Controlling the formation of Na2ZrSiO5 in alkali fusion process for zirconium oxychloride production

• We discussed the effect of roasting temperature on the formation of Na2ZrSiO5.
• We discussed the effect of NaOH/zircon mole ratio on the formation of Na2ZrSiO5.
• We discussed the effect of particle size of zircon sand on the formation of Na2ZrSiO5.
• The mechanism was studied.
• The amount of Na2ZrSiO5 significantly decreased under the optimum conditions.

In the alkali fusion process for the production of zirconium oxychloride, the formation of the water-insoluble by-product, Na2ZrSiO5, largely affects NaOH recovery and results in the formation of silicon slags. Thus, controlling Na2ZrSiO5 formation is necessary. In this paper, we studied the effects of roasting temperature, NaOH/zircon mole ratio, and particle size of zircon sand on Na2ZrSiO5 formation. The optimum reaction parameters, when the roasting time was 1 h, were as follows: ⩾95 μm average particle size of zircon sand, 6:1 NaOH/zircon mole ratio, and 750 °C roasting temperature. To avoid an uneven roasting temperature during alkali fusion, the use of a rotary kiln reactor is recommended. The amount of Na2ZrSiO5 was significantly decreased under these optimum conditions, and the content of Na2O was reduced from 7.049% to only 2.21% after three water-leaching cycles.

Figure optionsDownload as PowerPoint slide