高温におけるFe2(SO4)3溶液の加水分解に及ぼすZnSO4の影響について

Abstract

Hydrolysis of acidic ferric sulphate solutions of various concentrations with the addition of zinc sulphate has been investigated in an autoclave at the temperatures of 185°C and 200°C. The results obtained were as follows;1. When the hydrolysis of ferric sulphate solutions was at equilibrium, the final concentrations of iron in the solutions increased with the increase of sulphuric acid concentrations, but at the same sulphuric acid concentrations, those of iron decreased considerably with the addition of zinc sulphate.2. In the hydrolysis of ferric sulphate solutions, ferric oxide, Fe2O3, was precipitated at lower sulphuric acid concentrations. But the stable region of ferric oxide was extended with the addition of zinc sulphate in the ferric sulphate solutions.3. In the hydrolysis of ferric sulphate. solutions at 185°C in the absence of zinc sulphate, Fe2O3is stable below 55.8g/l H2SO4, and Fe (OH) SO4is stable above 55.8g/l H2SO4. When zinc sulphate was added to the solutions, Fe2O3is stable'over a wide range of conditions. For example, at 185°C, when respectively about 70g/1 Zn and 100g/l Zn as zinc sulphate were added, Fe2O3is stable up to 84.2g/l H2SO4and 93.0g/l H2SO4.4. In the hydrolysis of ferric sulphate solutions at 200°C, in the absence of zinc sulphate, Fe2O3is stable below 69.3g/l H2SO4, and Fe (OH) SO4is stable above 69.3g/l H2SO4. When respectively about 70g/l and 100g/l Zn as zinc sulphate were added, Fe2O3is stable up to 103.8g/l H2SO4and 112.5g/l H2SO4.5. When zinc sulphate was added to the solutions, the relations between the concentrations of iron and those of sulphuric acid over the ferric oxide stable region are expressed _by the following experimental equations. At the temperature of 185°C log [Fe (g/l)] =4.91 log [H2SO4 (g/l)]-8.93 about 70g/l Znas zinc sulphate log [Fe (g/l)] =8.21 log [H2SO4 (g/l)]-15.28 about 100g/l Znas zinc sulphate At the temperature. of 200°C log [Fe (g/l)] =3.82 log [H2SO4 (g/l)]-7.23 about 70g/l Znas zinc sulphate log [Fe (g/l)] =5.46 log [H2SO4 (g/l)]-10.31 about 100g/l Znas zinc sulphate6. The equilibrium diagram of the ternary system Fe2O3-SO3-H2O in the presence of zinc sulphate at 185T, and 200°C were established from the experimental data.