提高湿法磷酸副产氟硅酸质量的措施

Measures to Improve the Quality of By-product Fluorosilicic Acid from the Wet Process Phosphoric Acid Production

湿法磷酸副产的氟硅酸可用做各种氟盐的原料 ,用途较广 ,但因其浓度低、沉淀物多 ,制约了它的应用范围 ,又会引起环境污染。阐述它的反应机理 ,指出氟硅酸中n(HF) /n(SiF4 )≥ 2时不会析出SiO2 ,要求浓磷酸中ω(P2 O5) =5 0 %～ 5 5 % ,H2 SiF6的得率高。据此指出提高湿法磷酸副产氟硅酸质量的措施是采用P2 O5含量高、杂质含量低的磷矿 ,控制浓磷酸中的ω(P2 O5)为 5 0 %～ 5 2 % ,氟硅酸中n(HF) /n(SiF4 )≥ 2、ω(P2 O5)为 6 0～ 180mg/kg ,并应及时清理氟吸收系统的结垢物 ,可制得ω(H2 SiF6)为 2 5 %～ 2 8%、清澈透明。

The by product fluorosilicic acid from wet process production of phosphoric acid can be used as the raw material for many fluorides,so,it has many uses.However,it has a low concentration and much sedimentation,consequently,the range of its use is limited,on the other hand,it can cause environmental pollution.The author describes the reaction mechanism,points it out that no SiO 2 will separate out with n (HF)/ n (SiF 4)≥2,and requires that ω (Ρ 2O 5) be equal to 50%～55% to have a high H 2SiF 6 recovery percentage.From the reaction mechanism,the author proposes measures to improve the quality of the by product fluorosilicic acid from wet process production of phosphoric acid:using phosphate ore with a high P 2O 5 content and a low impurities content;controlling ω (P 2O 5) at 50%～52% in the concentrated phosphoric acid, n (HF)/ n (SiF 4)≥2 and ω (P 2O 5)=60～180?mg/kg in fluorosilicic acid;cleaning out in time sediments from the fluorine absorption system.With these measures implemented,limpid high quality fluorosilicic acid with ω (H 2SiF 6)=25%～28% can be produced.