scholarly journals Synthesis of Fly Ash-Based Geopolymers: Effect of Calcite Addition and Mechanical Activation

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 827 ◽  
Author(s):  
Alexander M. Kalinkin ◽  
Basya I. Gurevich ◽  
Mikhail S. Myshenkov ◽  
Mikhail V. Chislov ◽  
Elena V. Kalinkina ◽  
...  
Keyword(s):  
Fly Ash ◽  
Mechanical Activation ◽  
Sodium Hydroxide Solution ◽  
Planetary Mill ◽  
Raw Material ◽  
Mass Spectrometry Analysis ◽  
Activation Time ◽  
Evolved Gas ◽  
Spectrometry Analysis ◽  
Alkaline Agent

Blends of fly ash and natural calcite, mechanically activated for 0–400 s in a planetary mill, were used to synthesize geopolymers at ambient temperature. The calcite content in the blends was 0–10 wt.%. Sodium hydroxide solution was used as an alkaline agent. Mechanical activation of the raw material considerably enhanced its reactivity with respect to the alkaline agent, as was observed using Fourier-transform infrared spectroscopy, isothermal conduction calorimetry, thermogravimetry coupled with mass spectrometry analysis of the evolved gas, and SEM/EDS. The addition of calcite to the fly ash improved the compressive strength of the geopolymers, especially during the early age of curing. For 7 d aged geopolymers based on the 90% fly ash + 10% calcite blend, the strength was 8.0-, 3.5- and 2.9-fold higher than that for the geopolymers based on the unblended fly ash for 30 s, 180 s and 400 s mechanical activation time, respectively. Using Mössbauer spectroscopy, it was revealed that iron present in the fly ash did not play a significant part in the geopolymerization process. The dominant reaction product was sodium containing aluminosilicate hydrogel (N-A-S-H gel). Calcite was found to transform, to a small extent, to vaterite and Ca(OH)2 in the course of the geopolymerization.

scholarly journals Geopolymers Based on Mechanically Activated Fly Ash Blended with Dolomite

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 700
Author(s):  
Alexander M. Kalinkin ◽  
Basya I. Gurevich ◽  
Elena V. Kalinkina ◽  
Mikhail V. Chislov ◽  
Irina A. Zvereva
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Mechanical Activation ◽  
Raw Material ◽  
Early Age ◽  
X Ray Diffraction ◽  
Simple Method ◽  
X Ray ◽  
Alkaline Agent ◽  
Naoh Solution

This study reports the effect of natural dolomite addition to fly ash and the mechanical activation of this blend on the geopolymerization process. Dolomite was replaced with fly ash at 1, 3, 5, and 10 wt.%. Geopolymers were synthesized at ambient temperature using NaOH solution as an alkaline agent. The geopolymerization process, reactivity of the raw material, compressive strength, and microstructure were studied using X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetry, and scanning electron microscopy. It was shown that blending fly ash with dolomite and mechanical activation improved the geopolymer strength, especially during the early age of curing. For geopolymers prepared using a 90% fly ash + 10% dolomite blend cured for 7 d, the strengths were 8.2-, 2.3-, and 1.4-fold higher than those for geopolymers prepared using 100% FA for 30 s, 180 s, and 400 s milling times, respectively. A simple method for evaluating the increments of mechanical activation, carbonate additives, and the synergistic effect in the increase in the compressive strength of the composite geopolymer is proposed.

scholarly journals Preparation of fly ash-based flocculant and flocculation performance

2021 ◽  
Vol 2079 (1) ◽  
pp. 012006
Author(s):  
Junxin Zhang ◽  
Xiumei Duan
Keyword(s):  
Fly Ash ◽  
Sodium Carbonate ◽  
Thermal Power ◽  
Liquid Product ◽  
Acid Leaching ◽  
Raw Material ◽  
Molar Ratio ◽  
Activation Time ◽  
Activation Temperature ◽  
Preparation Conditions

Abstract Using fly ash from a thermal power plant in Yingkou City as raw material, The inorganic polymer flocculant polyaluminum ferric chloride (PAFC) was prepared by sodium carbonate impregnation, high temperature roasting activation, and acid leaching. The influence of activation temperature and activation time on the leaching of aluminum and iron was investigated through single factor test and orthogonal test. The PAFC preparation conditions were optimized, and the prepared PAFC flocculant product was applied to kaolin turbidity water. The test results showed that the content of aluminum in fly ash was 7.08%, and the content of iron was 4.95%. The mass ratio of the activator sodium carbonate and fly ash was 10:7, the activation temperature was 800°C, and the activation time was 2h. The leaching rates of aluminum and iron were the highest, 88.31% and 53.66% respectively. The optimal conditions for the preparation of the flocculant were as follows: the molar ratio of aluminum to iron was 5.7:1, and the reaction time was 1.5h. The liquid product obtained under these conditions was yellowish brown, and the solid product obtained after being dried was yellow powder.

Effect of Mechanical Activation of Fluidized Bed Fly Ash on Geopolymer Properties

2019 ◽  
Vol 288 ◽  
pp. 51-58
Author(s):  
Gendenjamts Oyun-Erdene ◽  
Jadambaa Temuujin
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Mechanical Activation ◽  
Sodium Hydroxide ◽  
Fluidized Bed ◽  
Sodium Silicate ◽  
Sodium Hydroxide Solution ◽  
Chemical Activation ◽  
Weight Ratio ◽  
Particle Size Reduction

This paper is focused on the elucidation of mechanical activation effect of circulating fluidized bed combustion fly ash (Amgalan Thermal Station, Mongolia) on mechanical properties of geopolymers. Fluidized bed fly ash was mechanically activated for 15-120 minutes with a vibratory mill. The effect of mechanical activation was quite visible on the particle size reduction and on the degree of amorphization.Geopolymer samples were prepared from the raw and milled fluidized bed fly ashes by alkaline activation. Chemical activation was performed with 10M sodium hydroxide solution, as well as solutions containing a mixture of sodium silicate and sodium hydroxide with a weight ratio of 2:1. The geopolymer cubic specimens were cured at 70°C for 24 hrs and their 7 days uniaxial compressive strength was measured. After curing and drying, the bulk density, water absorption and apparent porosity of geopolymer samples were evaluated.X-ray powder diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetry-differential thermal analysis (TGA-DTA) have been used for the structural characterization of the CFA and the resulting geopolymers. The highest compressive strength of 32.4 MPa was achieved for the fly ash milled for 30 minutes and activated with the solution containing the sodium silicate and 10M sodium hydroxide at a weight ratio of 2:1. Non-milled CFA based geopolymers showed the compressive strength of 16.2 MPa after activation with the same solution. Mechanical activation resulted in an increase in the reactivity of the fluidized bed fly ash and that enhances the geopolymerization reactions.

Effect of Mechanical Activation on the Synthesis of Ba-Celsian and Sr-Celsian using Precursor Mixtures Containing Coal Fly Ash

2016 ◽  
Vol 1812 ◽  
pp. 89-94
Author(s):  
Claudia M. Lopez-Badillo ◽  
Jorge López-Cuevas ◽  
Carlos A. Gutiérrez-Chavarría ◽  
José L. Rodríguez-Galicia ◽  
Elia M. Múzquiz-Ramos
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Solid State ◽  
Mechanical Activation ◽  
Solid State Reaction ◽  
Milling Time ◽  
Coal Fly Ash ◽  
Raw Material ◽  
Attrition Mill ◽  
Sintered Materials

ABSTRACTBaAl2Si2O8 and SrAl2Si2O8 were synthesized by solid-state reaction of stoichiometric mixtures of either BaCO3 or SrCO3 with coal fly ash and Al2O3. The mixtures were mechanically activated in an attrition mill for up to 12 h and then reaction-sintered at 900-1300 °C, aiming to promote the formation of BaAl2Si2O8 and SrAl2Si2O8 as well as the conversion from their hexagonal (Hexacelsian) into their monoclinic (Celsian) forms, which is associated with improved mechanical properties in the sintered materials. Especially in the case of SrAl2Si2O8, the formation of Celsian was favored at relatively low sintering temperatures by increasing milling time. Although only the SrAl2Si2O8 composition was fully converted into Celsian, the Hexacelsian to Celsian conversions obtained for the mechanically-activated BaAl2Si2O8 composition were significantly higher than those previously reported in the literature for this compound. This could be attributed to the use of coal fly ash as raw material, which contains mineralizers that promote the mentioned conversion.

EFFECT OF MECHANICAL ACTIVATION AND CURING MODES ON STRENGTH OF FLY ASH BASED GEOPOLYMERS

2020 ◽  
pp. 38-42
Author(s):  
E. V. Kalinkina ◽  
◽  
B. I. Gurevich ◽  
A.M. Kalinkin ◽  
A.G. Ivanova ◽  
...  
Keyword(s):  
Fly Ash ◽  
Power Plant ◽  
Mechanical Activation ◽  
Sodium Hydroxide ◽  
Thermal Power Plant ◽  
Sodium Hydroxide Solution ◽  
Thermal Power ◽  
Hydroxide Solution ◽  
Hydrothermal Curing

The problems of increasing the reactivity of fly ash of the Apatity thermal power plant in the reactions of geopolymerization occurring under the influence of mechanical activation were considered. The effect of the normal and hydrothermal curing of fly ash activated with sodium hydroxide solution on the strength of the resulting geopolymers was studied.

Isotope Exchange between 18O2 Gas and Mechanoactivated Oxide NdMnO3+δ

2013 ◽  
Vol 333 ◽  
pp. 193-198 ◽  
Author(s):  
O.M. Fedorova ◽  
Anatoly Yakovlevich Fishman ◽  
Tatiana Eugenievna Kurennykh ◽  
Vladimir Borisovich Vykhodets ◽  
V.B. Vykhodets
Keyword(s):  
Mechanical Activation ◽  
Isotope Exchange ◽  
Mechanical Treatment ◽  
Isothermal Annealing ◽  
Planetary Mill ◽  
Ceramic Technology ◽  
Activation Time ◽  
Graaff Accelerator ◽  
Nuclear Microanalysis ◽  
Exchange Parameters

sotope exchange of oxygen 18О2 with oxides NdMnO3+δ was investigated. The oxide was obtained from oxides Nd2O3 and Mn2O3 using a ceramic technology with annealing in air at 1400°C for 90 hours followed by cooling in a furnace. A planetary mill AGO-2 with a centrifugal factor of g = 60 was used for mechanical treatment of oxides. The study of isotope exchange was carried out by nuclear microanalysis. The concentration of the isotopes 18O and 16O in oxides was determined using a Van de Graaff accelerator and 18O(p, α)15N and 16O(d, p)17O* reactions at the energies of incident beams 762 and 900 keV. Isothermal annealing of powders was carried out in oxygen, enriched to 80% by the isotope 18O. It was established that the concentration of the isotope 18O in mechanically activated powders was several times higher than in the initial micropowder under the same conditions of annealing. The effect increased with increasing of mechanical activation time (30 - 300 s). The isotope exchange parameters connected with the processes at the boundaries of the particles of mechano-activated powder and within their volume were analyzed.

scholarly journals Geopolymers Based on Mechanically Activated Fly Ash Blended with Dolomite

2021 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
Alexander M. Kalinkin ◽  
Basya I. Gurevich ◽  
Elena V. Kalinkina ◽  
Mikhail V. Chislov ◽  
Irina A. Zvereva
Keyword(s):  
Fly Ash ◽  
Mechanical Activation ◽  
Construction Industry ◽  
Coal Combustion ◽  
Energy Savings ◽  
Thermal Power ◽  
Planetary Mill ◽  
Power Station ◽  
Industrial Plants ◽  
Naoh Solution

Man-made deposits of fly ash (FA)—a solid by-product of coal combustion—accompany practically every thermal power station and many industrial plants. The total annual production of FA worldwide is about seven–eight hundred million tons, of which less than one third is recycled. The accumulated FA has become a problem for the environment due to its heavy metal content, which can be leached out. The mineral composition of FA is mainly represented by the glass phase and also by quartz, mullite, magnetite and other minerals. In the last decade, intensive studies have been carried out on the use of FA for the preparation of geopolymer materials. Due to their energy savings, environmentally friendly processing and high physical-mechanical properties, geopolymers are gaining attention in the construction industry as a potential replacement for Portland cement. In this work, we focused on the effect of natural dolomite addition to FA and mechanical activation of this blend on the geopolymerization process. The influence of dolomite dosage and duration of mechanical activation in a planetary mill on the reactivity of the blend in relation to NaOH solution and on the geopolymer compressive strength was studied.

Study on Activated Carbon Prepared from Coking Fly Ash with KOH Activation

2012 ◽  
Vol 490-495 ◽  
pp. 3540-3544
Author(s):  
Shu Guang Ouyang ◽  
Le Le Fu ◽  
Zhi Wang
Keyword(s):  
Activated Carbon ◽  
Fly Ash ◽  
Carbon Material ◽  
Total Pore Volume ◽  
Absorption Capacity ◽  
Raw Material ◽  
Koh Activation ◽  
Activation Time ◽  
Activation Temperature ◽  
Temperature Activation

An orthogonal experiment is conducted to study the effect of activation temperature, activation time and the ratio of KOH to carbon material (i.e. the mass ratio of KOH to coking fly ash) on the adsorption capacities of the activated carbon made by using coking fly ash as the raw material and KOH the activating agent. The results show that the three factors can be ordered as activation temperature, activation time and the ratio of KOH to carbon material according to the significance in their effect on preparation of activated carbon from coking fly ash. In addition, the optimum activation temperature is 850°C, optimum activation time 30minutes, and the optimum ratio of KOH to carbon material 4:1. For the activated carbon made under these conditions, the iodine absorption capacity is 874.3774mg/g, specific surface-area 275.51m2/g, the mean pore diameter 47.75nm and total pore volume 0.1172cm3/g. As the proportion of mesoporouses reaches 71.57%, the activated carbon made from coking fly ash is good for absorption of those absorbates with higher molecular weights.

Mechanical Activation of Fly Ash by High Energy Planetary Ball Mill and the Effects on Physical and Morphology Properties

2014 ◽  
Vol 625 ◽  
pp. 38-41
Author(s):  
Rashidah Mohammed Hamidi ◽  
Zakaria Man ◽  
Khairun Azizi Azizli ◽  
Lukman Ismail ◽  
Mohd Fadhil Nuruddin
Keyword(s):  
Particle Size ◽  
Fly Ash ◽  
Mechanical Activation ◽  
Ball Mill ◽  
Low Cost ◽  
Specific Area ◽  
High Energy ◽  
Raw Material ◽  
Planetary Ball Mill ◽  
Particle Size Analyzer

Fly ash has a high potential to be converted into geopolymeric material due to its abundant supplies and low cost. However, large particle size of the fly ash caused low reactivity which results in low properties of the end product. The improvement on the fly ash properties by mechanical activation allows it as a new possible raw material in wider application besides solving the low reactivity issue which hindered its range of utilization. In this study, fly ash was mechanically activated by high energy planetary ball mill for 1 hour at different speed, ranging from 100 to 350 rpm and with varied ball to powder ratio (2:1, 3:1 and 4:1). The effects towards its particle size, specific surface area and morphology were determined by particle size analyzer and SEM. It was observed that, increasing of speed to 350 rpm and 4:1 ball to powder ratio (BPR) results in finest size of fly ash where at d (0.1), d (0.5) and d (0.9) the sizes were 1.861, 6.765 and 17.065μm respectively and largest surface specific area (1.46 m2/g).

scholarly journals Conducting materials based on nanodispersed titanium monoxide

2007 ◽  
Vol 39 (3) ◽  
pp. 295-299 ◽  
Author(s):  
A.A. Gusev ◽  
E.G. Avvakumov
Keyword(s):  
Mechanical Activation ◽  
Chemical Resistance ◽  
Lattice Parameter ◽  
Planetary Mill ◽  
The Other ◽  
Titanium Monoxide ◽  
Activation Time ◽  
Ball Size ◽  
Conducting Materials ◽  
Tio2 Rutile

The possibility of obtaining the TiO compound during mechanical activation of rutile and titanium in a planetary mill was studied depending on ball size and the activation time. The initial substances, TiO2 (rutile) and Ti (metal), were shown to change into TiO almost completely during grinding as early as after ten minutes. In this case the cubic modification of TiO formed, with the lattice parameter a=4.185(7) ? and particles of 1-3 ?m, which consisted of units about 10 nm in size. The other subject of our research was the dependence of the conductivity of the products on the conditions under which they were moulded and sintered under argon. The conductivity of the samples was in the range 300 to 600 S cm-1. Their chemical resistance equaled that of Ti4O7 samples.

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