Facile preparation of highly pure KF-ZrF4 molten salt

The preparation of highly pure KF-ZrF 4 (FKZr) molten salt, a potential secondary coolant in molten salt reactors, was realized simply by heating a mixture of (NH 4 ) 2 ZrF 6 and KF. X-ray diffraction analysis indicated that the FKZr molten salt was mainly composed of KZrF 5 and K 2 ZrF 6 . The melting point of the prepared FKZr molten salt was 420–422 °C under these conditions. The contents of all metal impurities were lower than 20 ppm, and the content of oxygen was lower than 400 ppm. This one-step protocol avoids the need for a tedious procedure to prepare ZrF 4 and for an additional purification process to remove oxide impurities, and is therefore a convenient, efficient and economic preparation method for high-purity FKZr molten salt.