ON THE CATALYSIS OF FERROUS SULFATE OXIDATION IN AUTOCLAVES BY NITRATES AND NITRITES

The effect of small concentrations of nitrate (KNO3, HNO3) and nitrite (NaNO2) on ferrous sulphate oxidation in a sulphuric acid solution un der pressure was investigated. Nitrate did not result in noticeable ac celeration of ferrous ion oxidation, whereas the same concentration of nitrite resulted in significantly catalyzed oxidation. Experimental r esults also suggested that the nitroso-ferrous complex, Fe(NO)(2+), if present, does not adversely affect the reaction rate. In addition, ga s venting did not result in a loss of catalyzing effect, and hence NOx species. These results show that adoption of nitrite-assisted oxidati on in autoclaves used for minerals processing could result in more eff icient operations.