Process for treating an acid waste liquid

Claim 1

A method for treating an acid waste liquid containing Fe(III) ions, HNO 3 and HF which has been used for acid washing of metallic materials or articles which comprises: (a) extracting Fe(III) ions from the waste liquid with a first organic solvent selected from the group consisting of di-(2-ethyl-hexyl) phosphoric acid, monododecyl phosphoric acid and mixtures thereof in an organic solvent; (b) adding hydrochloric acid to the extracted waste liquid from step (a) in an amount sufficient to convert any remaining heavy metal ions therein to chlorides; (c) extracting the resulting waste liquid from step (b) with a second organic solvent containing a phosphoric acid ester, a primary, secondary or tertiary amine or a quaternary ammonium chloride which form adducts with HNO 3 and HF in an organic phase; (d) extracting the resulting waste liquid from step (c) with a third organic solvent containing phosphoric acid esters which form adducts with HF and HNO 3 to recover any remaining mineral acids therein; and (e) regenerating each of the first, second and third solvents in respective stages.

Claim 2

A method for treating an acid waste liquid containing Fe(III) ions, HNO 3 and HF which has been used for acid washing of metallic materials or articles which comprises: (a) extracting Fe(III) ions from the waste liquid with a first organic solvent selected from the group consisting of di-(2-ethyl-hexyl) phosphoric acid, monododecyl phosphoric acid and mixtures thereof in an organic solvent; (b) adding hydrochloric acid to the extracted waste liquid from step (a) in an amount sufficient to convert any remaining heavy metal ions therein to chlorides; (c) extracting the resulting waste liquid from step (b) with a second organic solvent containing a phosphoric acid ester, a primary, secondary or tertiary amine or a quaternary ammonium chloride which form adducts with HNO 3 and HF in an organic phase; (d) extracting the resulting waste liquid from step (c) with a third organic solvent containing phosphoric acid esters which form adducts with HF and HNO 3 to recover any remaining mineral acids therein; and (e) regenerating each of the first, second and third solvents in respective stages.

Claim 4

A method for treating an acid waste liquid containing Fe(III) ions, HNO 3 and HF which has been used for acid washing of metallic materials or articles which comprises: (a) extracting Fe(III) ions from the waste liquid with a first organic solvent selected from the group consisting of alkyl phosphoric acids in an organic solvent; (b) adding HCl or H 2 SO 4 to the extracted waste liquid from step (a) in an amount sufficient to convert any remaining heavy metal ions therein to chlorides or sulfates; (c) extracting the resulting waste liquid from step (b) with a second organic solvent containing a phosphoric acid ester, a primary, secondary or tertiary amine or a quaternary ammonium chloride which form adducts with HNO 3 and HF in an organic phase; (d) extracting the resulting waste liquid from step (c) with a third organic solvent containing phosphoric acid esters which form adducts with HF and HNO 3 to recover any remaining mineral acids therein; and (e) regenerating each of the first, second and third solvents in respective stages.

Claim 5

A method for treating an acid waste liquid containing Fe(III) ions, HNO 3 and HF which has been used for acid washing of metallic materials or articles which comprises: (a) extracting Fe(III) ions from the waste liquid with a first organic solvent selected from the group consisting of alkyl phosphoric acids in an organic solvent; (b) adding HCl or H 2 SO 4 to the extracted waste liquid from step (a) in an amount sufficient to convert any remaining heavy metal ions therein to chlorides or sulfates; (c) extracting the resulting waste liquid from step (b) with a second organic solvent containing a phosphoric acid ester, a primary, secondary or tertiary amine or a quaternary ammonium chloride which form adducts with HNO 3 and HF in an organic phase; (d) extracting the resulting waste liquid from step (c) with a third organic solvent containing phosphoric acid esters which form adducts with HF and HNO 3 to recover any remaining mineral acids therein; and (e) regenerating each of the first, second and third solvents in respective stages.

Claim 7

A method for treating an acid waste liquid containing Fe(III) ions, HNO 3 and HF which has been used for acid washing of metallic materials or articles which comprises: (a) extracting Fe (III) ions from the waste liquid with a first organic solvent (A) which contains one or more compounds selected from the group of alkyl phosphoric acids, together with a hydrocarbon as diluent; (b) regenerating the used solvent (A) with HCl; (c) adding HCl or H 2 SO 4 to the extracted waste liquid from step (a) in an at least stoichiometric amount to convert any remaining heavy metal ions therein to chlorides or sulfates; (d) extracting the resulting waste liquid from step (c) with a second organic solvent (B), which contains one or more compounds selected from the group of alkyl phosphoric acid esters, together with a hydrocarbon as diluent to recover HNO 3 and HF in an organic phase; (e) regenerating the organic solvent (B) and recovering HNO 3 and HF by stripping the organic phase with water.

Claim 8

A method for treating an acid waste liquid containing Fe(III) ions, HNO 3 and HF which has been used for acid washing of metallic materials or articles which comprises: (a) extracting Fe (III) ions from the waste liquid with a first organic solvent (A) which contains one or more compounds selected from the group of alkyl phosphoric acids, together with a hydrocarbon as diluent; (b) regenerating the used solvent (A) with HCl; (c) adding HCl or H 2 SO 4 to the extracted waste liquid from step (a) in an at least stoichiometric amount to convert any remaining heavy metal ions therein to chlorides or sulfates; (d) extracting the resulting waste liquid from step (c) with a second organic solvent (B), which contains one or more compounds selected from the group of alkyl phosphoric acid esters, together with a hydrocarbon as diluent to recover HNO 3 and HF in an organic phase; (e) regenerating the organic solvent (B) and recovering HNO 3 and HF by stripping the organic phase with water.

Claim 10

A method for treating an acid waste liquid containing Fe(III) ions, HNO 3 and HF which has been used for acid washing of metallic materials or articles which comprises: (a) extracting Fe (III) ions from the waste liquid with a first organic solvent (A) which contains one or more compounds selected from the group of alkyl phosphoric acids, together with a hydrocarbon as diluent; (b) regenerating the used solvent (A) with HCl; (c) adding HCl or H 2 SO 4 to the extracted waste liquid from step (a) in an at least stoichiometric amount to convert any remaining heavy metal ions therein to chlorides or sulfates; (d) extracting the resulting waste liquid from step (c) with a second organic solvent (B) which contains one or more compounds selected from the group of alkyl phosphoric acid esters, together with a hydrocarbon as diluent to recover HNO 3 and HF in an organic phase; (e) scrubbing organic solvent (B) which contains co-extracted HNO 3 and HF by contacting it with a HNO 3 solution whereby the HNO 3 has a larger distribution coefficient than HF to recover organic solvent (B) containing only HNO 3 and then regenerating solvent (B) by stripping it with water.

Claim 11

A method for treating an acid waste liquid containing Fe(III) ions, HNO 3 and HF which has been used for acid washing of metallic materials or articles which comprises: (a) extracting Fe (III) ions from the waste liquid with a first organic solvent (A) which contains one or more compounds selected from the group of alkyl phosphoric acids, together with a hydrocarbon as diluent; (b) regenerating the used solvent (A) with HCl; (c) adding HCl or H 2 SO 4 to the extracted waste liquid from step (a) in an at least stoichiometric amount to convert any remaining heavy metal ions therein to chlorides or sulfates; (d) extracting the resulting waste liquid from step (c) with a second organic solvent (B) which contains one or more compounds selected from the group of alkyl phosphoric acid esters, together with a hydrocarbon as diluent to recover HNO 3 and HF in an organic phase; (e) scrubbing organic solvent (B) which contains co-extracted HNO 3 and HF by contacting it with a HNO 3 solution whereby the HNO 3 has a larger distribution coefficient than HF to recover organic solvent (B) containing only HNO 3 and then regenerating solvent (B) by stripping it with water.