一步法制备氟化钠和二氧化硅的实验研究

STUDY ON PREPARATION OF SODIUM FLUORIDE AND SILICON DIOXIDE BY ONE-STEP METHOD

以氟硅酸和碳酸钠为原料,在氟硅酸与碳酸钠物质的量比1.0∶3.5,反应温度90～95℃,反应时间150～180min,pH=6.6～7的条件下,一步沉降法制备氟化钠和二氧化硅。对生成的共沉淀物氟化钠和二氧化硅利用双锥分离器,采用母液漂浮法,控制母液的上升速度在4.0～5.0mm/s之间,实现了氟化钠和二氧化硅的有效分离,氟化钠的回收率可达99%以上,漂浮物中二氧化硅的回收率在96%以上,氟化钠和二氧化硅的产品质量分别符合或超过国标GB4293-84和国标GB10571-89。

Sodium fluoride and silicon dioxide was prepared from fluosilicate acid and sodium hydrocarbonate by one-step sedimentation method. The ratio of fluosilicate acid to sodium carbonate was 1. 0∶ 3. 5（ mol∶ mol） ,and the reaction was proceeded for 150 ～ 180 min at 90 ～ 95 ℃ under pH = 6. 6 ～ 7. The product mixture of sodium fluoride and silicon dioxide was separated by mother liquid floating method with double-biconical separator. The ascending rate of mother liquor was controlled to 4. 0 ～ 5. 0 mm/s. The recovery yield of sodium fluoride arrived to above 99% and the recovery yield of silicon dioxide was above 96%. The products of sodium fluoride and silicon dioxide are coincided with national standard GB4293-84 and GB10571-89.