NEUTRALIZATION METHOD AND NEUTRALIZATION PLANT

摘要

The purpose of the present invention is to provide a method capable of improving the filterability in separating a zinc sulfide produced by applying sulfurization treatment to a post-neutralization solution containing zinc together with nickel and cobalt in a dezincification step, and of prolonging a service life of a filter cloth, in a hydrometallurgical process for nickel oxide ore. The method comprises a neutralization reaction step of neutralizing leachate in a neutralization tank (11); a separation step of separating neutralized slurry into a neutralized sediment and a post-neutralization solution by adding flocculant to the neutralized slurry; a measuring step of measuring the viscosity of the post-neutralization solution; a temporarily storing step of temporarily storing the post-neutralization solution in a storage tank; and a transfer step of transferring the stored post-neutralization solution to a dezincification reaction tank (31) used in a dezincification step S4 subsequent to a neutralization step S3. When the measured viscosity of the post-neutralization solution is higher than 0.10 sec/cm 2 ·mL that is the time required for the post-neutralization solution of 50 mL to pass through a membrane filter having a mesh opening size of 0.45 µm, a flow rate of the post-neutralization solution to be transferred to the dezincification reaction tank (31) is controlled and the post-neutralization solution is circulated by returning back a predetermined rate of the post-neutralization solution to the neutralization reaction tank (11).