Patent ID: 8911796

Claim:
A process for the preparation of a sodium chloride composition comprising an iron complex of tartaric acid wherein between 55 and 90% by weight of the tartaric acid is meso-tartaric acid, the process comprising the steps of spraying an aqueous treatment solution comprising an iron complex of tartaric acid, with between 55 and 90% by weight of said tartaric acid being meso-tartaric acid, and having a pH of between 3 and 5 onto the sodium chloride composition; wherein the aqueous treatment solution comprising the iron complex of tartaric acid, with between 55 and 90% by weight of said tartaric acid being meso-tartaric acid, is obtained by a process comprising: (i) preparing an aqueous mixture comprising between 35 and 65% by weight of a di-alkali metal salt of L-tartaric acid, a di-alkali metal salt of D-tartaric acid, or a mixture of di-alkali metal salts of L-tartaric acid, D-tartaric acid, and optionally meso-tartaric acid, and between 2 and 15% by weight of an alkali metal or alkaline metal hydroxide, (ii) stirring and heating the aqueous mixture for between 3 and 200 hours to a temperature of between 100° C. and its boiling point until between 55 and 90% by weight of tartaric acid has been converted to meso-tartaric acid, (iii) cooling and optionally adding water, (iv) optionally adjusting the pH to a pH of between 5 and 9, (v) stirring and admixing the obtained mixture with an iron(II) salt, an iron(III) salt or a mixture thereof, (vi) and if the pH is outside the range of between 3 and 5, adjusting the pH of the mixture from step (v) to a pH of between 3 and 5.