Wollastonite Addition Research Articles

Wollastonite addition stimulates soil organic carbon mineralization: Evidences from 12 land-use types in subtropical China

Enhanced rock weathering through adding silicate rock powder to soil has been increasingly considered as an effective means of removing CO2 from the atmosphere. However, the potential impact of silicate rock powder addition on the stability of soil organic carbon remains largely unknown, which adds an uncertainty to its effectiveness in mitigating atmospheric CO2. In this study, the response of soil CO2 efflux to wollastonite addition was evaluated for 12 land-use types in a subtropical region of China through an incubation experiment. Results showed that wollastonite addition significantly (P < 0.05) increased soil CO2 efflux over the control by an average of 330.97 ± 29.25% during the incubation period. Approximately 90% of the variance in soil CO2 efflux was explained by soil properties in this study. Increased soil pH, dissolved organic carbon and available silicon induced by wollastonite addition were the main reasons responsible for the increase in soil CO2 emission. Soils having lower pH values responded to wollastonite addition with a higher increase in CO2 emissions. Based on numerous land-use types, our study showed that wollastonite application will cause substantial increase in the mineralization of soil organic carbon in acidic soil, which may weaken the effectiveness of enhanced rock weathering strategies as a tool for CO2 sequestration.

Near-zero sintering shrinkage in pottery with wollastonite addition

The precise control of the geometry of pottery is a challenge owing to the undesirable shrinkage and deformation observed after firing. In this study, near-zero sintering shrinkage pottery (NZS) with the sintering shrinkage (SS) of < 2.0% and pyroplastic deformation index (PI) of < 1.5 × 10−6 mm−1 was developed with varying amounts of added alumina and wollastonite. Wollastonite promotes anorthite crystallisation, thereby preventing sintering shrinkage at ∼1200 °C. The mechanism for the suppressed liquid-phase sintering of the pottery was also analysed. Moreover, NZS were obtained after firing at 1300 °C with a specific phase composition for suppressing the pyroplastic deformation. Thus, NZS was successfully prepared through liquid sintering from natural minerals. Therefore, this study provides a guide for the fabrication of earthenware, stoneware, unglazed porcelain and ceramic tiles with precise dimension and geometry. Additionally, it is also important for reducing the production loss in huge pottery and large-scale production by countering the sintering shrinkage.

Biological, physical, and chemical properties of wallostonite-added β-SiAlON ceramics

The different content of wollastonite was added to raw materials to prepare β-SiAlON ceramics; furthermore, in this study, the effect of wollastonite on the physical, chemical, and biological properties of β-SiAlON was explored. X-ray diffraction and scanning electron microscopy (SEM) demonstrated that Ca in β-SiAlON was uniformly distributed; however, the addition of wollastonite did not lead to the formation of the Ca-α-SiAlON phase. Wollastonite addition improved the sintering performance and increased the compressive strength of β-SiAlON ceramics. Moreover, SEM demonstrated that by adding wollastonite, the bonding of the sample became tighter. Ion release results demonstrated that the material had low ion release and stable chemical properties. Moreover, in cellular experiments, when the content of wollastonite is <12 wt% in β-SiAlON ceramics, β-SiAlON ceramics with or without Ca demonstrated satisfactory biocompatibility. The presence of some amount of Ca did not affect the adhesion, spreading, and proliferation of the MC3T3-E1 cells. Moreover, when wollastonite is <12 wt%, culturing MC3T3-E1 cells in the leaching solution of β-SiAlON ceramics confirmed that bone formation is unaffected. Thus, β-SiAlON ceramics containing Ca (wollastonite <12 wt%) demonstrated good physical and chemical properties; however, the biological properties remain unaffected. Therefore, the ceramics that were prepared are bioactive materials having excellent properties.

Preparation and fireproofing performance of the wollastonite-metakaolin-based geopolymer foams

This paper aims to investigate the physical properties and fire resistance of wollastonite-metakaolin-based geopolymer foams (WMGFs). Both compressive and flexure strengths of WMGFs are significantly improved since wollastonite fibers possess inherent stiffness and provide effective crack control. Meanwhile, wollastonite addition promotes viscosity of geopolymer slurry to some extent and then determines pores formation in foaming process, which is also crucial for mechanical strength development. The thermal conductivity of the specimens rises triflingly with elevated wollastonite addition corresponding to slightly decrease in porosity. Owing to the steady skeleton structure of WMGFs, the highest reverse-side temperature of sliced blocks is merely 202.7 °C after exposed to fire for 3 h, showing that the reduction in thermal conductivity has no negative impact on fire resistance of specimens. Physicochemical stability of wollastonite under high temperature and alkaline environment is confirmed to be vital for sustaining integrated porous skeleton structure of geopolymer foams. Therefore, geopolymer foams reinforced by wollastonite possess extraordinary mechanical strength and fire resistance, revealing strong possibility for fire protection.

Minimization of water absorption and pyroplastic deformation of wollastonite-containing alumina-strengthened porcelain

ABSTRACT The densification and pyroplastic deformation of alumina-strengthened porcelain were examined within a range of alumina and wollastonite contents. Both the alumina addition and anorthite crystallization not only prevent the liquid-phase sintering, which plays an important role in the densification of the porcelain during firing, but also suppress the pyroplastic deformation at high firing temperatures. The prevention of densification as well as the suppression of pyroplastic deformation is basically described by the change in the amount of liquid phase at firing. As a result, optimization between small water absorption and small pyroplastic deformation was found out in the relatively wide firing temperature range for porcelain with 30 mass% alumina addition and <10 mass% wollastonite addition. This study serves as a guide to achieve minimal water absorption and pyroplastic deformation in alumina-strengthened porcelain fired at temperatures from 1290 to 1380°C.

In-situ mineral CO2 sequestration in a methane producing microbial electrolysis cell treating sludge hydrolysate

Microbial electrolysis cell (MEC) has excellent CH4 production performance, however, CO2 still remains in the produced biogas at high content. For achieving in-situ CO2 sequestration and thus upgrading biogas, mineral carbonation was integrated into a MEC treating sludge hydrolysate. With 19 g/L wollastonite addition, in-situ mineral CO2 sequestration was achieved by formation of calcite precipitates. CH4 content in the biogas was increased by 5.1 % and reached 95.9 %, with CH4 production improved by 16.9 %. In addition, the removals of polysaccharide, protein, and chemical oxygen demand (COD) of the MEC were increased by 4.4 %, 6.7 %, and 8.4 %, respectively. The generated precipitates rarely accumulated on bio-cathode, and did not significantly affect the morphology of cathode biofilm. However, integrating mineral carbonation resulted in a higher relative abundance of Methanosarcina on anode and slightly decreased the ratio of Methanobacterium to Methanosaeta on cathode, which should be noticed. In conclusion, integrating mineral carbonation is an attractive way to improve the performance of MEC by achieving in-situ CO2 sequestration, accompanied with CH4 production enhancement.

Carbon dioxide sequestration and methane production promotion by wollastonite in sludge anaerobic digestion

This study investigated the feasibility and performance of simultaneous in-situ CO2 sequestration and CH4 production promotion by wollastonite addition in sludge AD. A maximum CH4 yield increment of 30.8% and maximum methane production rate increment of 64.9% with wollastonite addition at dosage of 16.25 g/L were achieved. CO2 was efficient sequestered by wollastonite addition and resulted in a higher CH4 content of 81.7%–82.4%. The mechanism of CO2 sequestration by wollastonite was confirmed as Ca2+ release and subsequently carbonation based on cation and precipitates analysis. The results demonstrated that wollastonite could be applied as an effective additive for simultaneous in-situ CO2 sequestration and CH4 production promotion of sludge AD.

Preparation and in vitro apatite-forming ability of hydroxyapatite and β-wollastonite composite materials

This paper provides a one-step method of preparation of the ceramic powders, containing various amounts of hydroxyapatite (HA) and β-wollastonite (WT), based on the salt coprecipitation and subsequent thermal treatment of the synthesis products at 1000 °C. Aqueous solutions of Ca(OH)2, H3PO4 and Na2SiO3 were used as precursors of Ca10(PO4)6(OH)2 and β-CaSiO3, as a minimal amount of by-product is formed during such an interaction of reagents. Variation of the concentration of the initial reagents allows the preparation of ceramic powders containing from 0 to 100 wt% of apatite. All composites were examined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), laser diffraction analysis and an adsorption method (BET). Degradability of composite powders was analyzed in the Tris-HCl buffer solution. The apatite-forming ability of synthetic composites was investigated by soaking composite ceramics in a simulated body fluid (SBF). The results that were obtained reveal an increase in the dissolution rate of powders with wollastonite addition. Soaking of the composite ceramics in SBF leads to the formation of a bone-like apatite spherical particle layer on their surfaces, which become thicker while the content of β-СаSiO3 in the samples increases.

Development and Characteristics of Anorthite-Based Traditional Ceramic Materials to Suppress Sintering Deformation

An anorthite-based traditional ceramic was developed by adding secondary flux materials to a mixture of kaolin and CaCO₃ in order to minimize the deformation during the sintering process. Three flux materials, feldspar, talc, and frit, were evaluated by comparison with two commercial chinaware bodies. Anorthite body with glass frit exhibited poor firing shrinkage. Poor mechanical properties (modulus of rupture, MOR ＜ 30 ㎫) was observed for the bodies with feldspar. Another anorthite body was formulated with wollastonite as a Ca source. The fired body showed a MOR of 81 ㎫ and a shrinkage rate of 6% when wollastonite was added up to 50%. In the XRD analysis, the phase ratio between anorthite and quartz was the highest in the specimen with 50% wollastonite addition. Homogeneous and relatively small closed pores were observed in the microstructural analysis. These results suggest that a ceramic body formulated with 50% kaolin and 50% wollastonite can be fired at 1200℃ with a 6% firing shrinkage rate, giving rise to minimal sintering deformation.

Long-term responses in soil solution and stream-water chemistry at Hubbard Brook after experimental addition of wollastonite

Environmental context Calcium silicate was added to a forest watershed in New Hampshire, USA, to accelerate its recovery from acid rain. The acid–base status of soil and stream quality improved over the 12-year study, with the most pronounced response in the upper elevation and the upper soil of the watershed. A total of 95% of the added calcium and 87% of the added silica were retained in the watershed over the study period. Abstract In October 1999, 3450kgha–1 of wollastonite (CaSiO3) was applied to Watershed 1 at the Hubbard Brook Experimental Forest in New Hampshire, USA, with the objective of restoring calcium that had been depleted from soil-exchange sites by chronic inputs of acid deposition. After the treatment, the concentrations and fluxes of calcium and dissolved silica significantly increased in both soil solution and stream water throughout Watershed 1, as did the acid-neutralising capacity. The concentrations and fluxes of inorganic monomeric aluminium significantly decreased. The treatment improved the acid–base status and decreased the potential for aluminium toxicity in stream water, especially in the lower reaches of the watershed. Approximately 4.7% of the added calcium and 17% of the added silica from the wollastonite treatment was exported from Watershed 1 in stream water by the end of 2010. Meanwhile, ~1825mmolm–2 of the added calcium and 2125mmolm–2 of the added silica were either transported to lower mineral soil horizons – as particulate wollastonite, or as dissolved solutes (calcium 77.6mmolm–2; silica 592.2mmolm–2), thus contributing to increases in soil pools – or were taken up by vegetation and incorporated into internal calcium and silica cycles of the watershed ecosystem. This experimental wollastonite addition was an effective tool for mitigating the acidification of the ecosystem and restoring the calcium status and forest health of this base-poor watershed.

Synergistic improvement of crop physiological status by combination of cadmium immobilization and micronutrient fertilization.

Wollastonite application in cadmium-contaminated soils can reduce cadmium concentrations in plant, while the side effect is the synchronous immobilization of micronutrients, which reduces micronutrient uptake in plant, inducing micronutrient deficient symptoms. Accordingly, we investigated whether the supplement of Zn and Mn fertilizers after the wollastonite addition could promote the growth and photosynthesis in amaranth (Amaranthus tricolor L.). In this study, plants were cultivated in cadmium-contaminated soil under micronutrient fertilization alone, wollastonite addition, and combination of wollastonite and micronutrient fertilization treatments. Then, plant biomass; photosynthesis parameters; and total Cd, Zn, and Mn concentrations were investigated. Moreover, chemical extractions were performed on soil samples. The results show that application of wollastonite decreased Cd, Zn, and Mn concentrations in plant and availability in soil and it increased the gas exchange ability of plants. But, it reduced the chlorophyll content in leaves and had no positive influence on plant biomass. In comparison, Zn and Mn fertilization after wollastonite application greatly increased plant biomass and photosynthetic ability. It also reduced Cd phytoavailability more efficiently. Therefore, synergistic improvement of physiological status of farmland crop by sequential treatment with first wollastonite for cadmium immobilization, and then micronutrient fertilization to avoid micronutrient deficiency, was demonstrated.

The resistance to high temperature of magnesia phosphate cement paste containing wollastonite

This paper aims to study the effect of wollastonite addition on the behavior of magnesium ammonium phosphate cement (MAPC) and magnesium potassium phosphate cement (MKPC) pastes exposed to different high temperatures. Different dosages of wollastonite were added to replace MgO powder in these two types of magnesia phosphate cements. The paste specimens were exposed to 105 °C for 24 h and to different temperatures of 200, 400, 600, 800 and 1000 °C for 3 h and then cooled to room temperature for different tests including mass loss, visual appearance, compressive strength, mineral composition and microstructure observation. The results show that the specimens containing 10 % wollastonite for both MAPC and MKPC mixtures presents the most improved high temperature resistance due to the excellent heat stability of wollastonite mineral and the refined microstructure. And the addition wollastonite has little influence on the hydration products of these two magnesia phosphate cements. Therefore, the incorporation of wollastonite is a potential method to improve the heat-resistance of MAPC or MKPC.

Effect of wollastonite addition on sintering of hard porcelain

Hard porcelain body with wollastonite additive was produced by the slip casting method using quartz, potassium feldspar and kaolin raw materials. Wollastonite powders were added to the porcelain formulation by replacing the potassium feldspar up to 5wt% to explore its effect on the sintering behaviour and also technological properties of as sintered end products. By means of rheological behaviour optimization of ceramic suspensions using several dispersants and sintering enhancement by wollastonite addition, hard porcelain of higher strength at lower firing temperature was obtained. By studying the effect of the additive concentration, on the firing temperatures of the hard porcelain, it is found that reducing firing temperature 25°C without compromising its quality and thereby producing energy saving was achieved by 1wt% wollastonite addition.

Strategies to control the high temperature shrinkage of fly ash based geopolymers

Abstract Strategies to control thermally induced shrinkage in fly ash based geopolymers are investigated. The use of low ( 100 MPa). Wollastonite addition also improved the flexural strength of the samples which was attributed to its acicular shape imparting fibre-like qualities. Microstructural investigations showed that unfired samples predominantly consisted of spherical particles coated with reaction product. Firing to 1000 °C converted the morphology to a more compact phase with increased pore size.

Durability of Concrete Containing Wollastonite and Fly Ash

A series of experiments were carried out to investigate the effect of wollastonite and fly ash combination on the compressive strength, flexural strength, modulus of elasticity, coming off amount, loss percentage of dynamic elastic modulus as well as surface scaling of concrete. The studies show that the effect of mixing wollastonite and fly ash can reach excellent mechanical and durability performance. The effect of mixing wollastonite and fly ash improve the mechanical and durability is better than mixing fly ash alone. The concrete mixes containing wollastonite and fly ash indicated that wollastonite addition 15% was found advantageous in improving concrete quality.

Watershed-Level Responses to Calcium Silicate Treatment in a Northern Hardwood Forest

Watershed 1 (W1) at the Hubbard Brook Experimental Forest in New Hampshire, with chronically low pH and acid neutralizing capacity (ANC) in surface water, was experimentally treated with calcium silicate (CaSiO3; wollastonite) in October 1999 to assess the role of calcium (Ca) supply in the structure and function of base-poor forest ecosystems. Wollastonite addition significantly increased the concentrations and fluxes of Ca, dissolved silica (Si), and ANC and decreased the concentrations and fluxes of inorganic monomeric Al (Ali) and hydrogen ion (H+) in both soil solution and stream water in all sub-watersheds of W1. Mass balances indicate that 54% of the added Ca remained undissolved or was retained by vegetation during the first 6 years after treatment. Of the remaining added Ca, 44% was retained on O horizon cation exchange sites. The Ca:Si ratio in the dissolution products was greater than 2.0, more than twice the molar ratio in the applied wollastonite. This suggests that Ca was preferentially leached from the applied wollastonite and/or Si was immobilized by secondary mineral formation. Approximately 2% of the added Ca and 7% of the added Si were exported from W1 in streamwater in the first 6 years after treatment. Watershed-scale Ca amendment with wollastonite appears to be an effective approach to mitigating effects of acidic deposition. Not only does it appear to alleviate acidification stress to forest vegetation, but it also provides for the long-term supply of ANC to acid-impacted rivers and lakes downstream.

Patterns of Ca/Sr and 87Sr/86Sr variation before and after a whole watershed CaSiO3 addition at the Hubbard Brook Experimental Forest, USA

Abstract Forty-one metric tons of the mineral wollastonite (CaSiO3) was applied to an 11.8 hectare watershed at the Hubbard Brook Experimental Forest (HBEF; White Mountains, New Hampshire, USA) with the goal of restoring the Ca estimated to have been depleted from the soil exchange complex by acid deposition. This experiment provided an opportunity to gain qualitative information on whole watershed hydrologic flow paths by studying the response of stream water chemistry to the addition of Ca. Because the Ca/Sr and 87Sr/86Sr ratios of wollastonite strongly contrast that of other Ca sources in the watershed, the wollastonite-derived Ca can be identified and its amount estimated in various ecosystem components. Stream water chemistry at the HBEF varies seasonally due to shifts in the proportion of base flow and interflow. Prior to the wollastonite application, seasonal variations in 87Sr/86Sr ratios indicated that 87Sr/86Sr was higher during base flow than interflow, due largely to greater amounts of biotite weathering along deeper flow paths. After the application, Ca/Sr and 87Sr/86Sr changed markedly as the high Ca/Sr and low 87Sr/86Sr wollastonite dissolved and mixed with stream water. The Ca addition provided information on the response times of various flow paths and ion exchange processes to Ca addition in this small upland watershed. During the first year after the addition, wollastonite applied to the near stream zone dissolved and was partially immobilized by cation exchange sites in the hyporheic zone. In the second and third years after the addition we infer that much of this Ca and Sr was subsequently desorbed from the hyporheic zone and was exported from the watershed in stream flow. In the fourth through ninth years after the addition, Ca and Sr from wollastonite that had dissolved in upland soils was transported to the stream by interflow during wet periods when the ground water table was elevated. Between years three and nine the minimum annual Ca/Sr ratio (in late summer base flow) increased, providing evidence that Ca and Sr had increasingly infiltrated to the deepest flow paths. Strong seasonal variations in Ca/Sr and 87Sr/86Sr ratios of stream water resulted from the wollastonite addition to upland forest soils, and these ratios have become sensitive to changing flow paths during the annual cycle. Most notably, high flow events now produce large excursions in stream geochemistry toward the high Ca/Sr and low 87Sr/86Sr ratios of wollastonite. Nine years after the application we estimate that ∼360 kg of Ca from wollastonite has been exported from the watershed in stream flow. The rate of export of Ca from wollastonite dissolution has stabilized at about 11 kg of Ca per year, which accounts for ∼30% of the dissolved Ca in the stream water. Given that 19 metric tons of Ca were applied to the watershed, and assuming this current rate of loss, it should take over 1000 years for this added Ca to be transported from the watershed.

Crystallization behavior of non-alkali glasses in the SiO 2[sbnd]CaO [sbnd]Al 2O 3[sbnd]ZnO [sbnd]TiO 2[sbnd]B 2O 3 system

The crystallization behavior of non-alkali glass in the SiO2 CaO Al2O3 ZnO TiO2 B2O3 system was investigated. Differential thermal analysis data of the base glass showed double exothermic peaks, one at a lower temperature with precipitation of anorthite (CaO·Al2O3·2SiO2) and gehlenite (2CaO·Al2O3·SiO2), the other at a higher temperature with precipitation of willemite (2ZnO·SiO2) and titanite (CaO·TiO2·SiO2). Phase separation of the glass into an Al2O3-rich glass phase and a TiO2 + ZnO-rich glass phase prior to crystallization was confirmed. The effect of additives and water vapor soaking on surface crystallization of the glass were tested to find a best way to promote the crystallization of the glass. Wollastonite (CaO·SiO2) addition proved most effective, shifting the double peaks of DTA curve into a single one. A similar effect was observed with water vapor exposure of the glass. It was revealed from SEM analyses that the glass-ceramics body consisted of four types of crystals of small grain size.