Preparation method for compact crystallographic form cobalt hydrate

The invention relates to a preparation method for a compact crystallographic form cobalt hydrate. The prior method has high requirements on the production equipment and process conditions, thereby not only increasing the production cost, but also hardly avoiding the oxidation of products in subsequent procedures such as filtering, washing, drying, and the like. The prior method has rigor reaction conditions and higher difficulty in the industrialized production. The preparation method comprises the following steps: taking cobalt salt solution as base solution, adding slightly alkaline substance into the base solution while stirring the solution, carrying out a precipitation reaction to form basic salt turbid solution of alpha-Co(OH)2; and then continuously injecting NaOH solution and protective agent solution into the turbid solution to replace the anions in the basic cobalt salt, regulating the pH value to convert alpha-Co(OH)2 into cerise beta-Co(OH)2, and obtaining the cobalt hydrate which is a compact crystallographic form particle. The preparation method well solves two problems of colloid formation prevention and oxidation inhibition and obtains the cerise cobalt hydrate crystals with good crystallinity. The preparation method has simple and easily-controlled reaction conditions and is suitable for the industrialized production.