Source Of Calcium Carbonate Research Articles

Selective Leaching of Lithium and Beyond: Sustainable Eggshell-Mediated Recovery from Spent Li-Ion Batteries

This study introduces an innovative strategy for the selective leaching of lithium from spent Li-ion batteries. Based on thermodynamic assessments and exploiting waste eggshells as a source of calcium carbonate, an impressive 38% of lithium was dissolved selectively through mechanical milling and water leaching, outperforming conventional thermochemical methods. Afterwards, a hydrogen peroxide-assisted sulfuric acid leaching was also implemented to solubilize targeted elements (Mn, Co, Ni, and Li), with an exceptional 99% efficiency in Mn removal from the leachate using potassium permanganate and a pH range of 1.5 to 3.5. Selective separations of Co and Ni were then facilitated utilizing CYANEX 272 and n-heptane. This comprehensive study presents a promising and sustainable avenue for the effective recovery of Li and associated co-elements from spent lithium batteries.

Preparation and Characterization of Hydroxyapatite Using Precursor Extracted from Cockle Shell Waste

Hydroxyapatite (HAP) is a widely used biomaterial due to its excellent bioactivity, biocompatibility, and structural similarity to the mineral component of human bone and teeth. However, the synthesis of HAP typically relies on expensive and non-renewable precursors, which can limit its widespread applications. This study investigates the extraction and purification of HAP from cockle shells, which are a readily available and renewable source of calcium carbonate. The extraction and purification of hydroxyapatite (HAP) from cockle shells, which are rich in calcium carbonate, is a promising method for producing HAP for biomedical applications due to its bioactivity and biocompatibility. This study investigates the use of a calcination process and wet slurry precipitation technique to produce HAP from seashells, focusing on the effect of reaction time of phosphate source (KH2PO4) and calcium oxide (CaO) on HAP production. EDX reported Ca/P ratio of 1.61 for HAP synthesized by chemical precipitation for 2 hours of reaction. Meanwhile, the XRD results indicate that a 4-hour reaction time produces more crystalline HAP than shorter reaction times, highlighting the importance of reaction time in HAP synthesis. This research demonstrates the potential of utilizing seashell waste as a valuable natural resource for applications in healthcare and waste management.

Development of phase change eco-composite materials from eggshell waste

ABSTRACT The consumption of eggshell powder (ES) as an affluent source of calcium carbonate (CaCO3) can efficiently solve both ecological and financial interest. The use of eggshell waste in eco-composite materials (ECPCMs) is an attempt to reduce waste's negative effects. Eco-composite powders of polyethylene glycol (PEG) and calcium carbonate (CaCO3) were obtained by mechanical grinding. Compression molding was used to produce plates from the ground powders. FTIR spectroscopy and X-ray diffraction analysis showed that the ECPCMs were physically combined and the crystallinity of the two components was affected. According to TGA, the thermal stability of ECPCMs was improved, thanks to the use of eggshell waste powder. On the other hand, the results of the DSC showed that ECPCM with the addition of 90 wt% of PEG in the mixture provides excellent thermal stability and high energy storage density. In light of its high latent heat storage capacity of 156.1 J/g as well as its ability to prevent PEG exudation. Significant enhancement in melting-solidification time shows an improvement in Thermal Energy Storage (TES) response time by adding ES to the PCM. The obtained results indicate a good potential for industrially applied ECPCMs.

Use of shells for the mechanical stabilisation of sediments: a valuable geomechanical perspective?

The present study contributes to developing a novel eco-friendly solution for the mechanical stabilisation of dredged marine sediments by using mussel shells – another high-impact waste of marine origin – in the partial replacement of cements. What are the underlying chemo-mechanical interactions affecting the evolution of such mixtures? Can mussel shells replace cement without compromising useful geomechanical and geochemical properties of the stabilised sediments? Can such mixtures still be modelled as soils when it comes to their geotechnical design and analysis? The paper answers these questions by assessing the mechanical performance of mixtures formed by sediments stabilised with three types of cement and a mussel shell powder and comparing them with those of the same sediments treated with cement only. Multiple beneficial effects of the use of mussel shell powder, as a peculiar source of calcium carbonate from its biogenic origin, have been demonstrated: it acts as a void filler; enhances the electrolytic exchanges between sediment and cement, and increases the contact area between the mineral particles promoting the chemical hydration reactions. As a result, for fixed replacement ratios, the original mixtures still exhibit soil-like behaviour consistent with traditional geomechanics and even better performance than the control mixtures.

263 Effects of source of calcium carbonate and microbial phytase on standardized total tract digestibility of calcium by growing pigs

Abstract The objective of this experiment was to test the hypothesis that there are differences in the standardized total tract digestibility (STTD) of Ca and in response to microbial phytase among sources of calcium carbonate obtained from different regions of the world. Barrows [n = 320; average body weight (BW) = 17.47 kg; SD = 1.28] were allotted to 40 diets using a completely randomized block design with eight blocks of 40 pigs for a total of eight replicate pigs per diet. All diets were based on corn and potato protein concentrate. Twenty sources of calcium carbonate were obtained from different regions of the world, including the United States, Europe, Asia, and South Africa. Each source of calcium carbonate was used in two diets, one diet without microbial phytase and one diet that contained 1,000 phytase units/kg diet. Pigs were housed individually in metabolism crates. Pigs were provided feed at 3.0 times the maintenance requirement for energy. Feces were collected for 4 d following the adaptation period after 5 d of adaptation. Fecal samples were dried, ground, and analyzed for Ca to calculate the digestibility. The initial statistical model included calcium carbonate source, phytase, and the Ca-source × phytase interaction as fixed effects; however, no interactions between Ca source and phytase were observed. Therefore, the final statistical model included only Ca source and phytase as fixed effects. A second analysis was performed to compare the digestibility of Ca in calcium carbonate obtained from different regions of the world (i.e., Europe, Asia, the United States, and South Africa). In this model region, phytase, and the region × phytase interaction were fixed effects. However, no interactions between region and phytase were observed and therefore, the final statistical model included only region and phytase as fixed effects. Concentrations of Ca in the 20 sources of calcium carbonate ranged from 32.1 to 40.9% (Table 1). Differences in the STTD of Ca were observed among pigs fed diets containing different sources of calcium carbonate (P < 0.001). Pigs fed diets containing 1,000 units of phytase had greater (P < 0.001) STTD of Ca compared with pigs fed diets containing no phytase. The STTD of Ca in calcium carbonate from the United States was less (P < 0.001) than in calcium carbonate from Europe, Asia, or South Africa. In conclusion, the use of microbial phytase increases the STTD of Ca in calcium carbonate, but the STTD of Ca varies among different sources and among sources from different regions. Therefore, consideration should be given to differences in analyzed concentrations of Ca, values for STTD of Ca, and response to microbial phytase among different sources of Ca carbonate to ensure Ca is not being oversupplied when formulating diets.

The Compressive Strength of Unsaturated polyester reinforced by natural and synthetic Calcium Carbonate

A modifications on the ultimate compression strength of unsaturated polyester (UPE) carrying out, by adding nano Chicken eggshells fibers (E.S) as a natural source of calcium carbonate or synthetic nano calcium carbonate particles (CaCO3) in different weight percentages ranging from (1-5%). The ratio (1% eggshell fibers) and (3% CaCO3) are the best weight ratios that selected according to ultimate compressive strength of Unsaturated Polyester composites. Ultamite compressive strength was improved from (73.84 N/mm2) for UPE to (85.54 N/mm2) for (UPE/1% E.S) composite and to higher value (87.88 N/mm2) for (UPE/3%CaCO3) composite. The partictes with nano-sized of titanium dioxide (TiO2) was used to reinforce the two best composites, to get more improvement in there ultamite compressive strength to reach to (94.27 N/mm2) for (UPE/1%E.S) and to (100.18 N/mm2) for (UPE/3%CaCO3) composites.

Utilization of carbonated alkaline solid wastes in ordinary Portland cement-metakaolin-limestone ternary mixture: Underlying the role of low grade-sustainable calcium carbonate sources

Alkaline solid wastes are widely generated as by-products annually from construction demolition, steel making, and metal refining industries. Consequently, there is high pressure on their disposal and environmental protection. Carbonation treatment of alkaline solid wastes provides a potential way to valorize CO2 and produce low-grade artificial limestone particles. This study investigates the utilization of carbonated alkaline wastes, including recycled cement fines, steel slag, iron recycled steel slag, and magnesium slag in green ternary cement (limestone-metakaolin-cement system) production. The detailed characterization of carbonated alkaline solid wastes and the performance of metakaolin-cement based ternary systems were evaluated. The reaction mechanism of carbonated alkaline wastes in metakaokin-cement based binder is proposed. The results indicated carbonated alkaline solid waste powder containing relatively low calcite (14.4%–50.38%) and negative surface charges. In addition, the amount of reactive Si at Q3 and Q4 were observed. The precipitated calcite on the surface of particles resulted in the deterioration of the workability of ternary mixtures compared to natural limestone. However, the equivalent amount of CO3-AFm phases produced by precipitated calcium carbonate and additional hydrates from the reaction of amorphous silica in carbonated alkaline solid wastes contributed to a comparable mechanical performance (49.5 MPa–50.82 MPa) and compact microstructure of ternary binders. Carbonated alkaline solid wastes can be a sustainable component to replace natural limestone in green ternary cement production.

Sustainable and Environmentally Friendly Microwave Synthesis of Nano-Hydroxyapatite from Decarbonized Eggshells.

The sustainable microwave (MW) synthesis of hydroxyapatite (HAp) from decarbonized eggshells was investigated. Decarbonization of eggshells, as a natural source of calcium carbonate (CaCO3), was carried out in the current study at ambient conditions to reduce the footprint of CO2 emissions on our environment where either calcination or acidic direct treatments of eggshells produce CO2 emissions, which is a major cause for global warming. Eggshell decarbonization was carried out via the chemical reaction with sodium hydroxide (NaOH) alkaline solution in order to convert eggshell waste into calcium hydroxide (Ca(OH)2) and simultaneously store CO2 as a sodium carbonate (Na2CO3) by-product which is an essential material in many industrial sectors. The produced Ca(OH)2 was mixed with ammonium dihydrogen phosphate (NH4H2PO4) reagent at pH~11 before being subjected to MW irradiation at 2.45 GHz frequency for 5 min using 800 Watts to prepare HAp. The prepared Nano-HAp was characterized using X-ray diffraction (XRD) where the crystal size was ~28 nm using the Scherrer equation. The elongated rod-like nano-HAp crystals were characterized using scanning electron microscopy (SEM) equipped with dispersive energy X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). MW synthesis of decarbonized eggshells is considered as a sustainable and environmentally friendly route to produce promising bioceramics such as nano-HAp. Concurrently, decarbonization of eggshells offers the ability to store CO2 as a high value-added Na2CO3 material.

An investigation of the source of calcium carbonate from the carbonated Portland cement: Based on the transformation of hydrates

In this work, two PC pastes were used to carry out accelerated carbonation experiments, and phase assemblages of paste samples collected at different sampling depths were analyzed. The source of CaCO3 originating from the carbonation reaction of hydrates in cement was quantitatively determined by a novel method based on the transformation of hydrates. Experimental results indicated that the phase assemblages in the carbonated zone of two PC pastes showed minor differences. C(A)SH, ettringite, AFm-CO3, and unhydrated cement particles in the complete carbonation zone of two cement pastes were carbonated and transformed into other phases. For the surface of two PC pastes (0–3 mm), calculations showed that the CaCO3 originating from the carbonation of calcium hydroxide and C(A)SH accounted for 75.3% and 72.6% of the total CaCO3, respectively. A concentration of 20% CO2 was not beneficial for the diffusion of CO2 and the subsequent precipitation of CaCO3 at the later period of carbonation.

Reservoir Characterization of Alluvial Glutenite in the Guantao Formation, Bohai Bay Basin, East China

Alluvial glutenite reservoirs have obviously stronger heterogeneous and more complex control factors than sandstone reservoirs. Taking the Binxian Uplift area in the Boahi Bay Basin as an example, the aim of this study is to clarify the characteristics and control factors of the alluvial glutenite reservoir quality and the influence of reservoir properties on hydrocarbon accumulation. Pore types in the study area mainly include residual intergranular pores, intergranular dissolved pores, intragranular dissolved pores, and mold pores. The residual intergranular pores and intergranular dissolved pores are the main pore types. Most samples have porosity greater than 15% and permeability is mainly concentrated between 50 mD and 500 mD. It is shown that lithology type, microfacies, and diagenesis have significant impact on the reservoir quality. The reservoir qualities of very fine sandstone and fine sandstone are better than those of conglomerate and gravel-bearing sandstone. Instead of grain size, sorting affects the alluvial glutenite reservoir quality significantly. Oil-bearing samples commonly have sorting coefficient less than 2 while non-oil-bearing samples have sorting coefficient larger than 2. There are significant differences in reservoir physical properties of different sedimentary microfacies. The stream flow in mid-alluvial fan (SFMA) and braided channels outside alluvial fans (BCOA) have relatively weaker compaction and better reservoir quality than the overflow sand body (OFSB) and debris-flow in proximal alluvial fan (DFPA). Calcite cementation, the main cement in the study area, commonly developed at the base of SFMA and BCOA and near the sandstone-mudrock contacts. The source of calcium carbonate for calcite cement mainly came from around mudstone. High calcite cement content commonly results in low porosity and permeability. Individual glutenite thickness is also an important influencing factor on reservoir quality. Reservoirs with large thickness (>4 m) have high porosity and permeability. Dissolution occurred in the reservoir, forming secondary dissolution pores and improving reservoir quality. The dissolution fluid for formation of secondary pores is mainly meteoric waters instead of organic acid. The reservoir property has an important influence on hydrocarbon accumulation. The lower limit of physical properties of an effective reservoir is a porosity of 27% and permeability of 225 mD. The findings of this study can be utilized to predict the reservoir quality of alluvial glutenite reservoirs effectively in the Bohai Bay Basin and other similar basins.

Stearate-Coated Biogenic Calcium Carbonate from Waste Seashells: A Sustainable Plastic Filler.

Waste seashells from aquaculture are a massive source of biogenic calcium carbonate (bCC) that can be a potential substitute for ground calcium carbonate and precipitated calcium carbonate. These last materials find several applications in industry after a surface coating with hydrophobic molecules, with stearate as the most used. Here, we investigate for the first time the capability of aqueous stearate dispersions to coat bCC powders from seashells of market-relevant mollusc aquaculture species, namely the oyster Crassostrea gigas, the scallop Pecten jacobaeus, and the clam Chamelea gallina. The chemical-physical features of bCC were extensively characterized by different analytical techniques. The results of stearate adsorption experiments showed that the oyster shell powder, which is the bCC with a higher content of the organic matrix, showed the highest adsorption capability (about 23 wt % compared to 10 wt % of geogenic calcite). These results agree with the mechanism proposed in the literature in which stearate adsorption mainly involves the formation of calcium stearate micelles in the dispersion before the physical adsorption. The coated bCC from oyster shells was also tested as fillers in an ethylene vinyl acetate compound used for the preparation of shoe soles. The obtained compound showed better mechanical performance than the one prepared using ground calcium. In conclusion, we can state that bCC can replace ground and precipitated calcium carbonate and has a higher stearate adsorbing capability. Moreover, they represent an environmentally friendly and sustainable source of calcium carbonate that organisms produce by high biological control over composition, polymorphism, and crystal texture. These features can be exploited for applications in fields where calcium carbonate with selected features is required.

Biomimetic Use of Food-Waste Sources of Calcium Carbonate and Phosphate for Sustainable Materials-A Review.

Natural and renewable sources of calcium carbonate (CaCO3), also referred to as "biogenic" sources, are being increasingly investigated, as they are generated from a number of waste sources, in particular those from the food industry. The first and obvious application of biogenic calcium carbonate is in the production of cement, where CaCO3 represents the raw material for clinker. Overtime, other more added-value applications have been developed in the filling and modification of the properties of polymer composites, or in the development of biomaterials, where it is possible to transform calcium carbonate into calcium phosphate for the substitution of natural hydroxyapatite. In the majority of cases, the biological structure that is used for obtaining calcium carbonate is reduced to a powder, in which instance the granulometry distribution and the shape of the fragments represent a factor capable of influencing the effect of addition. As a result of this consideration, a number of studies also reflect on the specific characteristics of the different sources of the calcium carbonate obtained, while also referring to the species-dependent biological self-assembly process, which can be defined as a more "biomimetic" approach. In particular, a number of case studies are investigated in more depth, more specifically those involving snail shells, clam shells, mussel shells, oyster shells, eggshells, and cuttlefish bones.

One-Part Alkali-Activated Materials Derived from Natural and Designed Blends of Clay and Calcium Carbonate Sources

One-Part Alkali-Activated Materials Derived from Natural and Designed Blends of Clay and Calcium Carbonate Sources

CO2 Capture and Direct Air CO2 Capture Followed by Integrated Conversion to Methane Assisted by Metal Hydroxides and a Ru/Al2O3 Catalyst

AbstractRising CO2 levels are leading to an increase in atmospheric greenhouse gas effect. Hydroxide salts have previously been shown to be promising reagents for capturing CO2. Utilizing a 5 %Ru/Al2O3 catalyst, the carbonates obtained through CO2 capture can then be hydrogenated to methane. This conversion occurs at relatively mild temperatures from 200 °C to 250 °C under 40 to 70 bar H2 with yields of up to 100 %. Natural sources of calcium carbonate, like eggshells and seashells, can also be partially converted to methane. The direct air CO2 capture and conversion of CO2 to methane was achieved as well in quantitative yields.

Conductive and self-cleaning composite membranes from corn husk nanofiber embedded with inorganic fillers (TiO2, CaO, and eggshell) by sol–gel and casting processes for smart membrane applications

Abstract The utilization of corn husk as a renewable bio-cellulose material for producing bio-composite membranes through wet chemical and sol–gel process offers numerous advantages. It is an abundant, inexpensive, nontoxic, and readily available agricultural waste product. To enhance the properties of bio-composite membranes, various particulate ionic fillers such as titanium dioxide, calcium oxide, and eggshell (as a source of calcium carbonate) are incorporated in different weight percentages (0, 1, and 5%). These fillers act as additives to the corn husk nanofiber mixed with polyvinyl alcohol during the formation of the biomembrane. The resulting biocomposite membranes exhibit several desirable characteristics. They are lightweight, easy to shape, biodegradable, nontoxic, and possess excellent physical, mechanical, thermal, and electrical properties. Moreover, the addition of 5 wt% of eggshell powder leads to an increase in the dielectric constant and electrical conductivity, reaching approximately 3.300 ± 0.508 and 1.986 × 103 (Ω·m)−1, respectively. These measurements were taken at a frequency of 500 Hz and a temperature of 27°C. Furthermore, these membranes demonstrate self-cleaning abilities due to a contact angle greater than 90°. The electrical properties of the biocomposite membrane improve with a higher percentage of inorganic filler, making them suitable for applications in smart membranes, as well as mechanical, electrical, and thermal systems.

CALCIUM CARBONATE ISOLATION FROM EGGSHELL TO MEET PHARMACOPOEIAL STANDARDS AND ITS EFFECTIVENESS AS AN ANTACIDS

Objective: Calcium carbonate is widely used in the pharmaceutical field as excipients and therapeutic agents. Calcium carbonate can be obtained from limestone, chalk, marble and dolomite. Other alternative is from eggshell. Calcium carbonate source from eggshell has several advantages including higher calcium carbonate content, fewer contaminants metal limit, and more brittle. Therefore, in this study, calcium carbonate had been isolated from eggshells which was expected to meet the requirements of Indonesian Pharmacopoeia (sixth edition) and having activity as antacid. Methods: Calcium carbonate were isolated from eggshells by mechanically and physically organic separation. The quality of calcium carbonate was examined according to the Indonesian Pharmacopoeia parameters including loss on drying; acid-insoluble substance, magnesium and alkali salt; limit of arsenic, lead, iron, mercury, heavy metal, and barium. Additional physicochemical characterization of calcium carbonate including particle size analyzer, FTIR and XRD were compared with those of commercial calcium carbonate. Results: The results showed that the isolation produced 98.5±0.5 % of calcium carbonate. The calcium carbonate powder had an average size of 21±1.0 µm, while that of commercial was 8±1.3 µm. The resulted calcium carbonate revealed similar XRD patterns compared with that from commercial Calcium carbonate from the market. Based on database from FTIR instrument, the calcium carbonate sample had 99% similarity level compared with that from the reference. The sample of Calcium carbonate isolated from the eggshell (>mesh 100) had lower antacid activity (23.83 mEq) than that of commercial (24.56 mEq). Conclusion: Calcium carbonate from eggshell fulfilled the requirements of Indonesian Pharmacopoeia.

Nano-Hydroxyapatite Isolation and Characterisation of Echinometra mathaei from the Persian Gulf.

The study focuses on the preparation and characterisation (physicochemical and mechanical) of hydroxyapatite [Ca10(PO4)6(OH)2] (HA) from sea urchin, Echinometra mathaei. Therefore, nano-sized HA prepared from sea urchin shells were collected from beaches of the Persian Gulf in Iran. Sea urchin shells were found a source of calcium carbonate in the form of aragonite (calcite) that crystallised in an organic matrix. HA is one of the polymers used in coating the nanoparticles extracted from various sources. The calcined aragonite converted to nanosized hydroxyapatite powder by chemical reaction with orthophosphoric acid while maintaining stoichiometry, Ca/P = 1.667 at 80°C. To determine the purity of the nano-hydroxyapatite (nHA) numerous analytical procedures were used. Fourier transforms infrared spectroscopy (FTIR) confirmed the presence of the peak of 961 cm-1 is related to the symmetric tensile band of the P-O bond, and the peak of 1038 cm-1 and 1091 cm-1 is related to the tensile solid absorption of the PO4 as functional groups of nHA. The nanocrystalline HA can be observed from the SEM images. Thermogravimetric analysis (TGA-DTA) demonstrates the thermal stability of nHA powder. The results show successful isolation and characterisation study of this crucial nano-material shows it is valuable in biomedical applications, particularly in bone tissue engineering. Indeed, its fabrication is easy and economical.

Bio-Based White Eggshell as a Value-Added Filler in Poly(Lactic Acid) Composites

Based on its positive environmental impact, poly(lactic acid) (PLA) has been a gradual substitute for synthetic plastics used in diverse applications. The use of industrial limestone (ILS) as a filler in polymers can have advantages of changing the properties of pure polymers. Waste eggshells (WE) can be seen as an alternative filler to ILS as they are also a source of calcium carbonate. To assess the feasibility of both filler types and sizes, PLA composites were manufactured by injection molding with filler contents of 5, 10, and 20 wt.%. Tensile, flexural, and impact mechanical properties were evaluated in addition to water absorption. One-way analysis of variance (ANOVA) was performed to determine whether statistically significant differences among the measured mechanical properties existed. Scanning electron microscopy (SEM) was used to view the morphology of the fillers and fractured surfaces. The composite tensile strengths and flexural strengths performed the best when filler loadings were 5 wt.% and 10 wt.%, respectively, for both filler types. The tensile and flexural modulus both increased with filler loadings. The impact strength for the composites was obtained at a threshold level of 5 wt.% filler loadings for both filler types and slightly better for smaller particles sizes. ANOVA identified statistically significant differences for the mean mechanical property values evaluated. SEM showed the fractured surfaces of the PLA composites were different from the pure PLA indicating some transformation occurred to the matrix. The weight gains due to water absorption were observed to increase with increase in content of both filler types while the smaller particles had slightly higher water weight gains. Although the composites containing ILS fillers had somewhat enhanced mechanical properties over the WE-filled composites, the end application will dictate which filler type to use in PLA.

Eco-friendly belite cement elaborated from shell and glass powder

The purpose of this study is to use inorganic wastes to completely replace traditional raw materials for the production of belite rich clinkers, waste glass as a source of SiO2 oxide and shells as a source of calcium carbonate CaCO3 to synthesize belite-rich cement. After grinding, the raw materials were blended to synthesize the dicalcium silicate phase (Ca2SiO4) in a heat treatment up to 1000 °C. The clinkers produced were rich in elaborated Ca2SiO4, mixed with gypsum and shell powder as a source of calcium carbonate to form belitic cements. The cements were prepared and hydrated with different proportions of belitic clinker (56, 62 and 72%).The specimens were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The results of the XRD and FTIR analyses demonstrate that hydration of the three cements over time leads to the formation of crystallized C-S-H compounds, which increase in abundance after 90 days upon the increase of the C2S percentage. We have attempted here to provide an update on the development of high-belite cements with low CO2 emissions.

Investigation of CaO/MgO on the formation of Anorthite, Diopside, Wollastonite and Gehlenite phases in the fabrication of fast firing ceramic tiles

In this research, the effect of CaO/MgO ratio as the principal oxides activating reactions during fast firing of ceramic tiles on the transformations and formation of phases such as Anorthite, Diopside, Wollastonite, and Gehlenite was studied. Calcium carbonate and Talc/dolomite powder were selected as the sources of CaO and MgO, respectively. After forming with the press, the mixtures were dried, and the bodies were sintered. XRD, XRF, Dilatometry, and SEM/FESEM analysis methods were used to study the microstructural transformations, chemical and physical reactions in the microstructure, and final physical properties of the samples. The X-ray diffraction test identified the phases of the constructed bodies. The weight percentage of the constituent phases was calculated using the MAUD software. Studies indicated that the weight percentage of the Anorthite phase increased by decreasing the CaO/MgO ratio. In addition, the thermal expansion coefficient decreased with the reduction of the CaO/MgO ratio. The lowest coefficient of thermal expansion (7.69 × 10-6 (1/°C)) was reported. Microstructural studies demonstrated that the harmful phase of Gehlenite was removed from the final microstructure, and the Anorthite phase was increased (up to 10 wt%) by fine-graining the primary sources of calcium carbonate and Talc. Furthermore, crystals of the Anorthite phase grew more.