化工学报 ›› 2023, Vol. 74 ›› Issue (3): 1161-1174.DOI: 10.11949/0438-1157.20221479

• 分离工程 • 上一篇    下一篇

铬铁矿在HCl-HF体系中的分解行为

陈号(), 田仪娟, 全学军(), 蒋子文, 李纲   

  1. 重庆理工大学化学化工学院,重庆 400054
  • 收稿日期:2022-11-14 修回日期:2023-02-11 出版日期:2023-03-05 发布日期:2023-04-19
  • 通讯作者: 全学军
  • 作者简介:陈号(1996—),男,硕士研究生,309471372@qq.com
  • 基金资助:
    重庆英才计划项目(CQYC20210309538)

Decomposition behaviour of chromite in the HCl-HF system

Hao CHEN(), Yijuan TIAN, Xuejun QUAN(), Ziwen JIANG, Gang LI   

  1. College of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
  • Received:2022-11-14 Revised:2023-02-11 Online:2023-03-05 Published:2023-04-19
  • Contact: Xuejun QUAN

摘要:

铬铁矿酸浸分解制铬盐因其过程可以避免危险性物质六价铬[Cr(Ⅵ)]的产生而显示出较大应用前景,以盐酸为酸浸剂可以利用金属离子在盐酸中溶解度的差异,使工艺具有易于回收剩余酸和铬盐的特点。但是,也因为溶解平衡,使盐酸浸出铬铁矿的浸出效率较低,为了提高铬铁矿盐酸浸出过程的效率,提出了氢氟酸(HF)强化铬铁矿盐酸浸出的新工艺。在前期工作基础上,研究了HF强化铬铁矿盐酸浸出的规律、动力学及过程机理。结果表明,HF可以大大强化铬铁矿中Cr、Fe的浸出速率,且随HF用量增加而增大;而其中Al、Mg的浸出速率随HF用量的增加呈现先增加后减小的趋势,其主要原因是HF用量大时可以促进体系中含Al、Mg、Si物质形成Mg2SiO4、(Mg, ‍Al)SiO3、Al2SiO5等结晶性硅酸盐,进入渣相中。这一发现为选择适当的浸出条件,实现浸出液中Cr与Al、Mg等杂质的更好分离提供了依据。在较高HF用量下,Cr、Fe、Al、Mg的浸出率可分别达到约92%、94%、17%、14%。HF的用量不仅影响铬铁矿盐酸浸出过程动力学的控制步骤,在促进浸出液中含Al、Mg、Si物质转化生成结晶性硅酸盐方面也起着重要的作用。

关键词: 铬铁矿, 酸浸, 氢氟酸, 过程强化

Abstract:

The production of chromium salt by acid leaching and decomposition of chromite shows a great application prospect because the process can avoid the production of hexavalent chromium [Cr(‍Ⅵ)]. Using hydrochloric acid as the acid-leaching agent can take advantage of the difference in solubility of metal ions in hydrochloric acid, making the process characterized by easy recovery of residual acid and chromium salts. However, it also makes the leaching efficiency of chromite leaching by hydrochloric acid low because of the dissolution equilibrium. In this paper, a new process study of hydrofluoric acid (HF) enhanced chromite leaching by hydrochloric acid is proposed to improve the chromite leaching process’s efficiency. Based on the previous work, this paper investigates the laws, kinetics, and process mechanism of HF-enhanced chromite hydrochloric acid leaching. The results show that HF can significantly enhance the leaching rate of Cr and Fe in chromite, which increases with the increase of HF dosage, while the leaching rate of Al and Mg shows a trend of increasing and then decreasing with the rise of HF dosage. The other crystalline silicates enter the slag phase. This finding provides a basis for selecting appropriate leaching conditions to better separate Cr from impurities such as Al and Mg in the leachate. Cr, Fe, Al and Mg leaching rates can reach about 92%, 94%, 17%, and 14%, respectively, at higher HF dosages. HF dosage not only influences the control steps of the kinetics of the chromite hydrochloric acid leaching process but also plays an essential role in promoting the conversion of Al, Mg and Si-containing substances in the leachate to crystalline silicates.

Key words: chromite, acid leaching process, hydrofluoric acid, process intensification

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