Abstract:

A sodium-roasting process was employed for removing silicon from high-silicon brucite as raw material,using NaOH as sodium treatment reagent.The effects of NaOH content,roasting temperature and roasting time etc.on Si content of the water-washed roasting products were investigated,respectively.The structure and spectroscopic characteristics of roasting products and the water-washed residues in different roasting temperature were analyzed.The mechanism of removing silicon from high-silicon brucite by sodium-roasting process was revealed.The results indicated that optimal processing parameters were roasting temperature of 650 ℃,3 times theoretical amount of NaOH and roasting time of 3 h.Under these conditions,Na⁺ substituted Mg²⁺ of Mg₂SiO₄ obtained by serpentine decomposition,and the final products were Na₄SiO₄.The mass fraction of Si in water washed roasting products reached 1.89% and the extraction ratio of Si reached 90.1%.

Key words: high-silicon brucite, sodium roasting, serpentine, silicon removal