Mixture Of Kaolin Research Articles

Effects of Temperature and Duration of Anorthite Synthesis from Mixtures of Kaolin and Calcite

Effects of Temperature and Duration of Anorthite Synthesis from Mixtures of Kaolin and Calcite

Influence of the nature and amount of carbonate additions on the thermal behaviour of geopolymers: A model for prediction of shrinkage

In order to develop fire resistant geopolymer materials, it is necessary to understand the parameters controlling their thermal behavior such as the content of alkali or rare earth cations. This study highlights the effect of carbonate nature and amount on the thermal behavior of geopolymers in order to propose a model of thermal behaviour and predict shrinkage. For this, various mixtures of kaolin and calcite and/or dolomite with different percentages were calcined at 600 and 750 °C. The feasibility of consolidated materials based on these mixtures were evaluated and the thermal behavior of the obtained materials was investigated. The characterization of the mixtures revealed the persistence of carbonates after calcination at 600 °C and their partial decomposition after calcination at 750 °C. This fact was explained in the case of high dolomite content by the existence of kaolinite gangue hindering its decomposition. Consolidated materials were obtained from the different mixtures. After thermal treatment at 1000 °C, it was evidenced that the amorphous phase crystallizes to form in a major part leucite. At lower available alkaline earth species (Ca2+ and Mg2+) content, only wollastonite is formed and the shrinkage varies between 15 and 12%. However, at higher content, different calcium and magnesium silicates can be formed such calico-olivine and larnite in the case of calcite based materials and akermanite and merwinite for dolomite based materials. This fact leads to lower shrinkage value (from 6 to 8%). Thus, it is possible to control the thermal behavior and predict the shrinkage of geopolymer materials by controlling the available alkaline earth cations.

Artificial neural network prediction of CO emission and ash yield from co-combustion of empty fruit bunch, palm kernel shell and kaolin.

The quantity of ash yield and carbon monoxide (CO) emitted during co-combustion of empty fruit bunch (EFB), palm kernel shells (PKS) and kaolin in a grate furnace depend on the fuels mixing ratio, the combustion temperature and duration. These factors can be tuned to minimize ash deposition and CO emission which is partly responsible for the greenhouse effect. In this study, seventy-three (73) data points were obtained from combustion of EFB, PKS and kaolin mixtures based on D-optimal design. Artificial neural network (ANN) model, optimized with Taguchi technique, was developed to predict ash yield (AY) and CO emission from the combustion of the fuel mixture. The data were divided into training, validation and testing in a 2:1:1 relative proportion. The optimized ANN architecture for AY and CO emission were 5-11-3-1 and 5-6-3-1, respectively, with scale conjugate gradient training algorithm and a learning rate of 0.1. Results of the ANN model agreed significantly with the experimental results with coefficients of determination (R2) of 0.96 and 0.93 for ash yield and CO emission, respectively. The mathematical models for the ash and CO emission using the D-optimal design indicate a good fit with R2 of 0.916 and 0.906, respectively. Parametric studies based on the two models showed that ash yield and CO emission reduced with increased combustion temperature and increased fraction of PKS within the temperature range of 800-1000 °C. These results indicated that both ANN and D-optimal can be deployed to select mixture with minimal ash yield and CO emission.

The Optimisation Analysis of Sand-Clay Mixtures Stabilised with Xanthan Gum Biopolymers

Sand–clay mixtures can be encountered in both natural soils (e.g., residual soils, clay deposits and clinosols) and artificial fills. The method of utilising biopolymers in ground improvement for sand–clay mixtures has emerged recently. However, a full understanding of the strengthening effect of biopolymer-treated sand–clay mixtures has not yet been achieved due to a limited number of relevant studies. In this study, xanthan gum (XG), as one of the eco-friendly biopolymers, was used to treat reconstituted sand–clay mixtures that had various compositions in related to clay (or sand) content and clay type (kaolin and bentonite). A series of laboratory unconfined compression strength (UCS) tests were conducted to probe the performances of XG-treated sand–clay mixtures from two aspects, i.e., optimum treatment conditions (e.g., XG content and initial moisture content) to achieve the maximum strengthening effect and strengthening efficiency for the sand–clay mixtures with different compositions. The experimental results indicated that the optimum initial moisture content decreased as the sand content increased. The optimum XG content, which also decreased with the increasing sand content, remained approximately 3.75% for all sand–kaolin mixtures and 5.75% for all sand–bentonite mixtures if calculated based on clay fraction. While untreated sand–kaolin mixtures and sand–bentonite mixtures had comparable UCS values, XG-treated sand–kaolin mixtures seemed to have better improved mechanical strength due to higher ionic (or hydrogen) bonds with XG and low-swelling properties compared with bentonite. The deformation modulus of XG-treated sand–clay mixtures were positively related with UCS. The variation in UCS and stiffness for each treatment condition increased as the sand content was elevated for both sand-kaolin and sand-bentonite mixtures. An increment in the proportion of the heterogeneous composite formed by irregular sand particles conglomerated with the XG–clay matrix in total soil might be responsible for this phenomenon.

Fabrication of zirconia-kaolin dual layer hollow fiber membrane: Physical and performance study for industrial wastewater treatment

This work aims to prepare a robust yet low-cost dual-layer hollow fibre ceramic membrane composite membrane (DLZK) fabricated by co-extrusion phase inversion/co-sintering technique to be used in wastewater treatment. The dope suspensions were extruded simultaneously where the outer layer consists of zirconia while the inner layer consists of a mixture of kaolin and zirconia to enhance membrane performance in terms of mechanical strength and wastewater treatment capability. The effects of co-sintering temperature from 1200 to 1500 °C on the membrane’s mechanical strength, porosity, pore size, water permeability, and dissolubility in high alkaline/pH condition were investigated. The membrane performance was evaluated by real wastewater treatment test using two different types of industrial wastewaters which are palm oil mill effluent and textile industry wastewater. The findings show that the proposed method of producing the DLZK membranes could provide good interfacial adhesion and well-dispersed zirconia in the outer layer and the use of kaolin as an alternative natural material for ceramic membrane fabrication. The DLZK co-sintered at 1200 °C had the mechanical strength of 65 MPa, only 3.5 % loss of the original shape in high alkaline solution, and removed almost 95 % for all parameters of COD, TOC, TN, NH3-N and TSS in the both wastewaters suitable for microfiltration purpose.

Preparation of anorthite ceramics using SPS

A mixture of kaolin (92 wt.% of kaolinite) and laboratory-grade CaCO3 was used for anorthite preparation using the spark plasma sintering (SPS) technique. The powder was heated up to the maximum temperature (850 °C–1100 °C with a step of 50 °C, heating rate 50 °C/min) using the SPS device. The as-prepared samples were compared with a reference sample produced by dry pressing and conventional firing. Rietveld refinement performed on the X-ray diffraction data revealed that before anorthite formation, gehlenite and Ca-feldspar appeared, which gradually transformed into anorthite with increasing temperature. The sample prepared by SPS at 1100 °C contained 90 wt.% of anorthite, while the anorthite content in the reference sample reached only 47 wt.%. The porosity of the samples prepared by SPS reached significantly lower values compared to that of the reference sample. Therefore, SPS can be considered as a promising technique in the preparation of anorthite ceramics at lower temperatures.

Analysis the effect of TiO2 addition on sintering, physical mechanical behavior of porcelain insulating material

The present study is aimed to develop a high strength porcelain insulating material from locally available low cost raw porcelain materials by reinforcement of TiO2 (0 to 10 in wt.%) as a substitute replacing ZrO2 in the base porcelain material composition. Base porcelain composition was prepared from the mixture of kaolin, ball clay, quartz, feldspar. Pellets were prepared by applying a constant pressure of 170 MPa using isostatic hydraulic press with holding for a period of 10 min. Different characterizations techniques such as; X-ray diffraction (XRD) and scanning electron microscopy (SEM) used to evaluate the structural and micro structural changes, respectively by increasing the concentration of TiO2 (0–10 wt.%) and decreasing ZrO2 (10–0 wt.%) concentration at the base composition of porcelain composition. The measurement of mechanical strength and physical behavior of TiO2 and ZrO2 were analyzed for all the samples prepared with different compositions at sintering temperature (1250 and 1350 °C) with soaking period of 2 h. The base porcelain composition with 5 wt.% TiO2-doped concentration yields the better physical and mechanical strength. The investigated TiO2 based porcelain material using in refractory and high-temperature insulating applications where severe thermal shock with high mechanical features are required.

Design and fabrication of cylindrical ceramic crucible as insulator for energy storage systems

The ubiquitous demand for thermal energy in domestic and industrial applications, necessitates the need that heating systems, are effectively insulated, portable and occupy less space. This research focuses on the design and fabrication of a portable crucible for insulating a thermal energy storage system operating at high temperature. The insulating properties of the crucible were also investigated. Two ceramic crucibles, comprising of kaolin, and a mixture of kaolin and sand, were fabricated using the parameters obtained from simulation. When subjected to thermal treatment, the crucible comprising of kaolin and sand structurally failed at 75 °C. However, the crucible comprising of only kaolin remained stable and attained steady state at a temperature of 200 °C. The heating and cooling temperature curves of the kaolin crucibles were plotted and the estimated thermal conductivity of the kaolin crucible was 0.09 W/mK at 200 °C; this is in good agreement with theoretical values of kaolin which range from 0.03 to 0.3 W/mK. The computed thermal diffusivity is 4.9x10-8 m2/s, which is much lower when compared with the thermal diffusivity of insulating materials like polystyrene, glass fibre and rock wool. Thus, the rate at which heat diffuses through the crucible is low, making it suitable for insulating a thermal energy storage material operating at 800 °C. The results of this study will facilitate an efficient way of transporting stored thermal energy in portable insulating containers.

Sequestration of Carbon Dioxide Using Ground Granulated Blast Furnaces Slag and kaolin mixtures

<p>Mineral carbonation has been utilised extensively worldwide as the most important way of permanently sequestering carbon dioxide (CO2). This study objective includes sequestering of CO2 gas from atmosphere via carbonation of magnesium and calcium. Waste materials such as ground granulated blast furnaces slag (GGBS) extracted through iron manufacturing as well as brown kaolin mixtures were employed. Acid digestion method as well as thermogravimetric analysis were employed to quantify CO2 sequestered by GGBS-kaolin mixtures.The outcomes indicated that the acid digestion technique is more dependable compared to TGA in measuring CO2. Nonetheless, both methods deduced that the quantity of CO2 sequestered is about 5% from the total dry mass of the mixtures. Thus, GGBS-kaolin mixtures effectively sequester a substantial quantity of CO2.</p>

Analysis of Fouling Characteristics of Diatomite Ceramic Membrane Using Filtration Models

Ceramic membrane has made rapid progress in industrial/municipal wastewater treatment and drinking water treatment owing to its advantageous properties over conventional polymeric membrane. The ceramic membrane processes are a rapidly emerging technology for water treatment, yet virtually no information on the performance and fouling mechanisms diatomite ceramic membrane. In this study, filtration experiments were carried out using a mixture of humic acid and kaolin which simulated surface water under constant pressure to reveal fouling characteristics of the filtration of the diatomite ceramic membrane. The results showed that the removal rate of VU254 was 52%~70%, and turbidity was 90%~95% when treat mixed water of 5-10mg/L kaolin and humic acid. And membrane surface retention and membrane pore adsorption were the mainly removal routes. And the flux slowly decreases, rapidly decreases, gradually decreases and stabilizes were three processes of diatomite ceramic membrane fouling. And the first and third stages of membrane fouling mainly caused by complete blocking, and the second stage was mainly controlled by standard blocking. The study found that humic acid would cause both the pore blocking and the fouling of the membrane surface when turbidity was present, especially the membrane surface pollution, it was the major factor of diatomite ceramic membrane fouling.

Effect of TiO2 on mullite formation in mixture of Nigeria sourced kaolinite and calcined alumina

In this study, the effect of TiO2 when added to a mixture of Nigerian sourced of kaolin and calcined alumina powder (50:50) was investigated. The influence of Ti4+ ion on the physico-mechanical property (apparent porosity, bulk density and modulus of rupture), phase and microstructural evolution was studied at sintering temperature of 1600?C when mullitisation has been maximized based on previous reports. The sintered samples showed considerably high porosity of about 16 %, a slight reduction of about 5 % in porosity was observed on TiO2 addition. There was no appreciable change in the bulk density due to TiO2 doping, but the modulus of rupture (MOR) reduced appreciably from 43 MPa to 36 MPa on TiO2 doping. As shown by the XRD, mullite was seen as the major phase with negligible cristobalite phase for the undoped sample. The TiO2 doped sample displayed mullite as major and corundum as minor phases. There appeared more mullite phases in the doped sample than the undoped sample indicating a higher percentage of mullite formation. The microstructural study shows the presence of acicular mullite with round edges and good aspect ratio. The presence of inter-granular and intra-granular pores in TiO2 doped samples might have contributed to the reduction in strength observed at 1600?C.

Recycling glass wool as a fluxing agent in the production of clay- and waste-based ceramics

Abstract Concerns about the management of glass wool waste, approximately 800,000 tons of which are generated annually in Europe, are increasing. To test the feasibility of incorporating this waste into ceramic materials, this study examined the reuse of glass wool as a fluxing agent in the production of clay- and waste-based building ceramics. Commercial kaolin clay and two industrial residues, namely quartz-feldspar sand (QFS) and copper slag (CS), were selected as the precursors. Six compositions were prepared, three samples containing glass wool and three counterparts without glass wool, and then sintered at 750, 850, and 950 °C. The materials and prepared ceramics were characterized by employing x-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive x-ray spectroscopy (EDS), differential scanning calorimetry (DSC), water absorption, apparent density, and compressive and flexural strength tests. Interestingly, the results indicated that incorporating 10 wt% of glass wool into the QFS, CS, and kaolin mixtures created ceramics with better physical, mechanical, and microstructural properties. This was ascribed to the glass wool melting reactions observed from approximately 700 °C. The QFS samples with glass wool and sintered at 950 °C achieved compressive strength values as high as 117 MPa and water absorption percentages as low as 2%. However, the fluxing effect of glass wool was less significant in the CS- and kaolin-based ceramics, likely due to differences in their chemical composition, mineralogy, and particle-size distribution. The results of this study emphasize the reuse potential of glass wool and other waste streams in building ceramics and could contribute to improving the management of glass wool waste in line with social sustainability objectives.

Kaolinite-Magnesite or Kaolinite–Talc-Based Ceramics. Part II: Microstructure and the Final Properties Related Sintered Tapes

In recent decades, talc and kaolinite have been widely used as raw materials for the ceramic industry. In this study, the final characteristics of kaolinitic clay mixed with 6 mass% of magnesite obtained in our previous work were compared with those obtained with mixtures of kaolin (kaolin BIP) and talc (as the source of magnesium oxide). However, different amounts of talc in the kaolin powder were studied, namely 10, 30, and 50 mass% of added talc (with respect to kaolin + talc). The tape casting process was used during this work in order to manufacture the green tapes in an aqueous system with 0.2 mass% of dispersant. Subsequently, the green tapes were heated to 1000 and 1100 °C with a dwelling time of 12 min. The green and sintering tapes were characterized using the following techniques: DTA/TG, X-ray diffraction, porosity, and flexural strength analyses. The results obtained from our previous work indicate that the specimen with 6 mass% of MgCO3 sintered at 1200 °C for 3 h exhibited the best performances, with high flexural strength and weak porosity value—117 MPa and 27%—respectively. As results from this study, the optimal mechanical and thermal properties of sintering tapes were obtained for the specimen with 10 mass% of added talc sintered at 1100 °C. Indeed, this specimen exhibited 50 MPa and 43% of stress to rupture and apparent porosity, respectively.

The use of technogenic raw materials to produce a high-alumina chamotte

When fused corundum is crushed, a finely dispersed powder is formed with an Al2O3 content of 93–95%, in the form of substandard material. It is advantageous to utilize this powder to obtain high-alumina chamotte with Al2O3 content of more than 62%. High-alumina aggregate (chamotte) was obtained by semi-dry technology with intermediate briquette molding from a mixture of corundum dispersed powder and enriched kaolin. Based on a final Al2O3 content of 65 wt. % the batch composition of the mass to produce a high alumina aggregate (chamotte) was calculated. From a mixture of dispersed corundum powder and kaolin moistened with a 5–7% technical lignosulfonate solution with a density of 1050 kg·m−3, a briquette was formed at a specific pressing pressure of 15–20 MPa. The briquette was fired at a temperature of 1700°C. The fired briquette had a strength of 164 to 193 MPa. The water absorption of briquettes was 11–12%. The phase composition of the briquette is represented mainly by corundum and mullite. The enriched kaolin did not show sintering effect on fine corundum.

Technogenic Raw Materials in High-Alumina Chamotte Production

The paper presents studies on the production of a high-alumina aggregate with an Al2O3 content of 75% based on fine-grained corundum dust generated by grinding fused corundum. Finely dispersed corundum powder is a by-product and due to the low Al2O3 content (93 – 95%) is not used in further production. It is proposed to obtain high-alumina aggregate without joint grinding of the components. Aggregate was obtained by pressing through a “false grain” from a mixture of kaolin and corundum dust in a certain ratio. The samples firing was carried out at a temperature of 1700°C. The phase composition of the obtained aggregate is represented by 46 – 51% corundum, 45 – 49% mullite. The water absorption of such chamotte is 14 – 16%, open porosity is 33 – 35%, apparent density is 2230 – 2290 kg·m−3. Now, it was not possible to obtain a high-density filler grade ZML and ZMK that meets the requirements of GOST 23037 – 78. The production flow chart of high-alumina chamotte based on kaolin and corundum dust should include a joint fine grinding of the components, or a separate grinding of corundum dust until it passes completely through the 0.063 mm mesh.

Effect of kaolin and argillite mixtures on the dielectric properties of geopolymers

The use of geopolymer in radiofrequency applications and more precisely in antenna is innovative. The objective of this study is to highlight the impact of mixtures of kaolin and argillite on the structure and dielectric properties of geopolymers for antenna application. For this, six geopolymer formulations based on mixtures of kaolin and argillite with different proportions (33, 50 and 67%) and calcined at 600 and 750 ​°C were studied using mercury intrusion porosimetry, dielectric measurements and NMR spectroscopy. Low porosity values were obtained whatever the mixture. At 600 ​°C, the porosity increases with the increase of argillite content from 18 to 23%. At 750 ​°C, no impact of argillite content on the porosity (16%) was detected. However, the pore size increases with increasing the argillite content regardless of the calcination temperatures due to the unreacted secondary phases present in argillite. MAS-NMR experiments on geopolymer samples and calcined mixtures have evidenced a strong correlation between reactive aluminum resulting from dehydroxylation of kaolin and clay minerals of argillite and the geopolymerization rate. These structural variations influence the dielectric properties. Indeed, ε and tan ​δ values increase with the increase of argillite content and calcination temperature due to the increase in the number of moles of free alkali earth cations (Ca2+ and Mg2+).

The Effect of Sodium Hydroxide (NaOH) Solution Concentration on Properties of Geopolymer Paste

This research analyzes the effect of sodium hydroxide (NaOH) solution concentration ranging from 8M to 12M as alkaline activator on the properties of geopolymer paste. Alkaline activator is essentially a mixture of sodium hydroxide and sodium silicate solution. In this research, the main component used was raw kaolin. In order to produce kaolin based geopolymer paste, the alkaline activator solution was prepared with 0.24:1.00 ratio of Na2SiO3/NaOH and this alkaline activator solution was prepared for 24 hours prior before used in another process. The solid-to-liquid ratio which is kaolin-to alkaline activator solution ratio was 0.80:1.00. The mixture of kaolin based geopolymer paste were placed in cube moulds with a size of 50x50x50 mm, and left for 24 hours until it hardened. Then, the samples were cured at 80? in the oven for 24 hours. The samples of kaolin based geopolymer paste were tested based on compressive strength, morphology analysis, water absorption and porosity after 28 days. In this project, 8M concentration of NaOH solution was the best concentration in order to study the synthesis of kaolin based geopolymer paste as the sample had the highest amount of compressive strength with 0.992 MPa and had the lowest water absorption and porosity with 1.246% and 24.08% respectively. Scanning Electron Microscope (SEM) was used to observe the morphological structure of the kaolin based geopolymer paste. The sample with 8M concentration of NaOH solution shows that least amount of unreacted particles. The structure of kaolin based geopolymer paste was more dense at 8M concentration as the size of pore decreases. The kaolin based geopolymer paste is suitable for use in the construction building industry as a finishing product such as coating.

One pot fusion route for the synthesis of zeolite 4A using kaolin

A new process route for obtaining zeolite 4A from kaolin was realized by subjecting all raw materials needed for hydrothermal synthesis to thermal activation in one pot method. For that purpose, different routes of activation steps for kaolin, which are metakaolinization, alkali fusion and one pot fusion were investigated for a wide range of kaolin sources in order to obtain zeolite 4A product with highest crystallinity. The influence of Si/Al ratio in addition to the chemical composition of raw kaolin, i.e. quartz and iron impurity content, on the product 4A was investigated following all three activation routes. It was found that alkali fusion process allows incorporation of quartz as silicon source during the hydrothermal synthesis of zeolite 4A, which may result in a variety of products such as zeolite P and zeolite 13X. In this study, a novel approach was developed by thermal activation of a mixture of kaolin, alkali and alumina sources at once in one pot route, which was followed by hydrothermal synthesis. The current study indicates the possibility of adjusting Si/Al ratio adding Al(OH)3 during the activation step in one pot fusion process, which resulted in synthetic zeolite 4A of higher than 90% crystallinity using low quality kaolin.

Study on the thermal stability of stabilized and unstabilized low-density polyethylene films

The oxidation and thermal stability of low-density polyethylene (LDPE) films (stabilized and unstabilized) used as greenhouse covering have been investigated. A mixture of kaolin, UV absorber, hindered amine light stabilizers (HALS) and heavy metals was used to stabilize LDPE films; these films were also compared with unstabilized LDPE films. Both films were exposed to natural weathering in Laghouat, Algeria. The oxidation resistance of unstabilized specimens for different ageing periods was determined by measuring the oxidation induction time (OIT) at 180 °C. It has been found that the highest OIT value was obtained for the unaged film and the values decline with ageing time. On the other hand, the stabilized specimens showed a significant stability under the conditions of OIT determination experiments. Furthermore, the oxidation resistance of these samples was evaluated by measuring the oxidation onset temperature (OOT). The results obtained showed that the OOT of the stabilized films ranges from 219 to 236 °C. Finally, a comparative analysis of the thermal stability results of both films was conducted. The activation energy of the photodegradation process of the both films was calculated by using TGA thermograms following the isoconversional approach. The results revealed that the stability of the stabilized specimens diminishes with ageing time and that the stabilizer additives improve the thermal stability of LDPE films. The influence of the photooxidation on the degree of crystallinity (based on DSC and WAXS techniques) of both films was also reported. Generally, there is a strong correlation between TGA, OIT, OOT, UV and FTIR results.

Maximum dry density of sand–kaolin mixtures predicted by using fine content and specific gravity

Numerous studies have covered the comparison of maximum dry density (MDD) toward the combination of soil properties and compaction parameters. These combinations are dominated by Atterberg limits, moisture content, and compaction effort. Nevertheless, minimal efforts have been expended in predicting the MDD using two simple soil properties, i.e., fine content (FC) and specific gravity (Gs). Sand–kaolin mixtures were compacted and then used to examine the correlation between MDD, FC, and Gs through different moisture content, and FC ranged from 20 to 70%. The results showed the importance of considering both Gs and FC in the correlation estimation in order to reduce the uncertainty of using only FC as a single parameter. A linear relationship was obtained with an excellent correlation coefficient (R2 = 0.99) between MDD and the ratio of FC/Gs2. The empirical correlation equation was justified using data from 163 measured MDD obtained from previous studies. All predicted MDD were within the confidence interval of ± 10, which confirmed a low error range of the predicted MDD. The application of the equation was limited to FC and FC/Gs less than 77% and 0.302, respectively. It should, however, be noted that the presence of a high amount of gravel in the soil mixture will not be applicable for this correlation.