Optimizing the dewatering performance of zinc smelting iron Slag: Investigating the influence of ultrasonic Time, ultrasonic Power, and Liquid-Solid ratio using response surface methodology.

Iron slag, a byproduct of the wet zinc refining process, contains a substantial amount of valuable metals such as iron and zinc, making it highly valuable for comprehensive recovery and reuse. However, before recovery, the iron slag requires dehydration pretreatment. The water content in iron slag remains relatively high and difficult to remove even after pressure filtration, leading to extended drying times, reduced drying efficiency, and increased energy consumption. This study explores a novel ultrasonic pretreatment process for iron slag. Using the response surface methodology, we investigated the effects of ultrasonic power, ultrasonic time, liquid-to-solid ratio, and their interactions on the water content, capillary suction time (CST), and filtration resistance of the slag. Regression equations were established to predict the relationships between the water content, CST, filtration resistance, and the various factors. The optimal process parameters were determined as an ultrasonic power of 60 W, ultrasonic time of 22 s, and a liquid-to-solid ratio of 4:1. Under these conditions, the dehydration performance of the iron slag was optimal. The measured values closely matched the predicted values, demonstrating the reliability of the model and the feasibility of the optimized process. Our study of the mechanism of ultrasonic action on iron slag found that under the influence of ultrasonic waves, the particle size of the slag significantly decreased, and the particle morphology changed. Compared to conventional drying, the drying rate of the iron slag after ultrasonic pretreatment was accelerated, and the drying time was reduced.

Study on the Drying Kinetics of Zinc Smelting Iron Slag Assisted by Ultrasonic Waves.

This study investigates the impact of ultrasonic treatment on the drying kinetics of zinc smelting iron slag. Through the Arrhenius equation, it was found that the reaction order of zinc smelting iron slag remains constant at 1/2 before and after ultrasonic treatment, indicating a proportional relationship between the reaction rate and the square root of the reactant concentration. Despite the increased drying rate of the iron slag due to ultrasonic pretreatment, the reaction order remains at 1/2. Additionally, it was observed that the drying kinetics of untreated iron slag aligns with the Wang and Singh model, while the drying kinetics of ultrasonically pretreated iron slag fits the Page model. The Page model facilitates the prediction of drying rate and drying time for ultrasonically pretreated iron slag, enabling the optimization of the drying process, enhancing efficiency, and comparing drying performance under different conditions. Using ultrasonic pretreatment, the subsequent drying process of iron slag can significantly shorten the time and save energy. These findings provide essential theoretical foundations for optimizing the drying process of zinc smelting iron slag.

Effect of ultrasonic-induced selenium crystallization behavior during selenium reduction.

In this work, the crystallization process of selenium was accelerated by ultrasonic wave. The effects of ultrasonic waves and conventional conditions of selenium crystallization were compared to understand the effects of different conditions on crystallization, including ultrasonic time, ultrasonic power, reduction temperature, and H2SeO3 concentration. The mechanism of ultrasound affecting selenium crystallization was also investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The experimental results showed that ultrasonic time, ultrasonic power, and reduction temperature significantly influenced the crystallization process and morphology of selenium. Ultrasonic time had a large effect on the completeness (all products have been crystallized) and integrity of the crystallization of the products. Meanwhile, ultrasonic power and reduction temperature had no effect on the completeness of crystallization. However, it had a significant effect on the morphology and integrity of the crystallized products, and different morphologies of the nano-selenium materials could be obtained by changing the ultrasonic parameters. Both primary and secondary nucleation are important in the process of ultrasound-accelerated selenium crystallization. The cavitation effect and mechanical fluctuant effects generated by ultrasound could reduce the crystallization induction time and accelerate the primary nucleation rate. The high-speed micro-jet formed in the rupture of the cavitation bubble generated is the most important reason to influence the secondary nucleation of the system.

Preparation of a Novel Zn(II)-Imidazole Framework as an Efficient and Regenerative Adsorbent for Pb, Hg, and As Ion Removal From Water.

An outstanding metal-organic framework sorbent (Zn-MOF) was prepared using Zn2+ and 3-amino-5-mercapto-1,2,4-triazole to eliminate toxic metal ions from water. Zn-MOF was detected via using Fourier-transform infrared (FTIR) spectroscopy, field-emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller (BET) analysis, and X-ray photoelectron spectroscopy (XPS). Zn-MOF is stable and has a very large surface area. The uptake properties of Zn-MOF were investigated. The maximum uptake capacity of Zn-MOF for Pb, Hg, and As ions was 1097, 32, and 718 mg/g, respectively. This was obtained at pH = 4, 5, and 6, respectively. The adsorption data is in good agreement with the Langmuir and pseudo-second-order rate models, indicating that the uptake process of Zn-MOF for toxic metal ions was a single layer uptake on a uniform surface via exchange of valence electrons. Thermodynamics shows that the uptake process is autogenic and endothermic. Zn-MOF can be reused at least 6 times. Mercury and lead strongly coordinated with Zn-MOF. The interaction between arsenic and Zn-MOF is weak chemical coordination and ion exchange. Zn-MOF has wide application prospects for toxic metal ion elimination.

Dielectric Properties of Silicothermic Reduction Chromite in the Microwave Field.

The microwave absorption properties of chromite and the feasibility of microwave reduction chromite have been discussed. The results show that as the density increases, the dielectric properties of materials increase. The dielectric properties are the best (the value around 4.2) when the silica ratio is 0.5. Microwave penetration depth shows that chromite and the mixture have good wave absorption properties.