Preparation process for high-purity alpha-Fe2O3 by ferrous sulfate-ammonium carbonate method

The invention discloses a manufacturing technique of high-purity alpha-Fe2O3 through ferrous sulfate-ammonium carbonate method, which comprises the following steps: 1. putting FeSO4íñ7H2O into dissolving groove; adding excessive ferric chip and hot water and chemical purifier; adjusting pH value between 4 and 5; stirring; making 460+-10g/L solution with FeSO4 under 60-70 deg.c; insulating; stewing; rectifying; pumping chemical purified liquid into ion exchange purifying groove; analyzing the content of harmful component; proceeding ionic exchange; adsorbing to remove residual impurity ion; obtaining high-purity FeSO4 liquid; 2. adding ammonium hydrogen carbonate, ammonia, warm water and purifier into dissolving groove of ammonia; stirring; dissolving; rectifying; obtaining purifying liquid with 330 +-20g/L (NH4)2CO3 and 20+-5g/L free ammonia under 52+-3 deg.c; 3. pumping two purifying liquid into specific double-circulating decomposing sediment groove according to proportion; obtaining the FeCO3 crystal; rinsing through pure water; drying; putting into stove; aerating hot purified wind not less than 600 deg.c; adding 25% steam to sinter the mass into alpha-Fe2O3; 4. adjusting the pH value of reacting mother liquid to 7; proceeding multi-effect condensing; obtaining (NH4)2SO4 as by-product.