Extracting B2O3 from calcined boron mud using molten sodium hydroxide

Extracting B2O3 from calcined boron mud (CBM) was studied. The effect of factors such as reaction temperature and NaOH-to-CBM mass ratio on B2O3 extraction efficiency was investigated. The results show that increasing reaction temperature and NaOH-to-CBM mass ratio increases B2O3 extraction efficiency. There are two stages for the B2O3 extracting process: 0-20 min is the first stage, which is rapid; 20-50 min is the second stage, which is slower than the first stage. The overall extracting process follows the shrinking core model, and the first and second stages are determined to obey the surface chemical reaction model and the diffusion through the products layer model, respectively. The activation energies of the first and second stages are calculated to be 41.74 and 15.43 kJ center dot mol(-1), respectively. The B2O3 extracting kinetics equations of the first and second stages are also obtained.