Decreasing the sulphate amount in boric acid production

Boric acid - the product gained via boric acid production from colemanite - containssulphate impurities such as water-soluble sulphates like sodium and magnesium which areformed due to dissolving of the impurities of the substance in the reaction, and water-insolublesulphates like gypsum which deposit during boric acid crystallization and stay in the product.Filtering the water-soluble sulphate impurities can be achieved by effective washing.In this study, we aimed to exchange Ca+2 ions, which form water-insoluble gypsum,with Na+ and H+ ions using strong acidic cation exchanger resins, and to compose water-solublesulphates. For this aim, we studied on solid boric acid samples we got from Eti Mine Works,Emet Boric Acid Factory. We prepared solutions with these samples under the conditions ofcrystallizator feeding solution and treated them with resins. After this process, the resins weredetached and the boric acid was re-crystallized. Sulphate analysis was done on the boric acidsamples prior to and after this process. Moreover, in some of the experiments, we didn?t use anyresins and the solution was crystallized directly by cooling, by which we tried to determine theresin performance. The sulphate amount of the boric acid samples was determined in the HACH2100N model turbidimeter.We can see from the results of the experiments we carried out with resins in the form ofNa+ and H+ that we could do away with sulphate in boric acid in the ratio of %80-90, and whenwe didn?t use resins in the experiments this ratio was %87 on average. When the results wereanalysed, we saw that using resins in the conditions of the experiments wasn?t effective inremoving sulphate. In these experiments, the decrease in the amount of sulphate occurred due tothe crystallization of boric acid by re-dissolving in water.Key Words: Boric Acid, Ion Exchange Resins, Sulphate Impurity