The viscosity, melting proprieties, and molten structure of the high-Al silicon–manganese slag of SiO2–CaO–25 mass% Al2O3–MgO–MnO–K2O system with a varying MgO and K2O content were studied. The results show that with the increase in MgO content from 4 to 10 mass%, the measured viscosity and flow activation energy decreases, but K2O has an effect on increasing those of slags. However, the melting temperature increases due to the formation of high-melting-point phase spinel. Meanwhile, Fourier transform infrared (FTIR) and X-ray photoelectron spectra (XPS) were conducted to understand the variation of slag structure. The O2− dissociates from MgO can interact with the O0 within Si–O or Al–O network structures, corresponding to the decrease in the trough depth of [SiO4] tetrahedral and [AlO4] tetrahedral. However, when K2O is added into the molten slag, the K+ can accelerate the formation of [AlO4] tetrahedra, resulting in the increase in O0 and O− and the polymerization of the structure.

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The effects and reduction mechanisms of carbothermic reduction of vanadium–titanium–magnetite were studied by adding various mass fractions of CaF2 ranging from 0%, 1%, 3%, 5% to 7%. The results showed that the proper CaF2 addition could strengthen the carbothermic reduction of vanadium–titanium–magnetite while the excessive amounts will weaken the promotive effect, hence the appropriate dosage was determined to be 3 mass%. The CaF2 was favorable for the carbon gasification reaction, where it increased the partial pressure of CO inside briquette and caused the lattice distortion of vanadium–titanium–magnetite. The reaction improved the reduction process and accelerated the reduction rate. The appearance of 3CaO·2SiO2·CaF2 and other complex compounds with low melting point facilitated the aggregation and growth of the slag and the iron, which increased the concentration of iron grains and the aggregation level of the slag.

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The method of continuous treatment with Na 2 CO 3 solution, HF solution, and CO 2 was proposed for the regeneration of the exhausted activated carbon (EAC) produced in the sintering flue gas purification process. In order to obtain the optimal operation conditions, the effect of key parameters such as Na 2 CO 3 solution concentration, HF solution concentration, and CO 2 activation temperature on the sulfur conversion rate and regeneration efficiency was analyzed. Also, the N 2 adsorption, Brunauer−Emmett−Teller analysis, scanning electron microscopy-energy dispersive spectrometry, X-ray diffraction, X-ray fluorescence, and Fourier transform infrared spectroscopy were adopted to investigate the deactivation reason and the change of the physical−chemical properties. The results showed that the deactivated EAC was mainly due to the deposition of inorganic compounds such as CaSO 4 , SiO 2 , and KCl to block the pores. Continuous treatment with Na 2 CO 3 solution and HF solution could remove the inorganic compounds effectively. CO 2 activation treatment further developed the blocked porosity and decreased the surface acidity. The optimal conditions for the regeneration of EAC were a Na 2 CO 3 concentration of 0.5 mol/L, an HF concentration of 0.8 mol/L, and a CO 2 activation temperature of 1073 K with the activation time of 1 h, corresponding to the specific surface area of 607.91m 2 /g. In the fourth regeneration cycle, the adsorption performance during the successive adsorption− regeneration process could still maintain a high level and the regeneration efficiency was 95.31%.