The Research On Removing Iron From Aluminum Sulfate Solution With Fluorine Iron And Its High Value Added Recovery Technology

Aluminum sulphate solution with F^- as the former solution of the electrolytic aluminum media is mixed by the waste hydrofluoric acid with the aluminum sulphate solution which prepared by H₂SO₄ leaching poor quality bauxite. The impurity iron in the solution has effect on the purity and performance of electrolytic aluminum. So the removal of iron from the solution is very important to the next production. At present, there are many studies on the removing iron from the simple aluminum sulphate, but not with F^-. It is more difficult to remove iron when added F^-.The paper makes the research on the removal iron from the Aluminum sulphate solution with F^-. By the choosing the ways of removing iron, electrolytic electrode position, potassium permanganate Oxidation-Precipitation and organic solvent extraction were studied. Extraction solvent was regenerated by hydrothermal stripping technology instead of the multistage stripping process with H₂SO₄ was proposed. And the application of hydrothermal stripping recovered highly pure and well-distributed size iron oxide powers which can be used as iron oxide red pigment. Hydrothermal stripping technology had advantage of simplifying the process flow-sheet, decreasing the investment cost, increasing the added value utilization and reducing the environmental pollution and showed economy profit and social benefit.The concrete research contents are as follows.(1) To choose methods for removing iron according to lots of iron and the remained F^-. Organic solvent extraction can deeply removed iron with lossless aluminum and fluoride with organic solvent extraction of the system Tri-n-Octylamine(TOA)-Tributyl Phosphate (TBP)-Sulfonated Kerosene.(2) Extraction of iron with the system Tri-n-Octylamine(TOA)-Tributyl Phosphate (TBP)- Sulfonated Kerosene for the separation.The factors on the iron of extraction radio such as contact time, TOA concentration, initial pH value, O/A, ect. It determined the best technology of the iron extraction, which was on the condition of 35%TOA+10%TBP+ Sulfonated Kerosene, contact time 5 min, initial pH value 0.8, O/A=1.25. By four times extraction the iron of extraction radio was 99.1%, and the iron concentration is reduced to 0.07 g/L.(3) Extraction solvent regeneration by hydrothermal stripping. Some factors on hydrothermal stripping from iron-loaded organic phase of 35%TOA+10%TBP+Sulfonated Kerosene, such as initial pH value of the aqueous phase, A'/O', stripping temperature and time. It gave the best technology of hydrothermal stripping, which is on the condition of that the initial pH value 12 of the aqueous phase, A'/O'=1, stripping temperature 165℃, stripping time 4 h.(4) Hydrothermal stripping from iron-loaded organic phase.Iron oxide powder was prepared by hydrothermal stripping. The effects of the stripping temperature, the initial pH value of the aqueous phase, A'/O' on the nanoparticle were investigated. The powder obtained at the stripping temperature of 165℃above was well crystalized and is quasi-sphered nanoα-Fe₂O₃ by means of TEM and XRD.The particle size would become larger by enhancing the temperature, increasing the reaction time and decreasing the A'/O'. And the largest size powder is abtained at pH value 7 with the other same conditions.