GB910541A - Improvements relating to the recovery of boron values from alkaline liquors - Google Patents

Abstract

Boron values are recovered from aqueous alkaline solutions containing boron ions derived from an alkali metal borate or boric acid, by contacting the solution with 1,8-naphthalene diol or with an aromatic polyol in which two hydroxyl groups are separated by not more than three carbon atoms of which, when there are three carbon atoms, at least one is extra nuclear, to form a boron-containing complex of the polyol, separating the complex from the solution and decomposing it to recover the polyol and recover the boron values. The polyol may be a phenylglycol, an aromatic mono-ether of glycerol, an aromatic compound having hydroxyl groups in the 1,2 positions, or a methylol phenol or naphthol. The solution containing boron ions may be a brine derived from a natural source and may contain sodium or potassium metaborates, tetraborates or pentaborates, and other salts, e.g. sodium and potassium chlorides, sulphates, carbonates, phosphates, sulphides and arsenates; these other salts remain in the aqueous solution. The polyol alone may be mixed with the aqueous solution, or may be added as a solution in a water-immiscible solvent, e.g. benzene, isopropyl ether, diethyl ether, tributyl phosphate, kerosene or a monohydric alcohol having 8 to 17 carbon atoms. The complex appears as a precipitate or as a solution in the organic phase. The complex is reacted with an acid, e.g. sulphuric acid, to obtain an aqueous solution of boric acid and sodium and potassium sulphates, and to regenerate the polyol which is either separated in the organic solvent phase, when present, or is stripped with an organic solvent. The aqueous solution is then evaporated sufficiently to crystallize boric acid at 35 DEG C. but to leave sodium and potassium sulphates in solution. After removal of boric acid crystals the solution is evaporated still further to cause the sulphates to crystallize at a higher temperature leaving the boric acid in solution. Other acids which may be used to decompose the complex are sulphurous, hydrochloric, nitric and perchloric acids. In examples brines containing borax are contacted with 1,8-naphthalenediol, phenyl-glycol in iso-octanol, 4-isooctyl-6-chloro-saligenin in kerosene, and 2,3-naphthalene-diol in a mixture of octanol and tributyl phosphate, and boric acid is recovered by reacting the complexes formed with sulphuric acid. Other polyols mentioned are 1,2-diphenyl glycol, methyl phenyl glycol, 3,5-xylenyl ether of p-tertiary-amyl-phenyl-ether of glycerol, octyl-, nonyl-, dinonyl, phenyl- and dodecyl-saligenins, 2,6-dimethylol-4-octyl phenol and methylolnaphthol. The above-mentioned boron-containing complexes may be added to gasoline together with tetraethyl lead and a halide scavenging agent. The boron compound is added in an amount sufficient to provide from 0,002 to 0,1% by weight based on the gasoline. Specification 625,216 is referred to.ALSO:Boron-containing complexes are prepared from aqueous alkaline solutions containing boron ions derived from an alkali metal borate or boric acid, by contacting the solution with 1,8-naphthalene diol or with an aromatic polyol in which two hydroxyl groups are separated by not more than three carbon atoms of which, when there are three carbon atoms, at least one is extra nuclear. The polyol may be a phenylglycol, an aromatic mono-ether of glycerol, an aromatic compound having hydroxyl groups in the 1,2 positions, or a methylol phenol or naphthol. The solution containing boron ions may be a brine derived from a natural source and may contain sodium or potassium metaborates, tetraborates or pentaborates, and other salts, e.g. sodium and potassium chlorides, sulphates, carbonates, phosphates, sulphides and arsenates; these other salts remain in the aqueous solution. The polyol alone may be mixed with the aqueous solution, or may be added as a solution in a water-immiscible solvent, e.g. benzene, isopropyl ether, diethyl ether, tributyl phosphate, kerosene or a monohydric alcohol having 8 to 17 carbon atoms. The complex appears as a precipitate or as a solution in the organic phase. The complex may be reacted with an acid e.g. sulphuric acid, to obtain an aqueous solution of boric acid and sodium and potassium sulphates, and to regenerate the polyol. In examples brines containing borax are contacted with 1,8-naphthalenediol, phenyl-glycol in isooctanol, 4-isooctyl-6-chloro-saligenin in kerosene, and 2,3-naphthalenediol in a mixture of octanol and tributyl phosphate, and boric acid is recovered by reacting the complexes formed with sulphuric acid. Other polyols mentioned are 1,2-diphenyl glycol, methyl phenyl glycol, 3,5-xylenyl ether of glycerol, p-tertiary-butyl phenyl ether of glycerol, p-tertiary-amyl-phenyl-ether of glycerol, octyl-, nonyl-, dinonyl-, phenyl- and dodecyl-saligenins, 2,6-dimethylol - 4 - octyl phenol and methylolnaphthol. 4-Iso-octyl-6-chlorosaligenin is prepared by chlorinating 4-iso-octyl-phenol to obtain isooctyl-chloro-phenol, which is then reacted with formaldehyde and aqueous sodium hydroxide. Specification 625,216 is referred to.