CN1310240A

CN1310240A - Method of utilizing beta-naphthol for eliminating Co in main and subsidiary zinc electrolyzing systems

Info

Publication number: CN1310240A
Application number: CN00113286A
Authority: CN
Inventors: 周春山; 蒋新宇; 王艳; 钟世安
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2000-02-25
Filing date: 2000-02-25
Publication date: 2001-08-29

Abstract

Oxidant is first used to oxidize Co2+ and Fe2+ into CO3+ and Fe3+ and Co3+ precipitant is then used to separate Co. The present invention needs no synthesis equipment and thus has low production cost; the chelate of Co3+ and alpha-NO-beta-NP has high stability and great reaction speed resulting in complete Co3+ precipitation, short precipitation period and easy-to-control reaction condition. In the high CO3+ density of 100-150 mg/L, the Co3+ precipitation rate may reach 99 %. The present invention may be used in the precipitating separation and recovery of Co from zinc sulfate electrolyte, lean Cd liquid, Co sludge pickler.

Description

Method for removing cobalt from main system and auxiliary system of electrolytic zinc by using β -naphthol

The invention relates to a hydrometallurgical process of zinc, in particular to a separation method of cobalt in zinc sulfate electrolyte, poor cadmium solution and cobalt slag pickling.

Adopts β -naphthol to remove cobalt, uses β -naphthol (β -NP) as raw material, and utilizes addition reaction to synthesize α -nitroso- β -naphthol (α -NO- β -NP), under the condition of a certain condition, the latter and Co are added³⁺Generating insoluble chelate to separate cobalt from the main components of zinc, cadmium, etc. in solution (Yangfang Xizao, Bantian Zhendamin, Yandao refining, resource と material, 1993,109(12):1039-3-1006). By adopting the method, the cobalt in the feed liquid can be reduced to a lower concentration so as to achieve deep purification. However, the method is only applied to zinc sulfate electrolyte after iron, copper and cadmium are removed, the reaction conditions are strict, and the method is still insufficient in the aspects of adaptability to high-amount cobalt separation, complete separation in the presence of a large amount of iron and the like.

The invention aims to provide a method for separating cobalt, which expands the application range of β -naphthol cobalt deposition, and is suitable for zinc electrolyte, poor cadmium solution and cobalt slag pickling solution.

The invention firstly adopts oxidant to mix low-valence Co²⁺、Fe²⁺First oxidized to high-valence Co³⁺、Fe³⁺Then adding a cobalt precipitation agent to realize the separation of cobalt, wherein the specific process conditions are as follows:

a>oxidation reaction: according to Co²⁺、Fe²⁺Adding an oxidant NaNO into the zinc sulfate solution₂The addition amount of the oxidant is properly excessive compared with the theoretical amount so as to ensure that the reaction is complete, and the pH value of the solution is 2.8-3.5; the oxidant may also be KMnO₄、MnO₂。

b, cobalt precipitation reaction, namely adjusting the pH value of the oxidized solution to 2.8-4.0 at the temperature of 30-75 ℃, and slowly adding a cobalt precipitation mixed solution (β -NP + NaNO) while stirring₂) After 15-20min, stirring for 15-20min at the temperature, wherein the adding amount is that the molar ratio of Co to α -NO- β -NP is 1: 3-4, directly generating a cobalt precipitation agent in a cobalt precipitation system, and adding NaNO into a dissolved β -NP solution₂Stirring until the cobalt precipitate agent α -NO- β -NP. is generated, and the oxidation reaction scheme is as follows: the cobalt precipitation reaction is as follows:

according to the stability of complex and the reaction kinetic principle, the preferential oxidation method is adopted to convert low-valence cobalt and iron into high-valence cobalt and iron ions, so that cobalt is generated more stably and more difficultly at a higher speedDissolved Co³⁺(α-NO-β-NP)₃Chelate of Fe³⁺Is easy to hydrolyze, thereby facilitating the separation.

The invention can be used for zinc sulfate electrolyte of main system of electrolytic zinc, and can be used for cobalt precipitation separation and cobalt recovery in poor cadmium solution and cobalt slag pickling solution.

The invention has the following advantages:

(1) cheap β -naphthol is used as a raw material, α -NO- β -NP is directly generated in a cobalt precipitation system, NO synthesis equipment is needed, and the production cost can be greatly saved;

(2) co is oxidized by adopting a preferential oxidation method or a method combining the preferential oxidation and the synchronous oxidation²⁺Can be oxidized into Co first³⁺The stability and reaction speed of the chelate formed by the chelate and α -NO- β -NP are both higher than those of Co²⁺The corresponding chelate is much larger, the cobalt precipitation is complete, particularly when the cobalt concentration is higher, such as 100-150 mg/L, the residual cobalt concentration can still be reduced to below 1mg/L, and the cobalt precipitation rate can reach 99%; the cobalt precipitation time is short (can be finished within 30 min), and the process can be shortened;

(3) the application range is wide, and the zinc-cadmium-free zinc-oxide electrolyte can be applied to zinc sulfate electrolyte, and can also be applied to poor cadmium solution with high cobalt content and cobalt slag pickling solution;

(4) because the chelate is stable and the dissociation degree is extremely low, the reaction conditions (such as pH and temperature control) are easy to control;

(5) in preferential oxidation, Fe²⁺Is oxidized into Fe³⁺When the pH value is more than 3, the catalyst can be completely hydrolyzed and removed first, so that the catalyst does not participate in the competition of the cobalt and the complexation reaction of α -NO- β -NP, and the catalyst is suitable for feed liquid with higher iron concentration.

Example (b):

1. separating cobalt in the poor cadmium solution of the electrolytic zinc system.

The poor cadmium solution is the filtrate obtained after copper and cadmium are recovered from copper and cadmium slag, wherein the cobalt and iron concentrations are higher and respectively reach 120mg/L and 250mg/L except zinc.

(1) Preparing a reactant:

A. oxidant solution: using NaNO₂The aqueous solution of (A) is used as an oxidizing agent;

B.chelating reagent mixture, adding NaNO into β -NP water solution₂And stirring to dissolve.

(2) Preferential oxidation reaction:

adding the oxidant A into the feed material in batches under stirring at the natural temperature (about 55 ℃) of the feed liquid and the pH value of 3-3.3, and continuing stirring for a plurality of minutes after the oxidant A is completely added so as to enable Co to be mixed for a plurality of minutes²⁺、Fe²⁺And (4) completely oxidizing.

(3) Removing cobalt by chelate reaction:

and (2) slowly adding the reactant B into the same material liquid under continuous stirring, and continuously stirring for 15-20min after the reagent is added.

(4) Removal and precipitation separation of excess β -NP or α -NO- β -NP

Then, in the step (3), activated carbon is added in an amount corresponding to the amount of β -NP or α -NO- β -NP remaining, and the mixture is stirred for 15 to 20 minutes to complete adsorption, and the feed solution is filtered to obtain Fe (OH)₃、Co(α-NO-β-NP)₃The precipitate is separated from the poor cadmium solution, and the cobalt precipitation rate reaches 99.5 percent.

Claims

1. The method of using β -naphthol to eliminate Co in main and auxiliary zinc electrolyzing system features that the present invention adopts oxidant to eliminate Co with low valence²⁺、Fe²⁺Oxidized to high-valence Co³⁺、Fe³⁺Then adding a cobalt precipitation agent to realize the separation of cobalt, wherein the specific process conditions are as follows:

a>oxidation reaction: according to Co²⁺、Fe²⁺Adding an oxidant NaNO into the zinc sulfate solution₂The addition amount of the oxidant is properly excessive compared with the theoretical amount so as to ensure that the reaction is complete, and the pH value of the solution is 2.8-3.5;

b>cobalt precipitation reaction, namely adding a cobalt precipitation mixed solution β -NP + NaNO into the oxidized solution₂The addition amount of β -NP is that the molar ratio of Co to α -NO- β -NP is 1: 3-4.

2. The method of claim 1, wherein: the oxidant may also be KMnO₄、MnO₂。

3. The method of claim 1, wherein the cobalt precipitating agent is directly generated in the cobalt precipitating system, NaNO is added into the dissolved β -NP solution₂Stirring until the cobalt precipitate is dissolved to generate α -NO- β -NP.

4. The method of claim 1, wherein: the invention can be used for the precipitation separation and cobalt recovery of cobalt in zinc sulfate electrolyte, poor cadmium solution and cobalt slag pickling solution of the main system of electrolytic zinc.