| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing polyferric sulfate by suppressing viscosity rising on dissolving ferric oxide sludge and improving filtrability at the time of filtering impurities after dissolving ferric oxide at the time when producing polyferric sulfate using ferric oxide sludge containing silica, such as red water sludge, as an iron raw material. SOLUTION: This method for producing polyferric sulfate comprises the steps of mixing concentrated sulfuric acid with less than the required amount of silica-containing ferric oxide sludge to dissolve the ferric oxide; mixing diluting water after dissolving; and then further mixing the remaining silica-containing ferric oxide sludge to dissolve the ferric oxide; then filtering the solution after dissolving to obtain polyferric sulfide; at the same time, washing the separated filtered sludge with water; solid-liquid separating the washed sludge after washing; and reutilizing the separated washing water as the diluting water. In this method, time for dissolving ferric oxide in the silica-containing ferric oxide sludge can be shortened, filtrability of remains after dissolution can be improved, and water contamination problems never occur. COPYRIGHT: (C)2007,JPO&INPIT
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