Abstract: In allusion to the problem that the grade of ultrafine spherical Ni powder was very low（only about 96%） prepared from nickel sulfate by liquid hydrogen reduction process，a combined process of pyro-and hydro-metallurgy was introduced in order to improve the grade of Ni powder.Firstly，mix the nickel sulfate with sodium hydroxide solution to prepare nickel hydroxide slurry at room temperature.Without washing and filtering，the slurry was put into the high-pressure reactor where the hydrogen reduction reaction happened in a suspended state.After the reaction，simi-finished Ni powder with about 96% was obtained through liquid solid separation.Then the secondary reduction was carried out in a hydrogen reduction furnace. Under the conditions of reduction temperature 400 ℃ and reduction time 2 h，the product′s mass fraction of Ni was over 99.5% and product′s particle size was less than 2.0 μm，which could meet requirements of performance indexes of diamond tools and cemented carbide industries.

Key words: nickel sulfate, hydrogen reduction, ultrafine spherical Ni powder