The invention relates to the technical field of
sponge hafnium preparation, and provides a multistage gradient reaction furnace and method for
sponge hafnium preparation, and the reaction furnace comprises a
machine body, a storage cylinder, a reaction cavity, a preliminary reaction box, a cylinder body, a centrifugal mechanism and a heat
recovery module. The cylinder adopts a
permalloy magnetic conductive layer, an
yttrium-
zirconium lining, a permanent
magnet array and a steel shell multi-layer
composite structure, the permanent
magnet array forms a radial
magnetic field, the
magnetic field inhibits micro-turbulence of fused
magnesium chloride, the
oxygen diffusion coefficient is reduced, and migration of
oxygen to a
grain boundary is reduced; in a temperature environment of 800-1000 DEG C, under the synergistic effect of a low-
oxygen grain boundary environment and a thermal gradient effect,
hafnium grains grow to form uniformly distributed radioactive state crystals; in the reaction process, high-efficiency and high-purity
sponge hafnium preparation is realized through multi-stage gradient
temperature control of initial reaction at 600-800 DEG C,
grain growth at 800-1000 DEG C and melting separation at 1000-1100 DEG C in combination with vibration accelerated reaction and
centrifugal separation of by-products.