Brazilian Bauxite Residue Physical-Chemical Characterization and Acidic Neutralization Potential

摘要

Physical-chemical evaluation of Brazilian (Amazon region) bauxite residue (BR) and analysis of its acid neutralization capacity (ANC) using, hydrochloric (HCl), sulfuric acid (H_2SO_4) and citric acid (C_3H_8O_7) were carried out to assess the potential application of BR as soil ameliorant. Analysis indicated a particle size average size (D_(50)) of 6.04 urn, 1.65 g cm~(-3) density and 18.28 mS cm~(-1) electrical conductivity. Mineral phases determined by XRD showed hematite, aluminous goethite, anatase, sodalite, gibbsite and quartz, in agreement with XRF (%) elemental characterization: Fe (24.38), Al (11.20), Si (7.91), Na (8.11), Ti (3.24), Ca (0.79), Zr (0.71), S (0.06), V (0.07) and Mn (0.09). ANC analyses conducted after 21 days indicated a lower acid consumption and pH equilibrium for H_2SO_4 and HCl (1.75 and 1.00 mol H+ kg-1, respectively and ~pH8) when comparing with C_3H_8O_7 (2 mol H~+ kg~(-1)). Results validate and provide basis for an effective use of BR in agronomic applications.