Increasing Soluble Phosphate Species by Treatment of Phosphate Rocks with Acidic Waste
2016
Santos, Wedisson O. | Hesterberg, Dean | Mattiello, Edson M. | Vergütz, Leonardus | Barreto, Matheus S. C. | Silva, Ivo R. | Souza Filho, Luiz F. S.
The development of efficient fertilizers with a diminished environmental footprint will help meet the increasing demand for food and nutrients by a growing global population. Our objective was to evaluate whether an acidic mine waste (AMW) could be used beneficially by reacting it with sparingly soluble phosphate rocks (PRs) to produce more soluble P fertilizer materials. Three PRs from Brazil and Peru were reacted with different concentrations of AMW. Changes in mineralogy and P species were determined using a combination of X‐ray diffraction and phosphorus K‐edge XANES spectroscopy, in addition to extractable P concentrations. Increasing the AMW concentration typically increased extractable P. X‐ray diffraction data showed transformation of apatite to other species when PRs were reacted with AMW at ≥50% (v/v) in water, with gypsum or anhydrite forming at AMW concentrations as low as 12.5%. Linear combination fitting analysis of X‐ray absorption near edge structure spectra also indicated a progressive transformation of apatite to noncrystalline Fe(III)‐phosphate and more soluble Ca‐phosphates with increasing AMW concentration. Because this AMW is costly to dispose of, reacting it with PR to produce a higher‐grade phosphate fertilizer material could decrease the environmental impacts of the AMW and diminish the consumption of pure acids in conventional P fertilizer production. CORE IDEAS: Reusing fertilizer production waste can lower its environmental impact and enhance crop production. We evaluated products of acid mining waste reacted with phosphate rocks. Chemical speciation analyses indicated conversion of apatite to more soluble phosphates. New P products have agronomic potential. Plant growth tests are needed to measure these P products’ performance as fertilizers.
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