The Alkaline Fusion-Hydrothermal Synthesis of Blast Furnace Slag-Based Zeolite (BFSZ): Effect of Crystallization Time

Blast furnace slag (BFS) is usually regarded as a by-product of the steel industry, which can be utilized as raw material for preparing BFS-based zeolite (BFSZ). In this study, BFSZ was successfully prepared from BFS using alkaline fusion-hydrothermal synthesis. Via the analyses by XRD, SEM, EDX, XRF, FT-IR, elemental mapping and BET/BJH methods, BFSZ crystallization was almost complete at 6 h. With a further increase of crystallization time to 8 h, no significant effect on the formation of crystalline phase was found. Meanwhile, the zeolite content Si/Al (Na/Al) molar ratio was highly affected by crystallization time. The main component of BFSZ prepared at 6 h is cubic crystal with developed surface, with particle size around 2 μm. Moreover, further increasing the crystallization time will not significantly influence the size and morphology of BFSZ product.

Comparative Studies of Digestion Techniques for the Dissolution of Neodymium-Based Magnets

The digestion of neodymium (NdFeB) magnets was investigated in the context of recycling rare earth elements (i.e., Nd, Pr, Dy, and Tb). Among more conventional digestion techniques (microwave digestion, open vessel digestion, and alkaline fusion), focused infrared digestion (FID) was tested as a possible approach to rapidly and efficiently solubilize NdFeB magnets. FID parameters were initially optimized with unmagnetized magnet powder and subsequently used on magnet pieces, demonstrating that the demagnetization and grinding steps are optional.

Re–Os dating of molybdenite via improved alkaline fusion

This study describes an improved alkaline fusion technique for the Re–Os dating of molybdenite.

Optimization of Parameters and Methodology for the Synthesis of LTA-Type Zeolite Using Light Coal Ash

The synthesis of zeolites using waste as a source of Si and Al is well known, and light coal ash has been studied to minimize the problems of waste management and mitigate environmental effects. The residue used in this work was supplied by Coal Workers Assistance Society (SATC) Criciúma–SC/Brazil, and had 24.09% Al2O3 and 54.25% SiO2 in its chemical composition. Synthesis studies using this residue with the objective of obtaining LTA zeolites were carried out by hydrothermal means, alkaline fusion, and the combination of the two methods, varying parameters such as crystallization time, Na/T ratio, OH/ratio, ultrasound exposure, gel agitation temperature, and the alkaline melting temperature of the residue. The results were characterized by X-ray diffraction (XRD) techniques and scanning electron microscopy (SEM-FEG). It was possible to obtain 70% crystalline zeolite type LTA for the first time at mild conditions with temperatures below 200 °C by alkaline fusion with smaller amounts of NaOH and short times (2 h). Thus, suitable parameters were determined for future scaling.