Activation of Iron Tailings with Organic Acids: A Sustainable Approach for Soil Amelioration

The large-scale accumulation of iron tailings poses serious environmental challenges and represents a significant loss of potential resources. Due to the stable silicate mineral structure of iron tailings, essential nutrient elements remain encapsulated, resulting in low bioavailability and limited uptake by plants. This characteristic greatly restricts their direct use in agricultural applications. To overcome this limitation, this study employed three organic acids, namely citric acid, oxalic acid, and acetic acid, to activate iron tailings. The activation efficiency was systematically evaluated, and the effects of activated iron tailings on plant growth were assessed through pot experiments. The results showed that all three organic acids significantly enhanced the release of available silicon and iron from iron tailings, with oxalic acid exhibiting the highest activation capacity, increasing available Si and Fe to 882.99 mg/kg and 395.41 mg/kg, respectively. Pot experiments further revealed that the organic acid–iron tailing composites markedly improved soil nutrient availability, with available potassium, phosphorus, alkali-hydrolyzable nitrogen, iron, and silicon increasing by 50.03%, 95.99%, 82.59%, 163.21%, and 200.01%, respectively. Consequently, plant growth was substantially enhanced, including increases in plant height (29.49%), shoot fresh weight (41.62%), and shoot dry weight (39.89%). This study provides a novel and sustainable strategy for the valorization of iron tailings as an agricultural resource and soil amendment, demonstrating considerable potential for both environmental remediation and agronomic improvement.