CaSO4 Research Articles

Preparation of calcium sulfate from recycled red gypsum to neutralize acidic wastewater and application of high silica residue

Preparation of calcium sulfate from recycled red gypsum to neutralize acidic wastewater and application of high silica residue

Enhancing the eco-friendly use of manganese sulfate residue via recognition and reconstruction of metastable structure

Long-term accumulation of manganese sulfate residue can lead to the release of soluble manganese ions, which in turn can contaminate the surrounding environment. However, effectively guiding the treatment of soluble manganese in manganese sulfate residue is challenging due to limited understanding of its metastable structure. In this study, the metastable phase of manganese sulfate residue was analyzed by transmission electron microscope (TEM), cross-reaction X-ray energy dispersive spectroscopy (EDS) and X-ray diffractometer (XRD). The results reveal that the metastable phase within manganese sulfate residue consists of amorphous hydroxide and calcium sulfate. Furthermore, the amorphous hydroxide colloid is coated by calcium sulfate. The reconstruction of the metastable structural phase in manganese sulfate residue was achieved by adding BaCO3. The toxic leaching of the residue after phase reconstruction was assessed. The results show that the lowest leaching concentration of Mn and Ba were 0.6737 mg L−1 and 1.778 mg L−1, respectively. The leaching amounts of Mn and Ba were within the allowable range of GB 8978–1996 and GB 5085.3–2007, respectively. This suggests that the addition of BaCO3 can achieve harmless of manganese sulfate residue. Finally, the reconstructed residue is used to prepare the unfired brick with wave-absorbing. The obtained results show that the compressive strength of the brick is 17.00 MPa, meeting the standard of MU15. Additionally, the minimum reflection loss value of the brick is −10.51 dB, showing that the material has promising ability in absorbing wave.

Source Apportionment of PM10 as a Tool for Environmental Sustainability in Three School Districts of Lecce (Apulia)

Air pollution is a great threat to the sustainable development of the world; therefore, the improvement of air quality through the identification and apportionment of emission sources is a significant tool to reach sustainability. Single particle analysis, by means of a scanning electron microscope equipped with X-ray energy dispersive analysis (SEM-EDS), was used to identify the morphological and chemical properties of the PM10 particles in order to identify and quantify the main emission sources in three areas of Lecce, a city in the Apulia region of southern Italy. This type of characterization has not yet been performed for the Lecce site, but it is of particular importance to identify, based on the shape of the particles, the natural sources from the anthropogenic sources that are responsible for the serious health effects of the inhabitants. Three primary schools located in peripheral areas of the city were chosen for the sampling: “School 1” (A site), “School 2” (B site), and “School 3” (C site) to carry out a study of the air quality. The A site is characterized by a greater presence of calcium sulphates probably due both to construction activities present during sampling and to reactions between Ca particles and the sulfur present in the atmosphere. At the C site, there is a relative numerical abundance of different groups of particles that present, in the EDS spectrum, an enrichment in sulfur. At the B site, the number of particle groups is intermediate compared to that of the other two sites. With the source apportionment technique, ten emission sources were identified: combustion, soot, industry, soil, carbonates, sea salt, calcium sulfates, SIA, biological particles, and others. In PM10, the three sites are more affected by the soil source, with an effect greater than 60%.

Nano-micron soda residue as green nucleation seeding additive for silicate cement

Soda residue (SR) is a kind of by-product by the ammonia-alkali process in the soda ash production, which contains calcium components, such as calcium sulfate and calcium chloride. In this work, the feasibility of using SR as an accelerating additive for Portland cement (PC) was investigated. Wet milling method was used to prepare nano-micron SR seed with D50 of 246 nm. A binary system of PC and SR seed was designed, and its compressive strength, hydration kinetics and microstructure were studied. Results showed that the 12-hour compressive strength of PC was greatly increased by 1.69 times when the dosage of SR seed was 6%. This improvement was attributed not only to the nucleation seeding and filling effect of the SR seed, but also to the presence of pre-dissolved chlorine and sulfate ions from SR particles. Furthermore, the pore volume was reduced by more than 16%, the critical pre radius was decreased by 86.3%, and the gel pore content was 2.3 times that of reference group, indicating a high microstructure refinement and gel binding contribution of SR seed.

Mechanical strength measurement of needle-shaped CaSO4 microcrystals by a three-point bend test

A simple method for direct measurement of the mechanical strength of needle-shaped microcrystals of calcium sulfate, CaSO4, is proposed. The microcrystals, with a length from 30 to 50 μm and transverse dimensions from 1 to 3 μm, can act as reinforcing filler in various structural and building composites to improve their mechanical properties. The method is based on a three-point bend test, adapted to microscopic objects. The CaSO4 microcrystals were placed on a substrate, which was a twill-weave filter mesh consisting of intertwined steel fibers with diameter of ∼25 μm. Due to the twill weave, the mesh surface is characterized by a periodic distribution of protrusions and depressions. The protrusions act as supports for the placing of microcrystals, and the depressions provide the possibility of deformation and destruction of microcrystals under the action of an increasing vertically acting force, which is applied to the microcrystal through the indenter of the dynamic ultra-micro hardness tester. The moment of destruction of the microcrystals is observed to be dependent on the force on the displacement of the indenter. The measured values of the mechanical strength of CaSO4 microcrystals varied in a range from ∼3.5 to ∼6.0 GPa. The experimental strength values are in good agreement with the values obtained from the results of numerical analysis of the stressed state formed in the volume of CaSO4 microcrystals during the three-point bend test.

Effect and mechanism of freezing on the quality and structure of soymilk gel induced by different salt ions.

The increasing attention toward frozen soy-based foods has sparked interest. Variations exist in the quality and structure of soymilk gels induced by different salt ions, leading to diverse changes post-freezing. This study compared and analyzed the effects of calcium chloride (CC), magnesium chloride (MC) and calcium sulfate (CS) on the quality characteristics and protein structure changes of soymilk gels (CC-S, MC-S and CS-S) before and after freezing, and clarified the mechanisms of freezing on soymilk gel. The formation rate of soymilk gel is influenced by the type of salt ions. In comparison to CS and MC, soymilk gel induced by CC exhibited the fastest formation rate, highest gel hardness, lowest moisture content, and smaller gel pores. However, freezing treatment deteriorated the quality of soymilk gel induced by different salt ions, leading to a decline in textural properties (hardness and chewiness). Among these, the textual state of CC-induced soymilk gel remained optimal, exhibiting the least apparent damage and minimal cooking loss. Freezing treatments prompt a transition of soymilk gel secondary structure from β-turns to β-sheets, disrupting the protein's tertiary structure. Furthermore, freezing treatments also fostered the crosslinking between soymilk gel protein, increasing the content of disulfide bonds. The quality of frozen soymilk gel is influenced by the rate of gel formation induced by salt ions. After freezing, soymilk gel with faster gelation rates exhibited a greater tendency for the transformation of protein-water interactions into protein-protein interactions. They showed a higher degree of disulfide bond formation, resulting in a more tightly knit and firm frozen gel network structure with denser and more uniformly distributed pores. © 2024 Society of Chemical Industry.

Experimental study of mechanistic factors influencing solvent-driven fractional crystallization of calcium sulfate

To advance dimethyl ether-driven fractional crystallization (DME-FC), a more sustainable method of water treatment and mineral recovery, a range of chemical equilibria were measured. These include varying concentrations of miscible organic solvents (MOS) used to experimentally measure the solvent-induced solid-liquid equilibrium (SLE) of calcium sulfate (CaSO4) in water. Seven MOS, including dimethyl ether (DME), acetonitrile (MeCN), 1,4-dioxane, tetrahydrofuran (THF), acetone, ethanol, and diethylamine, were screened to establish trends associated with molecular volume, functional groups, and physical properties. The effect of MOS on CaSO4 removal differed at concentrations <0.15 mol fraction MOS; MOS with greater molecular volume (THF, 1,4-dioxane, and diethylamine) induced greater CaSO4 precipitation on a per mole basis. The solvent-induced SLE for all MOS converged between 0.15 and 0.2 mol fraction MOS, reaching a CaSO4 concentration consistent with a water to MOS hydration ratio of 5:1 to 6:1, which may correspond to the solvent generating a solution-based pseudo-clathrate structure with continuity within the solution. Solution pseudo-clathrate structures provide a mechanistic basis for DME-FC.

The impact of stoichiometry on the initial steps of crystal formation: Stability and lifetime of charged triple-ion complexes.

Minerals form in natural systems from solutions with varying ratios of their lattice ions, yet non-stoichiometric conditions have generally been overlooked in investigations of new formation (nucleation) of ionic crystals. Here, we investigated the influence of cation:anion ratio in the solution on the initial steps of nucleation by studying positively and negatively charged triple ion complexes and subsequent particle size evolution. Our model systems are carbonates and sulfates of calcium and barium, as it was recently shown that solution stoichiometry affects the timing and rate of their nucleation. Molecular dynamics (MD) simulations and dynamic light scattering (DLS) flow experiments show that nucleation correlates with the stability and lifetime of the initial complexes, which were significantly impacted by the cation:anion stoichiometry and ion type. Specifically, was found to have higher association constants and its lifetime was twofold longer than . Similar trends were observed for and . Contrastingly, for , was found to have lower association constants and its lifetime was shorter than . These trends in stability and lifetime follow the same asymmetrical behaviour as observed experimentally for particle formation using techniques like DLS. This suggests a causal relationship between the stability and lifetime of the initial charged complexes and the nucleation under non-stoichiometric conditions.

Using Different Extraction Methods to Estimate Soil Salinity and Salt Type Changes and Their Effects on Soil Inorganic Carbon in Plowed Desert–Sierozem Soil

Understanding the actual soil salt ion content and salt type is one of the important prerequisites for determining the nature of saline soils and their development and utilization in drylands. Desert–sierozem soils are widely distributed in the plains between the northern piedmont of the Tianshan Mountains and the Gurbantunggut Desert in Xinjiang, Northwest China, which contain abundant calcium sulfate (gypsum) and calcium carbonate and are high-quality arable land resources for agriculture. These soils have been extensively reclaimed for farmland in recent decades. In this study, 10 plots of desert–sierozem soils with different tillage years in the Qitai Oasis plain area in the northern piedmont of Tianshan Mountain were studied. Three soil profiles were excavated in each sample plot with a depth of 1.2 m. A total of 30 farmland profiles were dug up and sampling was conducted according to the soil occurrence layers of the farmland. All the soil samples were predominantly sandy in texture, with more than 92% of the soil particles distributed between 0.05 and 0.25 mm, and less than 8% between 0.002 and 0.05 mm. Conventional water extraction (CWE) and intensified water extraction (IWE) were adopted to extract the water-soluble salt ions content of K+, Na+, Ca2+, Mg2+, Cl−, SO42−, HCO3− and CO32−, and this study compared the extraction results using two different methods with varying extraction strengths. Additionally, the calcium sulfate and calcium carbonate contents were obtained using the chemical extraction and mineral assay methods, respectively. Differences in the salts and salt types in desert–sierozem soils with different tillage years were analyzed, and the effect of calcium sulfate on the inorganic carbon sinks in plowed desert–sierozem soil was demonstrated. The findings indicated that the standard conventional extraction procedure involving a 5:1 water–soil ratio and 3 min of shaking was inadequate for accurately measuring the soil salt content in high calcium sulfate content desert–sierozem soils. With the IWE method, by increasing the water–soil ratio, prolonging the shaking time, and grinding the particles finer, the amount of water-soluble salts extracted using the IWE method was 5.83 times higher than that of the conventional method. Among them, the average content of IWE-Mg2+ increased by 123.41 mg kg−1 compared to CWE-Mg2+, the average content of IWE-Ca2+ was 3.82 times higher than CWE-Ca2+, with an average increase of 2931.59 mg kg−1, and the IWE-SO42− content was 5.96 times higher than CWE-SO42−, with an average increase of 8658.95 mg kg−1. A markedly negative correlation (p &lt; 0.01) was observed between calcium carbonate and calcium sulfate in desert–sierozem soils after tillage. The calcium sulfate content consistently decreased and calcium carbonate increased with an increasing number of tillage years. The pedogenic calcium carbonate content in desert–sierozem soils increased by an average of 10.86 g kg−1 after more than 40 years of cultivation, and the transfer of Ca2+ from calcium sulfate to calcium carbonate was identified as the cause of the increase in the soil inorganic carbon sink. Overall, a new method for extracting water-soluble salts was utilized for aridisols, which commonly consist of complex salt types. The results elucidate the changes in salinity within plowed desert–sierozem soils as well as the impact of soil salt on soil inorganic carbon sinks. Based on our research, desert–sierozem soils are well suited for agricultural farming because they contain high levels of sulfate, which is one of the important inorganic nutrients essential for crops, and it also provides a source of calcium for increasing inorganic carbon sinks. This study serves as a reference and scientific basis for soil carbon cycles in arid zones.

CONTRIBUTION TO THE HYDROCHEMICAL STUDY OF GROUNDWATER IN THE PLAIN OF MELLAGOU - BOUHMAMA (NORTHEAST ALGERIA)

The groundwater of Bouhmama shows important chemical variations induced by the aridity of the climate, mineral dissolution and agricultural activity. The use of geochemical techniques has identified that the evolution of the chemical facies takes place from the calcium bicarbonate pole in the limestone outcrops in the West towards a major facies of calcium sulfate type in the center and downstream of the plain. These chemical facies are determined by the water-rock interaction, dissolution and mineral precipitations, through cationic exchanges along the water flow towards its outlet and the infiltration of irrigation waters loaded with salts and fertilizers in the irrigated perimeters. PCA (Principal Component Analysis) explaining 85.64% of the variance shows that except for bicarbonates all elements are responsible for the mineralization of groundwater

Partially sulfonated polystyrenes: A new gypsum superplasticizer

Calcium sulfate hemihydrate is widely used for gypsum product fabrication; however, it requires superplasticizers to improve its fluidity and workability. In this study, we aimed to develop a novel superplasticizer based on partially sulfonated polystyrene (PStSS-fSS) for calcium sulfate hemihydrate. We synthesized PStSS-fSS by polymerization of styrene and sodium 4-styrenesulfonate and compared its performance with polynapthalene sulfonate (PNS) in terms of fluidity, zeta potential, hydration rate, and water resistance. PStSS-fSS exhibited higher fluidity than PNS without hydration delay of hemihydrate. The higher fluidity was attributed to the enhanced polymer adsorption on the hemihydrate surface because of the hydrophobic units. PStSS-fSS also imparted better water-resist properties to the gypsum products. PStSS-fSS is confirmed as a better superplasticizer than PNS for calcium sulfate hemihydrate, providing higher fluidity and improved water resistance.

Elemental distributions of solid waste collected from the germanium extraction process.

The solid waste produced from the germanium extraction process has attached much attention to its potential germanium sources. However, the elemental distribution of solid waste is still unclear. Therefore, the solid waste was studied using a sequential extraction procedure and characterizations including XRD, FTIR, XPS, SEM-EDS, and XAFS. It has been found that Ca, S, Fe, and Si could present crystal occurrence forms such as calcium sulfate, iron oxide hydroxide, or quartz. Furthermore, Si and Al can form a certain amount of amorphous substance. Accordingly, the sequential leaching results tell that Ca and S can be mostly leached out in pure water or weak acid solution, and more than 50% of Fe, Al, and Si were leached out in the reducible or oxidizable environment. Additionally, a part of S could be associated with Pb, generating a mostly Pb-bearing sulfate structure. Most of Zn was leached out from the reducible step, and only a very small part of Zn presented in the residual state, indicating that the majority of Zn might exist in an oxidation state and a small amount of Zn is associated in the amorphous phase. In terms of Ge, As, and Cr, almost all of them existed in the residual state. Ge should be in the occurrence of Si/Al amorphous structure. Similarly, Cr should be most likely to associate with silicates. Furthermore, As is mainly associated with iron mineral through the formation of the binuclear bidentate corner-sharing complex.

Research on the inhibitory properties and mechanism of carboxymethyl cellulose-modified sulfur quantum dots towards calcium sulfate and calcium carbonate

An eco-friendly antimicrobial sulfur quantum dot scale inhibitor (CMC-SQDs) synthesized using carboxymethyl cellulose (CMC) showed strong inhibition of calcium sulfate (CaSO4) at a concentration just below 1 mg/L, with an inhibition efficiency exceeding 99 %. However, the precise interaction process between CMC-SQDs and CaSO4 remains unclear. This article investigates the effectiveness of SQDs in inhibiting the formation of CaSO4 and calcium carbonate (CaCO3) scales. Through static scale inhibition tests, molecular dynamics simulations, and quantum chemical calculations, the study aims to elucidate the different impacts of CMC-SQDs on CaSO4 and CaCO3 scale formation. The research focuses on understanding the relationship between the structural activity of CMC-SQDs and their scale-inhibiting performance and delving into the underlying mechanisms of scale inhibition. The findings describe the role of SQDs in a water-based solution, acting as persistent “nanodusts” that interact with calcium (Ca2+) ions and sulfate ions. CMC forms complexes with Ca2+ ions, and the presence of SQDs enhances the van der Waals force, indirectly increasing the resistance of associated ions and the binding energy on the surface of precipitated gypsum. Conversely, SQDs exhibit weak surface stability and have minimal binding energy when interacting with calcite, leading to limited occupation of available adsorption sites.

Comparison of different bone substitutes in the repair of rat calvaria critical size defects: questioning the need for alveolar ridge presentation.

This study aimed to evaluate the effectiveness of biomaterials in bone healing of critical bone defects created by piezoelectric surgery in rats calvaria. Histomorphological analysis was performed to assess bone regeneration and tissue response. Fifty animals were randomized into 5 groups with one of the following treatments: Control group (CO, n=10), spontaneous blood clot formation with no bone fill; BO group (Bio-Oss®, n=10), defects were filled with bovine medullary bone substitute; BF group (Bonefill®, n=10), defects were filled with bovine cortical bone substitute; hydroxyapatite group (HA, n=10), defects were filled with HA; calcium sulfate group (CS , n=10), defects were filled with CS. Five animals from each group were euthanized at 30 and 45 days. The histomorphometry calculated the percentage of the new bone formation in the bone defect. All data obtained were evaluated statistically considering P<0.05 as statistically significant. The results demonstrate the potential of all biomaterials for enhancing bone regeneration. The findings showed no statistical differences between all the biomaterials at 30 and 45 days including the control group without bone grafting. In conclusion, the tested biomaterials presented an estimated capacity of osteoconduction, statistically non-significant between them. In addition, the selection of biomaterial should consider the specific clinical aspect, resorption rates, size of the particle and desired bone healing responses. It is important to emphasize that in some cases, using no bone filler might provide comparable results with reduced cost and possible complications questioning the very frequent use of ridge presentation procedures.

Preparation of a High‐Performance Anti‐Aging Polypropylene Composite with Titanium Oxide and Calcium Sulfate Shielding Agents

AbstractPolypropylene is a thermoplastic synthetic resin that is widely used across industries. However, it tends to fracture easily and get oxidized under ultraviolet light and high temperatures. This not only reduces its service life but also causes pollution and waste. Although the use of TiO2 as a shielding agent has improved the aging performance of PP composite materials, it still has poor mechanical and processing properties that do not meet the actual demand for high‐performance polypropylene.This limitation seriously impacts the development of polypropylene products. In this paper, we propose the use of the ATRP method with UV shielding titanium dioxide (TiO2) and high‐toughness calcium sulfate whiskers (CSW) coated with coupling agent KH570 surface modification after grafting acrylonitrile (AN). This material has a dual shielding effect on UV light. TiO2‐PAN (TP) mainly plays the role of anti‐aging, whereas CSW‐PAN(CP) mainly enhances the compatibility and mechanical strength between TP and CP. Additionally, CP has a certain UV shielding function due to grafting acrylonitrile. When added to PP in a certain proportion, TP and CP work together to improve the overall performance of polypropylene.

Extraction of lithium and phosphorus from amblygonite using calcium sulfate roasting and water leaching

This work proposes the roasting of amblygonite with calcium sulfate followed by water leaching to extract lithium and phosphorus. Various roasting parameters including roasting temperature, the mass ratio CaSO4/ore, roasting time as well as leaching parameters, such as the liquid/solid ratio, temperature and time, have been carefully investigated. The lithium extraction efficiency can be as high as 99.8% with a mass ratio of CaSO4/ore of 0.85 after roasting at 775 °C for 1 h and water leaching at a liquid/solid ratio of 3 mL/g at 100 °C for 2 h. The XRD analysis demonstrates that the fluoride in the amblygonite can be converted into Ca5(PO4)3F and CaF2. Lithium in the leach liquor can be recovered as Li2CO3. Meanwhile, the phosphorus in the water leach residue can be recovered as FePO4 with a high recovery of 96.6% after acid dissolution and precipitation, which can be further treated to produce LiFePO4.

The effect of different antibiotic combinations in calcium sulfate cement on the growth of Cutibacterium acnes and Staphylococcus periprosthetic shoulder infection isolates

BackgroundProsthetic joint infections (PJI) of the shoulder are a devastating complication of shoulder arthroplasty and are commonly caused by Staphylococcus and Cutibacterium acnes. Absorbable calcium sulfate beads are sometimes used for delivering antibiotics in PJI. This study evaluates the in vitro effect of different combinations of gentamicin, vancomycin, and ertapenem in beads made from calcium sulfate cement on the growth of C. acnes and coagulase-negative Staphylococcus strains. MethodsThree strains of C. acnes and five strains of coagulase-negative Staphylococcus from clinically proven shoulder PJI were cultured and plated with calcium sulfate beads containing combinations of vancomycin, gentamicin, and ertapenem. Plates with C. acnes were incubated anaerobically while plates with Staphylococcus were incubated aerobically at 37°C. Zones of inhibition were measured at intervals of 3 and 7 days using a modified Kirby Bauer technique, and beads were moved to plates containing freshly streaked bacteria every 7th day. This process was run in triplicate over the course of 56 days. Statistical analysis was conducted using SPSS v. 28 with repeated measures ANOVA and pairwise comparisons with Tukey correction. ResultsIn experiments with C. acnes, beads containing ertapenem + vancomycin and vancomycin alone formed the largest zones of inhibition over time (p<.001). In experiments with Staphylococcus, beads containing vancomycin alone formed the largest zones of inhibition over time for all five strains (p<.001). Zones of inhibition were 1.4x larger for C. acnes than for Staphylococcus with beads containing vancomycin alone. For both C. acnes and Staphylococcus, beads containing ertapenem had the strongest initial effect, preventing all bacterial growth in C. acnes and almost all growth for Staphylococcus during the first week but dropping substantially by the second week. Beads containing gentamicin alone consistently created smaller zones of inhibition than beads containing vancomycin alone, with vancomycin producing zones 5.3x larger than gentamicin in C. acnes and 1.3x larger in Staphylococcus (p<.001). DiscussionThese data suggest that for both C. acnes and Staphylococcal species, calcium sulfate beads impregnated with vancomycin were most effective at producing a robust antibiotic effect. Additionally, ertapenem may be a viable supplement in order to create a more potent initial antibiotic effect but is not as effective as vancomycin when used alone. Gentamicin alone was not effective in maintaining consistent and long-term antibiotic effects. These results indicate that amongst the antibiotics currently commercially available to be used with calcium sulfate, vancomycin is consistently superior to gentamicin in the setting of C. acnes and coagulase negative Staphylococci.

Dynamic Scaling Prediction Model and Application in Near-Wellbore Formation of Ultradeep Natural Gas Reservoirs

Summary To address the significant scaling challenges within the near-wellbore formation of ultradeep natural gas reservoirs characterized by high temperature and high salinity, we developed a dynamic scaling prediction model. This model is specifically designed for the prediction of scaling in gas-water two-phase seepage within fractured-matrix dual-porosity reservoirs. It accounts for the concentration effects resulting from the evaporation of water on formation water ions. Our scaling model is discretely solved using the finite volume method. We also conducted on-site dynamic scaling simulations for gas wells, allowing us to precisely predict the distribution of ion concentrations in the reservoir, as well as changes in porosity and permeability properties, and the scaling law dynamics. The simulation results reveal a significant drop in formation pressure, decreasing from 105 MPa to 76.7 MPa after 7.5 years of production. The near-wellbore formation is particularly affected by severe scaling, mainly attributed to the radial pressure drop funneling effect, leading to a reduction in scaling ion concentrations in the vicinity of the wellbore. Calcium carbonate is identified as the predominant scaling component within the reservoir, while calcium sulfate serves as a secondary contributor, together accounting for roughly 85.2% of the total scaling deposits. In contrast, the scaling impact on the matrix system within the reservoir remains minimal. However, the central fracture system exhibits notable damage, with reductions of 71.2% in porosity and 59.8% in permeability. The fracture system within a 5-m radius around the wellbore is recognized as the primary area of scaling damage in the reservoir. The use of the simulation approach proposed in this study can offer valuable support for analyzing the dynamic scaling patterns in gasfield reservoirs and optimizing scaling mitigation processes.

Effects of Anhydrous Calcium Sulfate Whisker and Waste Engine Oil on Performance of Asphalt Binder and Its Mixture

Effects of Anhydrous Calcium Sulfate Whisker and Waste Engine Oil on Performance of Asphalt Binder and Its Mixture

Mechanical Activation of CaSO4 Enriched Petroleum Coke Fly Ash for Development of Green Pellets

Mechanical Activation of calcium sulphate enriched petroleum coke fly ash (PCFA) generated from circulation fluidized bed combustion (CFBC) boiler was investigated to improve the surface reactivity of PCFA. The physico- chemical, mineralogical (XRD), morphological (SEM) characteristics of PCFA, activated PCFA and developed green pellets were studied in detail. It was found that the milling time of 45 minutes is efficient for the activation of PCFA and results in fragmentation of coarse particle into fine porous particles. Mechanical activation results in enhancing physical properties and reactivity of PCFA without any further chemical treatment. The mean particle size of activated PCFA with 45 min milling time was 12.51-12.60µm and the porous morphology were seen through SEM. The hydration phases like ettringite, portlandite and calcium silicate hydrate mainly contribute to the development of mechanical strength in activated PCFA pellets which were also confirmed through morphology of needle-shaped crystallites. The study recommends that mechanically activated PCFA could be used as an adsorbent material for heavy metals removal from waste waters.