Mineralogical analysis of rock dust for remineralization of soil intended for pasture

Abstract

The objective of this study was to verify the effects of rock dust on the soil of an area destined for pasture. Mineralogical analysis of the rock dust was performed using X-ray diffraction, and the major oxides and minor elements were analyzed using X-ray fluorescence. The soil samples were analyzed according to PROFERT-MG. The following were identified from the X-ray diffractogram of the total rock powder: quartz (43.66%), albite (38.10%), microcline (15.30%), and muscovite (1.80%). Regarding the major elements, SiO2 (81.92%), Al2O3 (11.04%), and Na2O (3.86%) were predominant, and an important amount of K2O (2.61%) was present. In the chemical characterization of the soil, an increase in the levels of P, K, Ca, Mg, Sb, t, V, organic matter, and organic carbon were observed with the addition of rock dust. A comparison of the chemical analysis results with the CONAMA quality reference values indicated that the rock dust sample had acceptable levels with respect to the quality reference for all analyzed heavy metals. In a comparative analysis with MAPA's Normative Instruction No. 5/2016, it was found that rock dust does not fully comply with the minimum requirements of the legislation. In full compliance with the IN from chemical analysis, it had a minimum required content of at least 1% for K2O. Preliminary studies have indicated that the application of this material as a remineralizer has potential, mainly in relation to the supply of K2O. However, physical adjustments are required in the beneficiation process to comply with the standards.