The invention discloses a method for preparing electronic-grade 
nickel sulfate from 
nickel powder, a 
crystallization device and a control method of the 
crystallization device, and relates to the technical field of non-
ferrous metal hydrometallurgy. The method comprises the steps of oxidation, cooling, acid leaching, 
copper removal, acid adjustment, concentration, cooling 
crystallization, 
drying and screening, and secondary leaching, and is characterized in that in the oxidation step, the temperature of 
nickel powder in a calcining furnace is controlled to be 400-700 DEG C, the use amount of 
compressed air for each 
kilogram of nickel 
powder is 1-5 m3, and the reaction is carried out for 1.0-2.5 hours; the acid leaching comprises the following steps: putting the cooled 
nickel oxide in a reactor, controlling the temperature to be 45-70 DEG C, adding dilute 
sulfuric acid to control the pH value to be 0.5-1.5, and reacting for 1-3 hours. The invention also provides a crystallization device and a control method of the crystallization device. According to the method, 
metal nickel can be oxidized into 
divalent nickel oxide, 
hydrogen cannot be released when acid is added for 
dissolution, a large number of oxidizing agents do not need to be additionally added, new 
impurity ions are not added in the process, the nickel 
ion concentration is relatively improved, and nickel 
sulfate crystal particles are uniform.