Solvent Extraction of Iron From Aluminum Sulfate With Tertiary Amine(N235)

Iron was removed from aluminum sulfate solution with tertiary amine(N235)by solvent extraction.The effects of the aqueous phase pH,volume fraction of extractant and extraction temperature on extraction efficiency of iron were studied.The effect of aliphatic carboxylic acid,1-capryl and TBP on phases separation were examined.The experimental results showed that all of three organic reagents can improve the phase separation,but aliphatic carboxylic acid and 1-capryl inhibit the extraction of iron with N235,TBP has synergy on solvent extraction of iron with N235.Using the organic phase of composition of 30%N235-10%TBP-55%kerosene,at the conditions of aqueous phase pH of 0.5-1.0 and the extraction temperature of 25 ℃,the mass concentration of Fe in water phase can be reduced to 0.019 g/L from 8.36 g/L,the total extraction efficiency could reach 99.77% by three-stage continuous countercurrent extraction.Aluminum sulfate with the content of Fe less than 0.005% has been obtained when the raffinate is concentrated and crystallized.