摘要：

采用钙源化学-絮凝沉淀法对稀土冶炼含氟废水进行了处理及资源回收利用，探讨了pH、CaCl₂投加量、反应温度等条件对氟化钙制备的影响，分析了深度除氟的主要影响参数，并结合SEM和XRD等表征方法研究了氟化钙制备和脱氟机理。结果表明：在pH=7，CaCl₂投加量为13.5 g/L，温度为50 ℃的条件下，可制备得到品位为87.79%的粗氟化钙；将其作为晶种返回净化后原液中搅拌1 h，得到品位为95.05%的工业级氟化钙；向除氟滤液添加3.0 g/L的CaCl₂溶液，溶液残余氟质量浓度降至7.76 mg/L，满足《稀土工业污染物排放标准》（GB 26451—2011）中有关氟浓度排放的最低标准，除氟率达99.82%。

关键词: 化学-絮凝沉淀, 含氟废水, 氟化钙, 深度除氟, 除氟率

Abstract:

The fluorine-containing wastewater from rare earth smelting was treated and recycled by calcium-source chemical-flocculation precipitation method. The discussion focused on the impact of pH, the amount of CaCl₂ added,and reaction temperature on the synthesis of calcium fluoride. Furthermore, the primary parameters influencing the efficiency of deep fluoride removal were analyzed. Additionally, the preparation process and the defluorination mechanism of calcium fluoride were examined using SEM and XRD characterization techniques. The results indicated that when pH was set to 7, with CaCl₂ dosage of 13.5 g/L and temperature of 50 ℃, a crude calcium fluoride with purity of 87.79% could be synthesized. This crude calcium fluoride was then used as a seed in the purified stock solution and stirred for 1 hour, resulting in the production of industrial-grade calcium fluoride with a purity of 95.05%. After adding a 3.0 g/L CaCl₂ solution to the fluoride-removed filtrate, the residual fluoride concentration in the solution decreased to 7.76 mg/L, meeting the minimum fluorine emission standard specified in the Emission Standards for Rare Earth Industrial Pollutants (GB 26451—2011). The fluoride removal efficiency achieved was an impressive 99.82%.

Key words: chemical-flocculation precipitation, fluorine-containing wastewater, calcium fluoride, deep fluoride removal, fluoride removal rate

中图分类号: 

• X703.1