Reducing iron content in crude phosphoric acid by potassium ferrocyanide

Abstract

<span style="font-size:12.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">The iron content was removed from crude wet process phosphoric acid produced by treating the Abu-Tartor phosphate ore with sulphuric acid, using potassium ferrocyanide as a precipitating agent. The iron content in the phosphoric acid filtrate is determined as ferric oxide by titration with K₂Cr₂O₇ and using barium diphenyl amine sulphonate solution as indicator. The precipitates were washed, dried and converted to ferric oxide by heating at 100°C for 3 h. A sample of both the ferric -ferrocyanide and ferric oxide were characterized by using X-ray diffraction. It was found that the weight of the ferric ferrocyanide precipitate increases as the volume of the potassium ferrocyanide increases while the iron content in the phosphoric filtrate decreases. The results indicate that 30 kgm of potassium ferrocyanide is enough to precipitate about 60% of the original iron content in 1.46 ton of phosphoric acid with 8.2% loss in P₂O₅ from the original percentage.</span>