2 results about "Oxalate crystals" patented technology

This application provides a method for deep removal of calcium impurities from scandium oxide, belonging to the field of rare earth metal oxide purification. The method includes: dissolving scandium oxide raw material containing calcium impurities to obtain a calcium-containing scandium solution; adding a pH adjuster to the calcium-containing scandium solution to obtain a first scandium solution; reacting the first scandium solution with phosphoric acid and / or phosphate to obtain a second scandium solution and solid calcium phosphate; reacting the second scandium solution with a complexing agent to obtain a third scandium solution; reacting the third scandium solution with oxalic acid and / or sodium oxalate to obtain scandium oxalate crystals and a calcium complex solution; adding a strong acid solution to the calcium complex solution; and calcining the scandium oxalate crystals to obtain scandium oxide. Through calcium phosphate precipitation-complexation-crystallization, not only can calcium impurities be deeply removed from scandium oxide products, but impurities such as iron, titanium, and zirconium can also be removed, resulting in scandium oxide products with a purity of over 99.99%.

A method for preparing ferrous oxalate includes: dissolving an iron source and performing a reduction operation to obtain a first solution; adding a first liquid oxalic acid to the first solution and mixing and reacting to obtain a second solution; adding solid oxalic acid to the second solution and mixing and reacting to obtain a third solution containing a first reaction product; and removing impurities from the first reaction product to obtain ferrous oxalate. The ferrous oxalate has particle sizes including D10, D50, and D90, and its uniformity coefficient is (D90-D10) / D50, satisfying: 20μm≤D50≤60μm, 1.8≤(D90-D10) / D50≤8. This method can prepare both small- and large-particle-size ferrous oxalate, thus broadening the particle size range of ferrous oxalate crystals.