Assessment of the soil utilization potential of vanadium-titanium magnetite tailings based on a chemical, biological, and mineralogical characterization

Vanadium-titanium magnetite tailings are bulk industrial solid wastes and can be found in the Panxi Region of Sichuan province. The utilization of vanadium-titanium magnetite tailings as soil represents a viable strategy for achieving extensive depletion, while simultaneously fostering ecological revitalization. In order to effectively reuse the stockpiled Vanadium-titanium magnetite tailings, a comprehensive analysis was conducted to assess their physicochemical attributes, microbial community composition, and mineralogical makeup.

The morphologies of six heavy metals, V, Cd, Cr, Cu, Ni, and Fe, extracted from different depths of the tailings soil were extracted and analyzed using the modified European Community Bureau of Reference (BCR) sequential extraction procedure. The physicochemical indexes—such as water content, pH, available sulfur, and available potassium, of the tailings soil were analyzed. The microbial community structure was analyzed using high-throughput sequencing, and the mineral composition was analyzed using X-ray diffraction (XRD).

The concentrations of Ni, Cu, Cr and Cd in the vanadium-titanium magnetite tailings are all within the controllable range. The content of available phosphorus was graded as level 1 (> 40 mg/kg), the content of cation exchange capacity (CEC) was graded as level 1 (> 20 cmol ( +)/kg), and the content of available sulfur was 6.91 times higher than the average value (34.3 mg/kg) of available sulfur of the 10 southern provinces of China. At the T3-D3 sample sites, the Geothermobacter genus prevailed, while Thiobacillus reigned supreme at the remaining sampling locations. The microbial populations in the tailings were primarily influenced by sulfur and iron metabolism. The X-ray diffraction (XRD) analyses showed that pyroxene, mica, cordierite, and kaolinite were the primary minerals in the tailings.

There is a low risk of soil contamination from the utilization of vanadium and titanium magnetite tailings as an ecological reclamation substrate. Organic matter and nitrogen being the limiting indicators of soil utilization. The abundance of Actinobacteria and Bacteroidota can be appropriately intensified during soil utilization to enhance the soil nitrogen and carbon cycling performance. The chemical weathering dominated the tailings, and its maturation could be accelerated by strengthening the chemical weathering pathway of tailings.