Methods for preparing trimanganese tetroxide with low bet specific surface area, methods for controlling particle size of trimanganese tetroxide and trimanganese tetroxide product

(1) Purifying Air

[0099]As shown in FIG. 2, the air is purified in the air purification tower 7 which is shown in FIG. 2 by spraying dilute aqueous ammonia with a concentration of 0.5 mol / L according to the proportion of 8 L of the dilute aqueous ammonia per cubic meter of air.

(2) Pretreatment of MnSO4 / H2O

[0100]The concentration of the MnSO4 solution obtained from product prepared by absorption of SO2 fume with manganese dioxide ore is adjusted to 150 g / L (in a container which is not shown in FIG. 2). NH4OH solution with a concentration of 10 mol / L is added so as to adjust pH value of the solution to 5.5. H2S gas is introduced into the MnSO4 solution until pH value reaches 2.5, and then the mixture is separated by pressure-filtration separation to obtain filtrate and solid. The filter residue is discarded. H2O2 solution is added to the filtrate according to the proportion of 2.5 L H2O2 with weight content of 27.5 wt % per cubic meter of the filtrate and the mixture is heated to

(1) Purifying Air

[0103]As shown in FIG. 2, the air is purified in the air purification tower 7 which is shown in FIG. 2 by spraying dilute aqueous ammonia with a concentration of 0.8 mol / L according to the proportion of 9 L of the dilute aqueous ammonia per cubic meter of air.

(2) Pretreatment of MnSO4 / H2O

[0104]The concentration of the MnSO4 solution obtained from product prepared by absorption of SO2 fume with manganese dioxide ore is adjusted to 150 g / L (in a container which is not shown in FIG. 2). NH4OH solution with a concentration of 10 mol / L is added so as to adjust pH value of the solution to 5.8. H2S gas is introduced into the MnSO4 solution until pH value reaches 2.8, and then the mixture is separated by pressure-filtration separation to obtain filtrate and solid. The obtained filter residue is discarded. H2O2 solution is added to the filtrate according to the proportion of 2.5 L H2O2 with weight content of 27.5 wt % per cubic meter of the filtrate and the mixture is h

(1) Purifying Air

[0107]As shown in FIG. 2, the air is purified in the air purification tower 7 which is shown in FIG. 2 by spraying dilute aqueous ammonia with a concentration of 1.0 mol / L according to the proportion of 10 L of the dilute aqueous ammonia per cubic meter of air.

(2) Pretreatment of MnSO4 / H2O

[0108]The concentration of the MnSO4 solution obtained from product prepared by absorption of SO2 fume with manganese dioxide ore is adjusted to 200 g / L (in a container which is not shown in FIG. 2). NH4OH solution with a concentration of 10 mol / L is added so as to adjust pH value of the solution to 6.0. H2S gas is introduced into the MnSO4 solution until pH value reaches 3.0, and then the mixture is separated by pressure-filtration separation to obtain filtrate and solid. The filter residue is discarded. H2O2 solution is added to the filtrate according to the proportion of 2.5 L H2O2 with weight content of 27.5 wt % per cubic meter of the filtrate and the mixture is heated to