Neutralization method and neutralization plant

Patent metadata

Field	Value
Publication number	US-9752211-B2
Application number	US-201314382737-A
Country	US
Kind code	B2
Filing date	Mar 1, 2013
Priority date	Mar 6, 2012
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

A method for 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 in a hydrometallurgical process for nickel oxide ore. The method includes a neutralization reaction step of neutralizing leachate in a neutralization tank, 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 step of 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 used in a dezincification step subsequent to a neutralization step.

First claim

The invention claimed is:

1. A neutralization method used in a neutralization step of neutralizing leachate produced by leaching nickel oxide ore, and producing neutralized sediment containing impurities and a post-neutralization solution containing zinc together with nickel and cobalt, in a hydrometallurgy process for nickel oxide ore, the method comprising:
a neutralization reaction step of neutralizing the leachate in a neutralization reaction tank;
a separation step of separating neutralized slurry into neutralized sediment and the post-neutralization solution by adding flocculant to the slurry;
a viscosity measuring step of measuring the viscosity of the post-neutralization solution produced through the separation step;
a storing step of temporarily storing the post-neutralization solution in a storage tank; and
a flow-feeding step of transferring the stored post-neutralization solution to a dezincification reaction tank used in a dezincification step subsequent to the neutralization step,
wherein in the flow-feeding step, when the post-neutralization solution has a viscosity, as measured in the viscosity measuring step such that the rate for passing 50 mL of the post-neutralization solution through a membrane filter having a mesh opening size of 0.45 μm, that is higher than 0.10 sec/cm 2 ·mL, a flow rate of the post-neutralization solution to be transferred to the dezincification reaction tank 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,
and when the viscosity of the post-neutralization solution measured in the viscosity measuring step is higher than 0.10 sec/cm 2 ·mL, a flow rate of the post-neutralization solution to be transferred to the dezincification reaction tank used in the dezincification step is set to 60 to 80% for the total flow rate, and a flow rate of the post-neutralization solution to be circulated by returning back the post-neutralization solution to the neutralization reaction tank is set to 20 to 40% for the total flow rate.

2. The neutralization method according to claim 1 , wherein in the flow-feeding step, when the post-neutralization solution is circulated by returning back the predetermined rate of the post-neutralization solution to the neutralization reaction tank, the flocculant is not added in the separation step.

3. The neutralization method according to claim 1 , wherein the storage tank has a capacity corresponding to an amount of storage of more than 3 hours with respect to the flow rate of the post-neutralization solution.

4. The neutralization method according to claim 1 , wherein the hydrometallurgy process for nickel oxide ore further comprises:
a leaching step of leaching slurry of the nickel oxide ore, under high temperature and high pressure, by adding sulfuric acid to the slurry of the nickel oxide ore;
a solid-liquid separating step of separating residue while multistage cleaning the leached slurry to produce leachate containing impurity elements together with nickel and cobalt;
a neutralization step of separating the neutralized sediment containing the impurity elements by controlling pH of the leachate to produce the post-neutralization solution containing zinc together with nickel and cobalt;
a dezincification step of producing a zinc sulfide by applying sulfurization treatment to the post-neutralization solution and separating the zinc sulfide to produce a mother liquid for nickel recovery containing nickel and cobalt; and
a nickel recovery step of producing a mixed sulfide containing nickel and cobalt by applying sulfurization treatment to the mother liquid for nickel recovery.

5. The neutralization method according to claim 4 , wherein the neutralized sediment separated in the neutralization step is repeatedly added in multistage cleaning in the solid-liquid separating step.

Assignees

• Sumitomo Metal Mining Co

Inventors

• Mitsui Hiroyuki
• Nakai Osamu
• Matsubara Satoshi

Classifications

• C22B23/0461 Primary

  by chemical methods · CPC title

• Y02P10/234

  Cross-Sectional Technologies · mapped topic

• C22B3/04

  by leaching (C22B3/18 takes precedence) · CPC title

• C22B23/0423

  Halogenated acids or salts thereof · CPC title

• Y02P10/20

  Recycling · CPC title