Production of anhydrous, crystalline boron oxide in fluidized bed reactor

Abstract

Industrial production of boron oxide is via fusion of boric acid at 550–1000 °C. The glassy melt thus obtained is then cooled until solid; crushed, ground and then sieved to allow classification according to particle size and distribution. The melting of boric acid is both the most critical and costly stage of all these operations, because boron oxide is highly corrosive to refractories and steel. Our study allows the production of commercial quality anhydrous and crystalline boron oxide without the melting and other processes mentioned above. This is achieved by dehydrating boric acid in a fluidized bed with a gradual increase in the bed temperature up to 250 °C. During this process as the bed temperature is increased gradually, particular attention is paid to keep the dehydration rate below a certain value to prevent melting or sticking, and to secure the desired bulk density value of the product.