Extractant efficiency in the solubilization of alternative sources of potassium

Eficiência de extratores na solubilização de fontes alternativas de potássio

ABSTRACT.

Knowledge of a rock's composition allows for inferences regarding several properties, ranging from its physical characteristics to its solubility. This study aimed to evaluate the use of different extractants to solubilize the K present in rocks as a potential source of nutrients and the effects of extractant contact time and temperature on rock solubilization. Samples of two rocks and a mineral concentrated from a granitic rock were treated with ammonium dihydrogen phosphate (NH₄(H₂PO₄)), calcium dihydrogen phosphate (Ca(H₂PO₄)₂), sodium hydroxide (NaOH) and water (control). Sample-extractant treatments were performed using a water bath shaker at temperatures of 25 and 50°C for periods of 3, 7, 10, 20, and 30 days. The amounts of K extracted from rocks using the extractants were in the following order: NH₄H₂PO₄>Ca(HPO₄)₂>NaOH>water. The sequence of K release (ppm) based on the rocks studied was as follows: nepheline syenite>green banded argillite>concentrated biotite. Increasing the extractant contact time and temperature enhanced the solubilized K content.

Keywords:
minerals; soluble K; fertilizers; powdered rock.