GLAUCONITA COMO FONTE ALTERNATIVA DE POTÁSSIO PARA PRODUÇÃO DE FERTILIZANTE DE LIBERAÇÃO LENTA

Abstract

Glauconite (K₂(MgFe)₂Al₆(Si₄O₁₀)₃(OH)₁₂) is a monoclinic mineral, greenish, phyllosilicate hydrated of potassium and iron. It is an alternative source of potassium. This work investigated the dissolution of potassium in a solution of 2wt% citric acid after previous thermal and chemical processing with additives (CaCO₃, MgCl₂.6H₂O) of glauconita-bearing rock at six temperatures: 660°C, 700°C, 740°C, 780°C, 820°C and 860°C, 60 minutes and particle size less than 0.15mm. The mass ratio rock:CaCO₃:MgCl₂.6H₂O was: 1.0:0.2:0.3. For this purpose, a rock containing glauconite from the Cedro do Abaeté - MG, with 11.9% of K₂O and (58% of glauconita) was selected. The evaluation of potassium extraction was by carried out in citric acid 2wt% solution at 95°C for 15 minutes. The highest extraction of potassium (K) was 78% at the temperature of 770°C. The curve of extraction goes through a maximum (770°C), showing that there is a limit to the temperature in the thermal processing. Above this value there is a drop in the extraction indicating different mechanisms of reaction between the rock and additives. Considering the range up to 770°C, thermal processing makes Verdete ore a potential alternative source of potassium for the production of long-term fertilizer.

Keywords: Potassium; Verdete; Thermal Processing; Glauconite.