TRANSFORMATION OF MONOCALCIC PHOSPHATE IN BICALCIC PHOSPHATE

Abstract

The state of Goiás is rich in monocalcic phosphate, which is used as fertilizer and has low price, in order to change it to bicalcic phosphate, which has high price and is used for cattle feeding. A new technique of bicalcic obtention was developed from the monocalcic, and not from the phosphatic rocks or from the calcium oxide reaction with sulphuric acid. The methodology applied was the following: Preparation of the samples trying to obtain them with contents of free acidity varying from one to six in function of sulphuric acid (samples which are called T1, T2......T6 respectively). After obtaining the wished degrees of acidity, the thermic treatment was given, that is, the samples were subjected to temperatures, such as 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 260, 280 and 300 degrees centigrade, in an exposition time of 20, 30 and 40 minutes. At the end, the samples were analyzed in order to dose the contents of soluble P205  in 2% citric acid. Through the analysis of these contents, it was concluded that from the treatments made, the most efficient method to transform the monocalcic phosphate in bicalcic was the 5 treatments with the exposition time of 40 minutes, under the temperature of 280°C.