Influence of the Changes of the Structure of Foundry Bentonites on Their Binding Properties

Żymankowska-Kumon, S.; Holtzer, M.; Olejnik, E.; Bobrowski, Andrzej

doi:10.5755/j01.ms.18.1.1342

Cited by 14 publications

(14 citation statements)

References 14 publications

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“…The lost of structural water of bentonite occurred above 500°C. Similar results were also obtained by Zymankowska-Kumon et al (2012). They found that the structure of the smectite completely collapsed due to the lost of structural water at temperature of 700°C.…”

Section: Introductionsupporting

confidence: 83%

“…The basal spacing (d 001 ) of bentonite and heat treated forms as the function of temperature (Table 4) indicates that the temperature slightly alters the basal spacing of the bentonite, however, if the temperature further increases to 600°C, the bentonite structure disappears. As mentioned in the previous section, the temperature has a significant effect on the structural water of the bentonite, the evaporation of structural water will alter the basal spacing of bentonite (Sarikaya et al, 2000;Zymankowska-Kumon et al, 2012). Completely lost of the structural water will destroy the MMt characteristic.…”

Section: Resultsmentioning

confidence: 89%

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Bentonite-hydrochar composite for removal of ammonium from Koi fish tank

Ismadji

Tong

Soetaredjo

et al. 2015

Applied Clay Science

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Section: Introductionsupporting

confidence: 83%

Section: Resultsmentioning

confidence: 89%

Bentonite-hydrochar composite for removal of ammonium from Koi fish tank

Ismadji

Tong

Soetaredjo

et al. 2015

Applied Clay Science

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“…In pure bentonite, peak of kaoline exists in this region, which disappeared after the thermal treatment and substituted with an amorphous band, which indicates the transformation of kaoline to amorphous metakaolinite. Heating the bentonite clay causes its dehydration, which completes at 650 • C and further increase in the temperature leads to its dehydroxylation [25]. The transformation of kaoline to metakaolinite is associated with dehydration of clay and it increases the clay reactivity for easily alumina extraction by acids or alkalis [22,26].…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of silica nanoparticles from clay

Zulfiqar

Subhani

Husain

2016

Journal of Asian Ceramic Societies

101

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We report a method to synthesize silica nanoparticles from bentonite clay. A series of thermal and acid treatment processes was performed on bentonite clay to lower the alumina and increase the silica content. The obtained silica rich clay was treated in two different concentrations (10 wt% and 40 wt%) with sodium hydroxide solution to form sodium silicate solutions (SSS). One type of SSS was hydrolyzed with three different concentrations (5 M, 10 M and 15 M) of nitric acid in the presence of ethanol as cosolvent while the other SSS was hydrolyzed with nitric acid in the presence of three different quantities (10 ml, 20 ml and 30 ml) of ethanol as cosolvent. A range of silica particle sizes from nanometer to micrometer was obtained by varying the contents of silica rich clay, HNO 3 , and ethanol. It was observed that the concentration of silica rich clay and HNO 3 had a direct effect on the particle size. The increase in the quantity of ethanol from 10 ml to 20 ml produced bimodal particles of nanometer and micrometer size, which maintained at 30 ml. Inductively coupled plasma optical emission spectroscopy, atomic absorption spectroscopy, X-ray fluorescence, scanning electron microscopy and X-ray diffraction were utilized to characterize the clay, SSS and nanoparticles.

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“…Although the general heat-induced effects on the montmorillonite structure have been examined intensively, the effects of heat on moisture transport and, therefore, on the binding properties of bentonite-bonded moulding sands were subject to only very few studies (Holtzer et al, 2011;Bobrowski & Grabowska, 2012;Zymankowska-Kumon et al, 2012). Likewise, effects of cyclic reuse on the properties of moulding sand are far from being known satisfactorily.…”

Section: Introductionmentioning

confidence: 99%

Effects of heat and cyclic reuse on the properties of bentonite-bonded sand

Schiebel¹,

Jordan²,

Kaestner³

et al. 2018

ejm

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Bentonite-bonded quartz sand is the most common mould material used in foundry industry. During casting, however, the moulding sand undergoes alterations, which deteriorate its properties. Aim of this work, therefore, was to gain accurate insights into the relation between smectite alteration and property change. To this end, the wet tensile strengths of heat pre-treated and cyclically reused sands were related to the kinematics of water within the sand as measured by in-situ neutron radiography and neutron diffraction. Sands subjected to 22 cycles of drying (T = 120°C) and remoistening (3 wt%) revealed modifications of the d values of the basal reflections of smectites. No significant change of tensile strength, however, was associated with these modifications. Contrarily, sands pre-treated with temperatures as low as 225°C revealed a reduction of tensile strength, which was neither correlated to the loss of tightly bound water nor to dehydroxylation. For temperatures above 300°C a correlation between the reduction of tensile strength and the loss of tightly bound water or early dehydroxylation was evident. With completing dehydroxylation of the smectites above 670°C, total loss of wet tensile strength of the pre-heated sands was observed. The results showed that cyclic use of moulding sand had little impact on the sand quality as long as the temperature of the sand remained low. For the practice in foundry, the results imply that a rigorous separation of heat-exposed sand is advantageous.

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Influence of the Changes of the Structure of Foundry Bentonites on Their Binding Properties

Cited by 14 publications

References 14 publications

Bentonite-hydrochar composite for removal of ammonium from Koi fish tank

Bentonite-hydrochar composite for removal of ammonium from Koi fish tank

Synthesis and characterization of silica nanoparticles from clay

Effects of heat and cyclic reuse on the properties of bentonite-bonded sand

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