Agronomic efficiency of phosphate fertilizers produced by the re-use of a metallurgical acid residue

摘要

AbstractThe production of fertilizers with industrial wastes reduces the environmental impacts of waste disposal and improves environmental sustainability by generating added-value products. Our objective with this study was to evaluate the agronomic performance and potential soil/plant contamination with heavy metals of alternative phosphate (P) fertilizers, obtained from the acidulation of phosphate rocks (PR) by a metallurgical acidic waste. Seven P fertilizers were evaluated: three PR (Araxá, Patos, and Bayóvar), their respective acidulated products (PAPR), and triple superphosphate fertilizer (TSP). A greenhouse trial was carried out to test the agronomic performances of fertilizers in a sequentially cultivated maize-soybean-white oat. The reaction of PR with acid waste was effective to increase their solubility and improve plant yield and P uptake compared to their natural PR. There was a cumulative recovery by plants of 1.4 and 8.1% of added P via PR and PAPR, respectively. No increase in heavy metal (Cd, Pb, Cr, and Ni) availability in soil or accumulation in shoots was observed, indicating that the PAPR were environmentally safe. The usage of acid waste to produce P fertilizers therefore represents a strategic way to employ marginal products for the production of fertilizers.Highlights•Phosphate rocks require chemical or thermal treatment to produce high-grade P fertilizers;•Metallurgical acid residue can efficiently be used to produce soluble P fertilizers;•The produced fertilizers are agronomically effective and safe regarding heavy metal concentrations;•The re-use of this acid residue to produce P fertilizers is more environmentally friendly and cheaper compared to traditional processes.