| 摘要 |
PROBLEM TO BE SOLVED: To provide superfine powder having a specified mean grain size and high in quality while maintaining the high production efficiency by introducing a raw material gas of which the partial pressure of a nickel chloride gas is specified, and reducing the nickel chloride gas by hydrogen in this reducing furnace while allowing the nickel chloride gas to flow with its space velocity in a specified range. SOLUTION: The partial pressure of the nickel chloride gas is set to 0.2 to 0.7, and the space velocity(SV) is set to 0.02 to 0.07 sec-1, and the mean grain size of the obtained superfine Ni powder is 0.1 to 0.4μm. The reducing reaction in a reducing furnace 10 is achieved in a reaction part 12 at the temperature of 950-1150 deg.C. When a raw material gas of 0.2-0.7 in the partial pressure of the nickel chloride gas is introduced in the reducing furnace 10 from a raw material discharge nozzle 30, the nickel chloride gas is immediately brought into contact with hydrogen to form a Ni core and made to grow. The Ni is rapidly cooled by the inert gas introduced from a cooling gas introduction pipe 11 provided on a lower part of the reducing furnace 10, and its growth is stopped. The generated superfine Ni powder is then transferred to a separation and recovery process.
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