低品位伴生萤石制备氢氟酸机理研究

    Mechanism of Preparing Hydrofluoric Acid from Low-grade Associated Fluorite

    • 摘要: 【目的】单一型萤石是目前硫酸法生产氢氟酸的主要原料,但是目前单一型萤石储量不足,保障年限仅十余年。伴生型萤石储量约为单一型萤石的两倍,但是目前缺少使用伴生型萤石为原料生产氢氟酸的研究,制约了其高值化利用。【方法】本文以品位为99.1%的高品位单一型萤石与纯度为85.2%的低品位伴生型萤石为研究对象,研究在不同温度、液固摩尔比及时间条件下与浓硫酸的反应过程。【结果】发现在200 ℃、反应4 h,单一型萤石产酸的较佳液固摩尔比为1.25∶1,HF转化率为98.1%,伴生型萤石产酸时所需的浓硫酸用量更高,较佳液固摩尔比为1.5∶1,HF转化率为82.1%。单一型萤石反应产生的氟石膏晶体颗粒大,结晶度好且表面致密,而伴生型萤石反应产生的氟石膏晶体颗粒小,晶体形状不规则且呈紧密堆积状。【结论】因此,伴生型萤石反应产生的氟石膏颗粒内部存在明显的螺旋状花纹,且团聚现象比单一型萤石更严重,阻碍了制酸反应的进行,是HF转化效率低的主要原因。

       

      Abstract: ObjectiveSingle type fluorite is currently the primary raw material for hydrofluoric acid production. However, its reserves are insufficient, with a guarantee life of around ten years. The reserve of associated fluorite is approximately twice that of single type fluorite. Nevertheless, the lack of research on the associated fluorite as a raw material for hydrofluoric acid production impedes its high-value utilization. MethodIn this article, high grade single type fluorite with a grade of 99.1% and low-grade associated type fluorite with a purity of 85.2% were studied. The reaction processes of high purity fluorite and low purity associated fluorite with concentrated sulfuric acid at varying conditions of temperature, time, and molar ratios of liquid to solid were investigated. ResultAt a temperature of 200 ℃ for 4 h, the optimal molar ratio of liquid to solid for single fluorite was 1.25∶1, with a conversion rate of HF up to 98.1%. When producing acid from associated fluorite, the dosage of concentrated sulfuric acid was higher at an optimal molar ratio of liquid to solid of 1.5∶1 and a conversion rate of HF up to 82.1%. The gypsum crystal produced by single fluorite had a large particle size, good crystallinity and a dense surface. However, the gypsum crystals produced by associated fluorite were small in particle size, irregular in shape and closely packed. ConclusionTherefore, distinct spiral patterns were evident in the gypsum particles produced by associated fluorite, and the agglomeration phenomenon of gypsum produced by associated fluorite was more serious than that of single fluorite, which hindered the efficient acid production reaction.

       

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