A STUDY OF THE PARTIAL NEUTRALIZATION PROCESS OF SOLUTIONS OBTAINED DURING AUTOCLAVE DISSOLUTION OF PYRITE CONCENTRATE.

The process of the partial neutralization of solutions with high concentration of ferric ions and acidity (> 60g l^-1 Fe³⁺ and H₂SO₄), obtained during autoclave dissolution of pyrite concentrate, has been studied. Two types of neutralizers have been used: limestone from deposit ore "Velikan" and a waste from cutting of marble plates - a fine and a coarse fraction. It was found that for the neutralization process limestone and the fine fraction from marble's waste can be used successfully. Both reactants are with a high content of calcium carbonate (> 92 %). The use of the coarse fraction of marble was inappropriate, due to the high content of magnesium carbonate (33.51 %) and the low extraction of gypsum (~ 49 %). The optimal parameters of neutralization process have been established: pH from 0.9 to 1.1, temperature 323K and time of neutralization 60 min. Gypsum, obtained under these conditions, has a high purity (< 0.05 % Fe, < 0.002 % Cu) and a high chemical activity. This makes it a suitable reactant for the conversion to ammonium sulfate, a commercial product that can be used as an artificial fertilizer. [ABSTRACT FROM AUTHOR]