Study On The Technology Of Large Particles Sodium Bicarbonate

Sodium bicarbonate is one of the most important inorganic chemical products,which is widely used in chemical industry,light industry,food,pharmaceutical,textile and other aspects of the national economy.Although sodium bicarbonate route is relatively mature,there are some problems such as small size,nonuniform size distribution of sodium bicarbonate products and so on in Tianjin Bohua Yongli Chemical Industry Co.,Ltd.In this study.The sodium bicarbonate products is unable to meet market needs.So we conducted the experiments about the production process of large particles sodium bicarbonate and researched the process of the control of crystal size distribution.The methods of the control of crystal size distribution in the crystallization of large particles sodium bicarbonate were proposed.The main contents include:Firstly,the cooling metastable zone and the local metastable phase diagram in the reactive crystallization process of sodium bicarbonate were measured by visual method.Results showed that the cooling metastable zone is a region of wide ribbon and it narrows with temperature rise,At 20-40?,themetastable zone width of sodium bicarbonate is between 15.6-18.3? in the water.Secondly,the reactive crystallization kinetics of sodium bicarbonate was investigated in a crystallizer by continuous method.The crystallization kinetics of sodium bicarbonate was analysed by ASL model.Therefore,the growth and nucleation rate equations were obtained.Thirdly,the gas-liquid reactive crystallization process of sodium bicarbonate was optimize experimentally.The effect of operational parameters,such as Lye drop rate,seeding policy,on the crystal size distribution were studied.Experimental results show that in order to achieve the average particle size of 40 mesh,these methods that drop rate of 5mL/min,the ratio of solid to liquid of 5%,the operation time of 5h and regularly layout need to be conctrolled.Through various means,we found that experimental products are superior to the Qingdao soda products.Fourthly,the crystal size control of Sodium Bicarbonate was researched in cooling crystallization process.That the agitation rate,cooling rate and seeding effect on the crystal size of sodium bicarbonate were analyzed.we also studied on the granularity theoretical model.The results showed that stirring rate and cooling rate have little effect on crystal size of sodium bicarbonate.In seeding policy,seeding time,seed particle size and seed solid-liquid ratio were the key factor of the crystal size control in cooling crystallization process of sodium bicarbonate.the result theory model and findings of experiments are basically the same.The granularity theoretical model can predict the salary range of seed amount and provide a guidelines of particle size control.The research results of the paper provide reference for study on production of sodium bicarbonate.