METHOD OF REGENERATING COMPLEX LITHIUM CHLORIDE-DIMETHYLACETAMIDE SALT IN PRODUCTION OF HIGH-STRENGTH ARAMID FIBRES Russian patent published in 2015 - IPC C07C231/22 C07C233/05 D01F13/00 

FIELD: chemistry.

SUBSTANCE: method of regenerating a complex lithium chloride - dimethylacetamide salt includes neutralising starting solutions, fractionating the stretch bath solution in two columns, vacuum evaporation of the mixture of the still residue of the second column and the settling bath, fractionating the still residue of the vacuum-evaporation apparatus, vacuum fractionation of stripped product of the vacuum-evaporation apparatus and a third column to obtain a solvent, crystallising the concentrated solution of lithium chloride in dimethylacetamide, separating crystals from the solution, separating the crystals on centrifuges and dissolving the crystals in the solvent to obtain the end product. Multi-component starting mixtures containing 0-60% dimethylacetamide (DMAA), 0-70% isobutyl alcohol (IBA), as well as lithium chloride (LiCl), hydrogen chloride, water and impurities - the balance up to 100%, are first separated into lithium chloride-containing mixtures and mixtures which do not contain lithium chloride. The mixtures which do not contain lithium chloride are then separated into mixtures containing DMAA and mixtures which do not contain DMAA. A liquid stream consisting of IBA and water is output from the system; a stream of concentrated lithium chloride is successively directed for heteroazeotropic fractionation, crystallisation and centrifuging, where the complex lithium chloride-dimethylacetamide salt is separated in a liquid phase and a pure complex salt is obtained.

EFFECT: obtaining an end product of high purity for return thereof into the production cycle.

1 dwg