Experimental Investigation on Preparation of NaMgF3 and MgF2 from the Leaching Solution of SPL

Generally, there is a large amount of sodium fluoride in the spent potlining of aluminum electrolysis (SPL), which is a high-value fluorine resource. Therefore, recycling the fluorine resource from SPL is of profound significance, which not only saves the primary fluorine resource but also reduces energy consumption and carbon emissions. In this paper, co-precipitation method for the preparation of NaMgF3 and MgF2 was explored by using the leaching solution of SPL as raw material and magnesium sulfate as reagent. The results showed that the decisive factor for the type of product was the molar ratio of magnesium ion to fluorion (M/F) rather than the reaction temperature and holding time. When M/F is < 0.33, the product was mainly NaMgF3. When M/F increased further to 0.33-0.81, MgF2 was gradually produced, and the product was a mixture of NaMgF3 and MgF2. When M/F exceeded 0.81, the product was mainly MgF2.

Automated summary

In this paper, the co-precipitation method was used to prepare NaMgF3 and MgF2 using the leaching solution of SPL and magnesium sulfate as raw materials. The molar ratio of magnesium ion to fluorion (M/F) was found to be the decisive factor for the type of product. NaMgF3 was mainly produced when M/F < 0.33, while MgF2 gradually formed when M/F increased to 0.33-0.81, and the product became a mixture of NaMgF3 and MgF2. When M/F exceeded 0.81, MgF2 was the main product.