Process for recovery of waste H.sub.2 SO.sub.4 and HCl
AssigneeSolex Research Corporation of Japan
InventorsMorio Watanabe, Sanji Nishimura
Life of this patent
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Abstract
This invention relates to a process for recovery of waste H.sub.2 SO.sub.4 and HCl which are used for pickling metallic materials and articles and contain a large quantities of Fe ions. Furthermore, it offers a process for the recovery of H.sub.2 SO.sub.4 and HCl from waste H.sub.2 SO.sub.4 which contains large amounts of Fe ions after removal of Ti ions by a hydrolysis process in the production of TiO.sub.2 and also for the recovery of high-purity electrolytic iron or iron hydroxide.
Claims29
A process for the recovery of waste H.sub.2 SO.sub.4 and HCl from aqueous metal pickling solutions which contain large amounts of Fe ions comprising:
- 1. converting the Fe.sup.2+ ions in the waste to Fe.sup.3+ ions in an oxidation reduction cell wherein the waste solution is the anolyte and the catholyte is an HCl solution containing Fe.sup.3+ ions, the used catholyte thus containing Fe.sup.2+ ions;
- 2. extracting the Fe.sup.3+ ions from the anolyte from step (1) with an organic solvent A to recover the HCl or H.sub.2 SO.sub.4 ;
- 3. stripping the Fe.sup.3+ ions from the used solvent A by contacting it with an HCl containing stripping solution and thus regenerating solvent A for reuse;
- 4. recovering the Fe.sup.3+ ions from the HCl stripping solution by liquid-liquid extraction thereof with an organic solvent B to form an FeCl.sub.3 -complex therein;
- 5. regenerating solvent B by contacting it with an aqueous extractant to extract the FeCl.sub.3 therefrom and using the Fe.sup.3+ containing extractant as the catholyte in step (1);
- 6. recovering the iron values in the used catholyte from step (1) by diaphragm electrolysis;
- and
- 7. regnerating the HCl strip solution from step (4) by subjecting to the diaphragm electrolysis of step (6).
A process for the recovery of waste HCl from an aqueous metal pickling solution which contains large amounts of Fe ions comprising:
- 1. converting the Fe.sup.2+ ions in the waste to Fe.sup.3+ ions in an oxidation-reduction cell wherein the waste solution is the anolyte and the catholyte is an HCl solution containing Fe.sup.3+ ions, the used catholyte thus containing Fe.sup.2+ ions;
- 2. extracting the Fe.sup.3+ ions from the anolyte from step 1. with an organic solvent C to form an FeCl.sub.3 -complex therein and to produce an aqueous raffinate;
- 3. regnerating solvent C by contacting it with an aqueous extractant to extract the Fe.sup.3+ therefrom and using the Fe.sup.3+ containing extractant as the catholyte in step (1);
- 4. recovering the iron values in the used catholyte from step (1) by diaphragm electrolysis;
- and
- 5. subjecting the raffinate from step (2) to the diaphragm electrolysis of step (4) to recover HCl therefrom.
Dependencies are inferred from the claim text.