Kinetics of Potassium Release From Silicate Rock Residues: Influence of Extracting Solutions and Particle Size

Abstract Purpose Kinetic considerations are important for determining the long-term stability of many minerals in soils. The objective of this work was to evaluate the kinetics of K solubilization contained in residues from silicate rock mining using different extraction solutions, including deionized water and organic acetic, oxalic, tartaric, and malic acids. Methods Residues of mica schist (RMS), syenite (RSY), granite (RGR), basalt (RB1 and RB2), barren rock from gold mining (RBR) and phonolite rock dust (RPH) were used in two particle size ranges (< 103 and < 300 μm). The tubes containing the samples and extraction solutions were shaken and aliquots were collected at 0, 0.5, 2, 8, 24, and 48 h to determine the K concentration in the solution. Results An initial rapid release of K was observed after approximately 4 h, with subsequent stabilization in most cases. RMS and RPH were the most reactive materials in the smallest particle-size range. An association was found between the values of K soluble in acetic acid and the concentrations of phyllosilicates, whereas the concentrations of K soluble in oxalic, tartaric, and malic acids showed an intermediate association with the concentrations of tectosilicates and phyllosilicates present in the samples. Conclusion The observed low solubility indicates limited short-term potassium availability from these materials under experimental conditions.