Análise da qualidade do calcário na região sudoeste do Mato Grosso do Sul

Abstract

Mato Grosso do Sul is responsible for a large amount of limestone extraction produced in Brazil, even though it buys many tons from other regions, specifically from Paraná. The consumption of limestone in the Central-west region of Brazil is due to the fact that the soil is acidic, has a low content of calcium (Ca) and magnesium (Mg) and a high content of toxic elements. Therefore, liming is a means of making calcium and magnesium available to the soil, neutralizing acids. Calcareous samples from the region were collected in order to evaluate the quality of limestone extracted in the state. Four samples from different mines were analyzed chemically and physically according to the legislation. The limestone samples analyzed by TG-DSC technique presented a single characteristic mass loss which can be attributed to the thermal decomposition of calcium carbonate (CaCO3) with liberation of carbon dioxide (CO2) at 800 ° C. This decomposition led to formation of a single residue, calcium oxide (CaO), as final residue. From this technique it was not possible to detect the presence of magnesium, so that the limestones studied can be classified as calcitic. From the residue (CaO), the percentage of neutralization power (PN) was also calculated by summing the percentages of oxides produced by the samples. From granulometric analysis, the reactivity (RE) and the relative total neutralization power (PRNT) were determined. In summary, these analyzes are in accordance with the recommendations of the Ministry of Agriculture, Livestock and Food Supply regarding limestone quality in terms of its gauged chemical and granulometric composition, minimum characteristics established for soil acidity correctives. Another relevant analysis performed in this work was the relative total neutralization power (PRNT) measured in percentage, by which it was possible to determine that the studied samples are classified within two bands, B and C (60 - 90%), i.e.suitably corrective to commercialization and in compliance with the current legislation.