A Study On Reactive Crystallization Process And Agglomeration Behavior Of Sodium Percarbonate

AS a new-style oxidation bleaching agent, sodium percarbonate is widely used as an assistant in the synthesis of abstergent. Compared with the overseas products, sodium percarbonate which made in china laid in an inferior position because of the little bulk density, rough granule surface, nonuniform particle size, poor stability and so on. Therefore, it is necessary to improve the producing technique of sodium percarbonate. In this thesis, the reaction crystallization process of sodium percarbonate was systematically investigated.The solubility of sodium percarbonate in water was measured using the laser method. Some influence factors on solubility, such as temperature and the quantity of the salting-out agent were experimentally studied. According to the experiments, we have drawn a conclusion that by adding the salting-out agent into the reaction solution is more efficacious for precipitation of sodium percarbonate than by lowing down the crystallization temperature. So in this work the method of adding salting-out agent into the solution under the room temperature was used to improve the production yield.The optimal operation conditions for the reactive crystallization process of granular sodium percarbonate were obtained after studying the influences of temperature, feed composition, dropping speed, stir speed, quantity of salting-out agent and recirculating of mother solution on the bulk density, content of effectual oxygen, stability, and yield of product.The kinetics models of the reactive crystallization process of sodium percarbonate were built on the basis of the population balance and the quality balance equations. The reason of agglomeration of sodium percarbonate was explored in order to improve the bulk density and make the surface of granules smoother. Finally the crystallization kinetics with agglomeration agent existing in the system was investigated, and the agglomeration growth model of sodium percarbonate particles was obtained which is different from the traditional crystal growth models.The paper supplied a data basis for the further study and the industrial crystallization production of sodium percarbonate.