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Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrometallurgy of China is the property of Hydrometallurgy of China Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Secondary aluminum ash is a byproduct in the aluminum industry that contains valuable components, such as aluminum nitride (AlN) and aluminum oxide (Al2O3). AlN has excellent thermal and electrical properties and is widely used in various applications, making the recovery of AlN from secondary aluminum ash essential for both economic and environmental reasons. In this study, we developed a novel triboelectric separation technique to recover AlN from aluminum ash by investigating the tribocharging characteristics of the main components of secondary aluminum ash, Al2O3 and AlN. We studied the effects of tribocharging ball ratio, friction time, and stirring speed on the tribocharging of pure Al2O3 and AlN, using various materials such as polytef (PTFE), polypropylene (PP), polyvinyl chloride (PVC), copper (Cu), and stainless steel (SS) as tribocharging materials. We also examined the effects of friction medium ball ratio, friction medium material, rotational speed, and voltage on the triboelectric separation process. Our results showed that the charge-to-mass ratio for Al2O3 and AlN was 1.96 and −15.56 nC/g, respectively, the difference is largest, with a PTFE ball, a 1:5 ratio, a stirring speed of 290 n/min, and a tribocharging duration of 30 s. The triboelectric sequence of these friction materials was (+)PTFE, PP, Al2O3, SS, Cu, PVC, and AlN (-). To recover AlN from aluminum ash, PTFE should be chosen as the friction medium, and a friction medium ball ratio of 1:3, rpm rotation speed of 50, and voltage of 40kV should be used, resulting in an AlN grade of 89.25% and a significant increase in the recovery rate of AlN in the positive and negative electrode. Our findings demonstrate the feasibility of effective triboelectric separation of Al2O3 and AlN. [ABSTRACT FROM AUTHOR]

Secondary aluminum ash (SAA) is a hazardous solid waste generated in the process of recycling aluminum. The preparation of glass ceramic foams from high content of SAA, used as nucleating and foaming agent, was proposed to achieve green and comprehensive utilization of SAA. With the help of thermodynamic phase diagram and viscosity calculation, a mixture of SAA and waste glass (WG) were transformed, at 1200 °C for 30 min, into glass ceramic foams with porosity of 45.49%–59.45%, respectively. The mean pore size of the samples decreased from 2.89 to 1.53 mm with the decrease of SAA addition. Through the adjustment of temperature, it was found that the mixture had a microporous region at 1100 °C. The expansion region was observed at 1180 °C and 1200 °C, because of the oxidation of AlN in SAA. The porosity of the samples could be raised to 64.51%, with 5–9% B2O3 as a supplement, which contributed to the development of the liquid phase and a decrease in the melt's viscosity. The mechanism of in-situ isothermal foaming, nucleation, and crystallization of SAA and WG was clarified. The crystal intensity dropped and the amorphous phase became the primary phase at 800 °C. Al2O3, sodium silicate and sodium aluminum silicate precipitated at 1000 °C. Al2O3 and spinel with high melting point were wrapped by silicate. Silicate turned into the melt again as the temperature continued to rise. With the further reduction of viscosity, the gas diffused in crystalline and amorphous phases, and finally forms glass ceramic foams with hierarchical pore structure.

Secondary aluminum ash (SAA) is a type of common solid waste which leads to pollution without treatment. Due to its chemical reactivity, the application of SAA to reactive powder concrete (RPC) may help solidify this solid waste while increasing its performance. However, RPC is usually in active service when used with steel bars. NaCl can corrode the steel bars when reinforced RPC is used in a coastal environment. In this study, the corrosion resistance of reinforced RPC was investigated. The specimens were exposed to an environment of NaCl with freeze–thaw cycles (F-Cs) and dry–wet alternations (D-As). The corresponding mass loss rates (MRs), the electrochemical impedance spectroscopy (EIS) curves and the dynamic modulus of elasticity (DME) were measured. The results show that the MR and the DME of reinforced RPC decrease with increasing values of F-C and D-A. F-C and D-A increases lead to increased electrical resistance (R). The real part value corresponding to the extreme point of the EIS curve is increased by 0~213.7% when the SAA is added. The relationship between the imaginary part and the real part of the EIS fits the quadratic function. The equivalent circuit of the reinforced RPC is obtained from the EIS curves. The R of the rust is calculated by using the equivalent circuit. The rust's R decreases in the quadratic function with the mass ratio of the SAA. After 200 NaCl F-Cs, the MR, the DME and the R vary within the ranges of 23.4~113.6%, −2.93~−4.76% and 4.92~13.55%. When 20 NaCl D-As are finished, the MR, the DME and the R vary within the ranges of 34.7~202.8%, −13.21~−14.93% and 120.48~486.39%. The corrosion area rates are 2.3~68.7% and 28.7~125.6% higher after exposure to 200 NaCl F-Cs and 20 NaCl D-As. When the SAA is mixed, the MR is decreased by 0~13.12%, the DME increases by 0~3.11%, the R of the reinforced RPC increases by 26.01~152.43% and the corrosion area rates are decreased by 21.39~58.62%. This study will provide a novel method for solidifying SAA while improving the chlorine salt resistance of RPC. [ABSTRACT FROM AUTHOR]

Secondary aluminum ash is a kind of common solid waste which will pollute the environment without any treatment. In this study, the influence of secondary aluminum ash on the rheological properties and the initial setting time of fresh reactive powder concrete (RPC) are researched. Meanwhile, the mechanical properties and the drying shrinkage rates of RPC with the secondary aluminum ash are determined. The electrical parameters of RPC with the secondary aluminum ash are measured. Scanning electron microscopy is obtained to reflect the internal structure of RPC. Results show that the addition of secondary aluminum ash can lead to decreasing the fluidity and increase the yield shear stress of fresh RPC paste by varying rates of 16.1% and 58.3%, respectively. The addition of secondary aluminum ash can decrease the flexural and compressive strengths of RPC cured for 1 day by the decreasing rates of 0~18.7% and 0~19.3%. When the curing age is 28 days, the flexural and compressive strengths of RPC are increased by 0~9.1% and 0~19.1% with adding the secondary aluminum ash. The secondary aluminum ash can promote the condensation of RPC. The addition of the secondary aluminum ash can decrease the electrical resistance of RPC by an order of magnitude. The relationship between the electrical resistance and the electrical reactance fits the quadratic function equation. The electrical resistance of the pore solution increases in the form of a quadratic function with the mass ratio of the secondary aluminum ash. The dry shrinkage rates of RPC cured for 1 day and 28 days are decreased by 0~36.4% and 0~41.3% with the increasing dosages of secondary aluminum ash. As obtained from the microscopic testing results, the secondary aluminum ash can improve the compactness of hydration products. [ABSTRACT FROM AUTHOR]

Secondary aluminum ash (SAA) is a common waste that, without reasonable treatment, results in pollution to the environment. A large amount of CO2 is emitted by human activities every day. If the CO2 cannot be treated in a timely manner, it will accelerate the greenhouse effect and pollute the environment. The CO2 curing on the surface of SAA can reduce excess CO2 emissions while improving the performance of the SAA. The application of CO2-cured SAA can simultaneously consume the emitted CO2 and solidify the SAA. In this article, the effect of CO2-cured secondary aluminum ash on the rheological properties, the initial setting time, the flexural strength (ft), the compressive strength (fcu) of reactive powder concrete (RPC), and the corresponding dry shrinkage rate (DSR) are investigated. Meanwhile, the capillary water absorption, the chloride ion migration coefficient (CMC), and the carbonization depth of RPC are determined. Scanning electron microscope (SEM) and the X-ray diffraction spectrum curves are selected to reveal the mechanism of the macro performance. Results indicate that CO2-cured secondary aluminum ash can increase the fluidity and decrease the plastic viscosity of fresh RPC. The initial setting time is increased by the CO2 curing. CO2-cured secondary aluminum ash can increase the ft and fcu by (0%~26.3% and 0% to 68.7%), respectively. The DSR is increased by adding secondary aluminum ash with an increasing rate of 0% to 91.3%. The capillary water absorption of RPC increases in the form of a linear function. The CMC and the carbonization depth of RPC are decreased by adding the CO2-cured secondary aluminum ash with decreasing rates of 0%~46.7% and 0%~45.7%. The CO2-cured secondary aluminum ash can make the hydration more compact and increased increase the hydration products (Ca(OH)2). [ABSTRACT FROM AUTHOR]

AlFuMoF was obtained by purifying the secondary aluminum ash and using hydrothermal method and modification treatment. Next, using the β-Cyclodextrin impregnation treatment AlFuMoF, a modified MOF (β-CD@AlFuMoF) was obtained. Both MOFs were subsequently characterized, and their potential for adsorption of fluoride from wastewater was compared. The characterization was performed by SEM, EDS, FTIR, XRD, particle size change and thermogravimetric. The adsorption characteristics of AlFuMoF and β-CD@AlFuMoF under different conditions of pH, contact time as well as initial concentration were evaluated using kinetic and thermodynamic studies and adsorption isotherms. In terms of dynamics, the pseudo second order model fits the experimental data best. According to the Langmuir model, the maximum fluoride adsorption capacity of AlFuMoF and β-CD@AlFuMoF are 22.56 and 39.95 mg g−1, respectively. Thermodynamic studies show that the adsorption of fluoride on AlFuMoF and β-CD@AlFuMoF are spontaneous and mainly controlled by chemical adsorption. According to the findings, β-CD modification of AlFuMoF can be considered as a promising method for removing fluoride from wastewater.

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As a kind of hazardous solid waste, the resource utilization of secondary aluminum ash (SAA) has become a worldwide challenge. The powdered Al and AlN contained in SAA will release a significant amount of heat during thermal treatment, making SAA have the potential to be used as a secondary energy resource. The thermogravimetric analysis (TG/DTG) coupled to a Fourier transform infrared spectrometer (FTIR) was carried out to evaluate the thermal degradation behavior and thermodynamic of SAA from room temperature to 1300 °C at three different heating rates (5, 10, 20 °C/min). The activation energy was calculated by model-free methods, showing that the activation energy of SAA during pyrolysis ranged from 39.99 to 552.3 kJ/mol for conversion rate (α) = 0.1–0.4. The FTIR results displayed gas products including O–H, C–H, N–H, and N=O groups. The increase in temperature from 1100 °C to 1500 °C will make the phase intensity of chloride and AlN gradually decrease, while the Al2O3 is opposite. However, submicron-sized aggregates can still be observed in the sintered samples at 1100 °C and 1200 °C. After calcination at 1500 °C for 3 h, the micro morphology of SAA is basically dominated by large granular Al2O3 and spinel, which verifies the possibility of slag as the raw material for ceramics and refractories. This research provides a novel idea of employing SAA as a secondary energy resource as well as the theoretical basis data on thermodynamics.

Powder sintering and in–situ foaming are the primary treatments for the preparation of glass ceramic foams from solid wastes. However, variables such as crystallization and viscosity, which are difficult to regulate at high temperatures. Herein, a novel technology based on alkali activation–crystallization strengthening was developed for the fabrication of glass ceramic foams with hierarchical pores. Vitrified municipal solid waste incineration (MSWI) ashes as the main calcium and aluminum source and secondary aluminum ash (SAA) as a foaming agent were foamed in NaOH solution at room temperature. The effects of solid–liquid ratio and NaOH concentration on the pore structure, individual foam force, phase evolution and physical properties were investigated, including crystallization kinetics and hierarchical pore formation mechanism. The results indicated that the solid–liquid ratio decreased from 60:40 to 40:60, making the pore wall thin and eventually disappear. The pore size in the range of 0–1 mm reaches 99.5% in 3 mol/L NaOH sample, with the lowest mean size of 0.34 mm. The crystallization kinetics parameters of the basic glass at 5–20 K/min showed that grains were primarily precipitated as three–dimensional at 5 K/min, resulting in micropores. The prepared samples exhibit high porosity (79.23–88.35%), adequate compressive strength (0.36–5.55 MPa) and a bulk density of 0.68–0.76 g/cm3. This work develops the function of SAA as a foaming agent at room temperature, as well as a new idea for the preparation of glass ceramic foams from solid waste containing glass phase or needing vitrification.

To better facilitate the resource utilization of secondary aluminum ash and reduce the consumption of Portland cement, this study investigates the pozzolanic activity grinding fine powder of secondary aluminum ash sintered and ground fine powder (MP) in a Portland cement matrix with different fineness and content. The mechanism of volcanic ash activity was explored using microscopic testing techniques such as XRD, FTIR, TG, SEM, and MIP. The outcomes revealed that as the MP content increased, the fluidity of the cement-based matrix exhibited a declining trend. The addition of MP has a diluting effect on Portland cement, resulting in a decreasing trend of strength activity index with the increase of MP content. Furthermore, under identical content conditions, much finer MP showed a reduction in its pozzolanic activity within the Portland cement-based matrix. Hydration processes and microscopic tests indicated that the addition of the coarser MP particle resulted in higher pozzolanic activity, which is attributed to the faster hydration rate, lower porosity, and higher microstructural compactness. Simultaneously, with an increase in MP content, the porosity and detrimental pore content of the cement-based matrix notably increased, and the content of hydration products reduced. [Display omitted] • The pozzolanic activity of MP in Portland cement matrix was characterized. • The influence of MP on the hydration kinetics of Portland cement was studied. • The pozzolanic activity mechanism of MP in Portland cement matrix was analyzed. [ABSTRACT FROM AUTHOR]

Secondary aluminum ash (SAA) is a type of common solid waste which leads to pollution without treatment. Due to its chemical reactivity, the application of SAA to reactive powder concrete (RPC) may help solidify this solid waste while increasing its performance. However, RPC is usually in active service when used with steel bars. NaCl can corrode the steel bars when reinforced RPC is used in a coastal environment. In this study, the corrosion resistance of reinforced RPC was investigated. The specimens were exposed to an environment of NaCl with freeze–thaw cycles (F-Cs) and dry–wet alternations (D-As). The corresponding mass loss rates (MRs), the electrochemical impedance spectroscopy (EIS) curves and the dynamic modulus of elasticity (DME) were measured. The results show that the MR and the DME of reinforced RPC decrease with increasing values of F-C and D-A. F-C and D-A increases lead to increased electrical resistance (R). The real part value corresponding to the extreme point of the EIS curve is increased by 0~213.7% when the SAA is added. The relationship between the imaginary part and the real part of the EIS fits the quadratic function. The equivalent circuit of the reinforced RPC is obtained from the EIS curves. The R of the rust is calculated by using the equivalent circuit. The rust’s R decreases in the quadratic function with the mass ratio of the SAA. After 200 NaCl F-Cs, the MR, the DME and the R vary within the ranges of 23.4~113.6%, −2.93~−4.76% and 4.92~13.55%. When 20 NaCl D-As are finished, the MR, the DME and the R vary within the ranges of 34.7~202.8%, −13.21~−14.93% and 120.48~486.39%. The corrosion area rates are 2.3~68.7% and 28.7~125.6% higher after exposure to 200 NaCl F-Cs and 20 NaCl D-As. When the SAA is mixed, the MR is decreased by 0~13.12%, the DME increases by 0~3.11%, the R of the reinforced RPC increases by 26.01~152.43% and the corrosion area rates are decreased by 21.39~58.62%. This study will provide a novel method for solidifying SAA while improving the chlorine salt resistance of RPC.

Due to the high moisture, strong hydrophilicity, and hard compressibility of sewage sludge (SS), it is difficult to realize the high-efficiency drying. Herein, a novel SS drying technology was developed to quickly and deeply reduce the moisture of SS from 75.6% to 38.5% in 1 h. During the process, secondary aluminum ash (SAA), a solid waste, was added to SS and acted as skeletons to form plenty of channels. Subsequently, NaOH was added and reacted with SAA to produce a lot of heat, resulting in a rapid temperature rise of the system from 20 to 105°C in 60 s. The heat could effectively remove water from these channels, which could be proved by the T 1 -T 2 maps of in-site Low-Field 1 H nuclear magnetic resonance. In addition, the extracellular polymeric substances were decomposed by SAA/NaOH successfully, and thus the SS became hydrophobic, favoring the drying. Finally, the dried SS could be used to fabricate unburned bricks. Thus, this work provides a promising method to realize the rapid SS deep drying and high-efficiency utilization of SAA and dried SS., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Secondary aluminum ash is a kind of common solid waste which will pollute the environment without any treatment. In this study, the influence of secondary aluminum ash on the rheological properties and the initial setting time of fresh reactive powder concrete (RPC) are researched. Meanwhile, the mechanical properties and the drying shrinkage rates of RPC with the secondary aluminum ash are determined. The electrical parameters of RPC with the secondary aluminum ash are measured. Scanning electron microscopy is obtained to reflect the internal structure of RPC. Results show that the addition of secondary aluminum ash can lead to decreasing the fluidity and increase the yield shear stress of fresh RPC paste by varying rates of 16.1% and 58.3%, respectively. The addition of secondary aluminum ash can decrease the flexural and compressive strengths of RPC cured for 1 day by the decreasing rates of 0~18.7% and 0~19.3%. When the curing age is 28 days, the flexural and compressive strengths of RPC are increased by 0~9.1% and 0~19.1% with adding the secondary aluminum ash. The secondary aluminum ash can promote the condensation of RPC. The addition of the secondary aluminum ash can decrease the electrical resistance of RPC by an order of magnitude. The relationship between the electrical resistance and the electrical reactance fits the quadratic function equation. The electrical resistance of the pore solution increases in the form of a quadratic function with the mass ratio of the secondary aluminum ash. The dry shrinkage rates of RPC cured for 1 day and 28 days are decreased by 0~36.4% and 0~41.3% with the increasing dosages of secondary aluminum ash. As obtained from the microscopic testing results, the secondary aluminum ash can improve the compactness of hydration products.

Aiming at the problem of poor leaching of aluminum and its compounds caused by aluminum nitride in secondary aluminum ash, the secondary aluminum ash was treated via calcification roasting. The focus is on studing the influence of mass ratio, roasting temperature and roasting time on the nitrogen removal rate. The results showed that calcification roasting could quickly reduce the aluminum nitride content in the aluminum ash. The calcification roasting could transform aluminum nitride and aluminum oxide that are not conducive to leaching into 12CaO * 7A12 0$ which is easy to leaching. The optimal process parameters for nitrogen removal treatment of secondary aluminum ash by calcification roasting were also obtained simultaneously. When the mass ratio of calcium oxide to aluminum ash was 0.4, roasting temperature was 900 °C and roasting time was 300 min, the nitrogen removal rate of secondary aluminum ash was 85, 25%, The results provided a reference for the calcification roasting method to improve the leaching rate of aluminum and its compounds in secondary aluminum ash. [ABSTRACT FROM AUTHOR]

A novel lightweight foamed cement-based electromagnetic wave (EMW) absorbing material (Density<0.5 g/cm3) is prepared using secondary aluminum ash (SAA) as a foaming agent and carbon black (CB) as an efficient EMW absorbent, providing a new way to recycle SAA. The pore structure parameters, reflection loss (RL), mechanical strength and thermal conductivity are systematically investigated. The experimental test results indicate that the pore structure of cement matrix prepared by SAA exhibits better EMW loss performance than those prepared by traditional foaming agent. The analysis of the pore structure images indicates that the average pore size is reduced, and pore size distribution shifts towards smaller sizes due to the addition of CB. Furthermore, the roundness of pores is increased due to the formation of more irregular pores. Increasing CB content and thickness can reduce RL, enhance absorbing performance at low frequencies, and broaden effective absorbing bandwidth (EAB). The absorbing performance was tested using the arch reflection method in the frequency range of 1.1–18 GHz, the excellent absorbing performance and the widest EAB (RL<−10 dB) reach −36.34 dB and 14.46 GHz, respectively, at a thickness of 4 cm. Benefiting from excellent pore structure, the foamed cement-based material also exhibits better mechanical strength, and good thermal insulation properties are maintained after adding CB. The compressive and flexural strength can reach 2.18 MPa and 1.02 MPa, respectively, while the thermal conductivity remains below 0.122 W/(m·K). • Lightweight cement-based absorber was firstly prepared using SAA as foaming agent. • The effect of CB on pore structure and EMW absorbing property is investigated. • EAB and minimum RL of the developed absorber reach 14.46 GHz and − 36.34 dB. • A new way to recycle SAA is provided. [ABSTRACT FROM AUTHOR]