Revisiting Limestone Quality for Soil Liming Purpose

Abstract

The quality of lime is generally estimated by traditional methodologies, which consist of coarse granulometry and chemical reactivity determinations. Performing a detailed chemical/mineralogical and fine granulometric characterization is the objective of this study. Fifteen lime samples, from an original 52 commercial samples, were analyzed by their granulometric profile (GP) and chemical-mineralogical compositions to discuss limestone quality inside the tree group of traditional efficiency neutralizing power (ENP) and Mg contents. The lime reactivity was estimated using laser diffraction under water and acid solution (1 mol L−1 HCl). The grain-size distribution ranged from 0.563 to 1124 µm and the GP was associated with the chemical and mineralogical compositions. Samples with high ENP (>99%) presented differences in GP regarding Mg contents. Lime with low ENP presents the most varied mineral assemblage, while calcite and dolomite were the predominant minerals in high-ENP samples. Samples containing high Mg were the most sensitive to the acid solution, suggesting great reactivity. This work contributes to a better understanding of limestone quality than routine analyses performed so far. Additionally, the use of the laser diffraction method promotes a rapid lime reactivity test for liming purposes.