strength on binder content 1.0 - 2.0 mm 2.0 - 3.35 mm 3.35 - 7.0 mm kg/pеllet P10p 0.45 0.60 1.12 P10 0.32 0.51 0.73 P5p 0.15 0.32 0.45 P5 0.09 0.15 0.21  From the results in Table 5 it’s obvious that the dosage of the cement highly influences this property. Pellets with 10 % of cement, regardless the addition of plasticizer, mostly meet the requested demand, and the compressive strength increases with increasing the particle size.  Pellet abrasion resistance is tested by sieving a 100 g pellet sample on a laboratory mechanical device, i.e., a corresponding screen, for a period of 5 min. After that it was possible to determine that the mass fraction of screen undersize should not exceed 5 % of the total mass of the sample [4]. Obtained results are presented in Table 6. XIII International Mineral Processing and Recycling Conference, Belgrade, Serbia, 8-10 May 2019  43 Table 6. Dependence of the pellets abrasion resistance on the binder content 1.0 - 2.0 mm 2.0 - 3.35 mm 3.35 - 7.0 mm P10p 0.52 3.13 3.17 P10 1.59 4.86 4.98 P5p 2.65 17.5 11.95 P5 5.2 21.3 25.4   Pellets with 10 % of cement, regardless the addition of plasticizer and particle size distribution meet the requested demands.  The disintegration of pellet in water is tested by immersing three pellet samples from each group into the water, at room temperature and measuring the time required for the pellet to completely disintegrate in water. Obtained results are presented in Table 7.   Table 7. Average time required for pellets to disintegrate in water depending on binder dosage 1.0 - 2.0 mm 2.0 - 3.35 mm 3.35 - 7.0 mm h P10p 0.52 3.13 3.17 P10 1.59 4.86 4.98 P5p 2.65 17.5 11.95 P5 5.2 21.3 25.4  All investigated pellets, regardless the cement dosage, addition of plasticizer and the particle size distribution meet this demand.  CONCLUSION  Fly ash can be efficiently pelletized using cement as binder. Under the investigated pelletizing conditions, more than 80 % of the obtained pellets are suitable for the application in continuous systems, from the particle size distribution point of view. For the production of the pellets with the satisfying mechanical properties, required amount of the cement as binder is 10 %. The dose of the plasticizer, up to 3 % in relation to the amount of the cement, additionally improves the mechanical properties, especially impact resistance.  Acknowledgements:  This research has been part of the investigations on the bilateral project N° 40808RM (project registration number: 451-03-01963/2017-09/08) between the France and Serbia (Pavle Savic program). It has been financed by the Ministry of Education, Science, and Technological Development of Republic of Serbia as part of the project TR 033007 “Implementation of new technical, technological and environmental solutions in the mining and metallurgical operations RBB and RBM”. Part of the investigations were financially supported through the ‘’Green fond’’ financed by the Ministry of Environmental Protection of Republic of Serbia. The authors would like to express their gratitude for this support.  XIII International Mineral Processing and Recycling Conference, Belgrade, Serbia, 8-10 May 2019  44 References  1. Milicevic, S., Boljanac, T., Martinovic, S., Vlahovic, M., Milosevic, V., Babic, B. (2012) Removal of copper from aqueous solutions by low cost adsorbent-Kolubara lignite. Fuel Processing Technology, 95, 1-7, 2. Papandreou, A., Stournars, C. J., Panias, D. (2007) Copper and cadmium adsorption on pellets made from fired coal fly ash.  Journal of Hazardous Materials, 148 (3), 538-547, 3. Mehos, G., Kozicki, C. M. (2017) Choosing agglomeration equipment. Chemical Engineering, 124 (10), 51-57, 4. Albert, K. B., Langford, D. (1998) Pelletizing limestone fines, Mars Mineral, Mars, PA,  12-29, 5. Jovanović, V., Knežević, D., Dekulić, Ž., Kragović, M., Stojanović, J., Mihajlović, S., Nišić, D., Radulović, D., Ivošević, B., Petrov, M. (2017) Effects of bentonite binder dosage on the properties of green limestone pellets. Hemijska Industrija, 71 (2), 135-144. 

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Development and mechanical properties of the pelletized fly ash

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Central Repository of the Institute of Chemistry, Technology and Metallurgy (CER)