硝酸磷肥生产过程中酸解液除氟的研究

Removal effect research of fluoride from the acid digestion liquor in production process of nitrophosphate fertilizer

硝酸磷肥生产过程中氟的存在不仅会影响企业的正常生产,而且会造成严重环境污染,寻找一种经济可行的除氟方案迫在眉睫。分析了酸解液的组成,研究了脱氟剂的种类、添加量以及反应时间和反应温度对酸解液除氟效果的影响。结果表明,酸解液中的氟是以H_2SiF_6(0.68%F-)和HF(0.10%F-)两种形式存在;当脱氟剂为硝酸钠,反应时间为1 h,反应温度为25℃,添加量为理论用量的400%时,除氟率为64.836%;同样反应条件下,硝酸钾为脱氟剂时,除氟率为79.224%。通过表征分析表明,无论何种脱氟剂,均可得到相应纯度较高的氟硅酸盐产品。此次实验结果可为硝酸磷肥企业脱氟工艺的设计提供一定的理论指导。

The presence of fluorine in the acid digestion liquor not only affected the normal production of enterprises,but also caused the pollution to ecosystems. Therefore,it is urgent to find an economically feasible solution to remove fluorine. In this paper,the composition of acid digestion liquor was firstly analyzed and the influences of reaction time,temperature and defluorinated agents on the removal effect of fluoride from the acid digestion liquor in production process of nitrophosphate fertilizer was investigated. It was found that fluoride was present in two forms of H2SiF6（0. 68% F-） and HF（0. 10% F-）. The fluoride removal efficiency could reach 64. 836%at 25 ℃ when 400% excess of NaNO3 was added in the pure fluoride solution after 1 h. However,the fluoride removal efficiency reached 79. 224% under the same experimental conditions using KNO3 as precipitant. Precipitation experiments revealed that the addition of KNO3/Na NO3 would remove the fluoride eff ectively,and the obtained precipitates were the fluorosilicate products with high purity. These obtained results provided basic data which can be utilized for the removal of fluoride in production process of nitrophosphate fertilizer.