In this paper, the effects of CaO on the phase evolution mechanism of vanadium slag during slagging, direct roasting, and (NH₄)₂CO₃ leaching processes are investigated. Results indicate that with the increase in CaO content, vanadium is always concentrated as (Fe, Mn, Mg)V₂O₄ in spinels, part of titanium is concentrated and transformed into CaTiO₃, and phosphorus is concentrated in 3CaO·P₂O₅ (C₃P) and transformed into n·2CaO·SiO₂-3CaO·P₂O₅ (nC₂S-C₃P). During the direct roasting process, a part of the vanadium-containing spinel phase oxidizes and reacts with Ca₂SiO₄ to produce calcium vanadate (Ca₃V₂O₈, Ca₁₀V₆O₂₅, and Ca₂V₂O₇), which is soluble in (NH₄)₂CO₃ aqueous solution. However, a part of the vanadium-containing spinel phase is oxidized and decomposed to vanadium oxides (V₂O₅ and V₆O₁₃), which are insoluble in (NH₄)₂CO₃ aqueous solution. This is not beneficial for vanadium extraction using (NH₄)₂CO₃ aqueous solution. In addition, (NH₄)₂CO₃ aqueous solution can restrain the leaching of C₃P from the nC₂S-C₃P solid solution in the directly roasted vanadium slag with high CaO content.

In recent years, the widespread application of Mg alloy casting and Mg alloy products has generated a large amount of Mg alloy waste. This experiment used a single factor experimental analysis method to study the optimal process for removing Fe from Mg alloy AM50A waste, and developed an efficient Fe removal and regeneration process for Mg alloy AM50A. It was found that the optimal refining temperature for removing Fe ions was 670 °C, the optimal refining (RJ-2) agent mass ratio was 1.5%, and the optimal refining time was 40 min. Regenerated J40-1.5-AM50A Mg alloy was prepared using the best refining process, and its composition and mechanical properties were tested and analyzed. The experimental results show that the composition of the regenerated J40-1.5-AM50A Mg alloy prepared by this method is consistent with AM50A, with an Fe removal rate of 96.2%. The mechanical properties were improved compared to the original AM50A sample, with a maximum tensile strength increase of 1.611 KN and a tensile strength increase of 26.333 MPa. The elongation after fracture is 2.25 times that of the original sample. Research has shown that the RJ-2 refining agent can provide mechanical properties of magnesium alloys during the refining process. By analyzing the composition, XRD, SEM, and EDS of AM50A (Fe) and J40-1.5-AM50A, it was found that the refining process accelerates the removal of Fe in the form of Fe deposition.

Against the backdrop of continuously expanding global magnesium alloy applications and surging scrap generation, achieving efficient recycling and low-carbon regeneration of magnesium alloys has emerged as a key pathway for advancing green transformation in manufacturing. The AM50A recycled magnesium alloy was selected as the research subject, employing the attributional life cycle assessment (ALCA) methodology to systematically calculate its “cradle”-to-“gate” carbon footprint across three stages: raw material acquisition, transportation, and production. The results indicate that the carbon footprint of AM50A recycled magnesium alloy is 4.9399 kg CO₂e/kg, with the production stage accounting for a significant 99.34% of emissions, identified as the primary source. The combined contribution from raw material acquisition and transportation stages is only 0.66%. Compared to magnesium alloys produced by the Pidgeon process, greenhouse gas (GHG) emissions can be reduced by approximately 67.56% through the recycling process, highlighting its significant advantages in promoting low-carbon manufacturing and circular economic development for magnesium alloys. This study provides data support for the environmental performance assessment of recycled magnesium alloys and offers a scientific basis for optimizing energy conservation and emission reduction pathways in related industries.