Estudo sobre a solubilidade de fosfatos em ácido cítrico a 2%

Abstract

The solubility of several phosphatic fertilizers, namely, ''Hiperfsfato", Florida rock phosphate, Olinda rock phosphate, Alvorada rock phosphate, Araxá apatite, and fused magnesium phosphate (Termofosfato) was studied by using varying proportion of 2 per cent citric acid: 1:100, 1:200, 1:300, 1:400, 1:500, 1:750 and 1:1000. The fused phosphate showed the highest solubility for all conditions of extraction. Hiperfosfato followed closely fused phosphate beginning at the 1:400 ratio of extractions. Alvorada rock phosphate and Araxa apatite showed the lowest degree of solubility among all the products studied, giving almost identical results. Both Florida and Olinda rock phosphate, showed an intermediate rate of solubility. Starting from the ratio 1:100 fused phosphate shows an almost total solubility; the same is true for Hiperfosfato from the ratio 1:400 and up; total solubility of Florida and Olinda rock phosphates were achieved only at the high ratio of 1:1000; solubility of Alvorada rock phosphate and Araxa apatite was much lower. It is worth mentioning, however, that Alvorada rock phosphate at narrow rations up to 1:300 showed a higher degree of solubility than Olinda and Florida rock phosphates.