Production of Anhydrous, Crystalline Borax in a Fluidized Bed

Abstract

Industrial production of anhydrous borax is via fusion of borax deca- or pentahydrate at 800−1000 °C. The glassy melt obtained thus is then cooled to solidify, crushed, ground, and then sieved to be classified according to its particle size and distribution. Since molten borax is highly corrosive to refractories and steel, among all these operations, the melting of borax is the most critical and the most costly. Our study gives way to production of commercial quality anhydrous and crystalline borax by eliminating melting and other above-mentioned operations. For this purpose, borax pentahydrate is dehydrated in a fluidized bed with gradually increasing the bed temperature up to 550 °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 secure the bulk density of the product at levels greater than 0.3 g/cm3.