The hydrometallurgical process for a
nickel oxide ore comprising a step (1) for obtaining an
aqueous solution of crude
nickel sulfate by
High Pressure Acid Leach of a
nickel oxide ore; a step (2) for obtaining a
zinc free final solution formed; a step (3) for obtaining a waste solution; and a step (4) for scrubbing a
hydrogen sulfide gas in
exhaust gas, wherein utilization efficiency of
hydrogen sulfide gas is enhanced while maintaining nickel
recovery rate.It is characterized in that at least one kind of the following operations (a) to (d) is adopted.(a) to adjust total volume (m3) of the sulfurization reactor (B) in the above step (3), at a ratio of 0.2 to 0.9, relative to input
mass (kg / h) of nickel to be introduced;(b) to evaporate, under negative pressure,
slurry in the above step (3), and to add
hydrogen sulfide gas recovered to the above step (3);(c) to reuse
exhaust gas from the sulfurization reactor in the above step (3), and add it to the step (2); and(d) to subject the waste solution in the above step (3) and
exhaust gas in the above step (4) to countercurrent contact, then to introduce the exhaust gas to the
scrubber again and to charge waste solution from the
scrubber into the sulfurization reactor in the step (3).