Assisted agromining: a nature-based solution to reuse iron mining tailing

Abstract

The economic exploitation of iron mining tailings is an alternative to their disposal in dams, which are structures that are at risk of rupture. Phytomining, a green technology based on the accumulation of the metal of interest in the biomass of a plant to produce bio-ore, can be a strategy. The species Typha domingensis ("cattail") is widely known for accumulating several metals, being a potential accumulator of iron from mining tailings. Therefore, the present work has the following objectives: (i) To determine the total Fe contents in the mining tailings before and after the treatments used, aiming at calculating the efficiency of Fe removal by the plants in each protocol applied; (ii) Evaluate the effects of applied treatments on Fe biogeochemistry in mining tailings through geochemical fractionation and solid phase Fe speciation, as well as evaluate the mineralogical changes promoted by treatments in iron mining tailings through ray diffraction -X; (iii) Evaluate the effect of treatments on the development of Typha domingensis through the determination of plant parameters (height, number of plants and production of dry biomass); and (iv) To determine the total Fe contents in the iron plates, roots and shoots of the macrophyte Typha domingensis. Calculate translocation and bioaccumulation factors under different assisted agromining protocols. The experiment will be conducted for 120 days, with seven treatments (three replications each) distributed in randomized blocks. The effects of the addition of a consortium of beneficial microorganisms (Fe-reducing bacteria), chelating agent (citric acid) and fertilizer (monoammonium phosphate) on the concentration of Fe in the bio-ore will be evaluated. Therefore, the accumulation of iron by the species T. domingensis will be tested in different phytomining protocols, being a promising alternative for disposal of Fe mining tailings with economic exploitation of the material.