JP3144906B2 - Method for removing fluorine ions from zinc electrolyte - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adsorbing and removing fluorine ions in a zinc electrolyte using a hydrolysis product of titanyl sulfate dihydrate.

[0002]

2. Description of the Related Art Generally, in zinc refining, zinc ore obtained by roasting zinc sulfide concentrate or the like is treated in a melting tank, thickener, cleaning tank, or the like, and then treated in a cathode plate in an electrolytic cell. After zinc is deposited on the top and stripped off, it is melted and subjected to a process such as casting.

As the processing step in the electrolytic cell in the zinc refining is continued, fluorine ions are gradually accumulated in the zinc electrolyte, and the fluorine ion concentration increases. Under the influence of the fluorine ions, the surface of the cathode-side aluminum electrode was corroded. In an extreme case, a hole was formed, and the deposited zinc could not be separated from the electrode, and the electrode had to be discarded. Therefore, a fluorine ion removing method for maintaining a constant fluorine ion concentration in the zinc electrolyte is required.

Conventionally, when the concentration of fluorine ions in a zinc electrolyte becomes high, a part of the zinc electrolyte is extracted, and a new zinc electrolyte is replenished and diluted to maintain a constant fluorine ion concentration. I was Alternatively, raw materials are blended so as to lower the concentration of fluorine ions in the raw ore, and the reduction of the concentration of fluorine ions in the electrolyte has been awaited.

However, discarding the zinc electrolyte is a loss of zinc, which is costly.
In addition, there is a problem that a burden is imposed on wastewater treatment.In addition, when reducing the fluorine ion concentration from the raw material, it takes time until the fluorine ion concentration decreases, the cathode electrode is corroded by fluorine, and zinc is reduced. There is a problem that peeling off from the electrode becomes difficult, so that much labor is required for peeling off from the cathode electrode.

An object of the present invention is to provide a method capable of efficiently removing fluorine ions in a zinc electrolyte without discarding the zinc electrolyte.

[0006]

According to the method of the present invention, titanyl sulfate dihydrate is added to a zinc electrolytic solution, and alkali p is added.
An H adjuster is added to adjust the pH to preferably in the range of 2.1 to 4.2 to generate a hydrolysis product and to adsorb and remove fluorine ions in the electrolytic solution. It is a solution to the point.

As described above, the present invention is based on the finding that the hydrolysis product obtained by adding titanyl sulfate dihydrate to a zinc electrolyte and then adjusting the pH with an alkaline pH adjuster adsorbs fluorine ions. It was completed based on

In the present invention, any alkaline solution can be used as the alkaline pH adjuster, but it is preferable to use an aqueous zinc oxide solution in order to prevent contamination of the zinc electrolyte. Then, the pH is preferably adjusted to a range of 2.1 to 4.2 with these alkaline pH adjusters. pH
If the pH is less than 2.1, no hydrolysis product is produced, and if the pH exceeds 4.2, the form of the precipitate is different and fluorine ions are not adsorbed. In the present invention, the reaction temperature during mixing may be room temperature or may be heated. Heating at 20 to 60 ° C. is preferable for accelerating the hydrolysis reaction.

The amount of titanyl sulfate dihydrate added is appropriately determined according to the zinc concentration in the zinc electrolyte, and Ti due to the addition is recovered as a hydrolysis product and does not remain in the electrolyte.

[0010] The hydrolyzate to which the fluorine ions are adsorbed is then coagulated in a precipitate using a coagulant and filtered to separate the fluorine ions from the electrolytic solution.
Hereinafter, examples will be described.

[0011]

EXAMPLES Zinc electrolyte (zinc concentration 160 g / l) 500
ml of titanyl sulfate dihydrate (5 g / l),
Dissolved. Then, an aqueous zinc oxide solution was added, and the pH value was changed by changing the amount thereof, thereby producing a hydrolysis product. After stirring at 65 ° C. for 1 hour, a flocculant was added,
After standing, the hydrolysis product was filtered. Table 1 shows the results.

[0011]

[0012]

According to the present invention as described above, titanyl sulfate · 2 is contained in a zinc electrolyte having a high fluorine ion concentration.
By adding water salt, fluorine ions can be adsorbed and removed from the hydrolysis product, so that the electrolyte can be reused without discarding the electrolyte, without loss of zinc, and for wastewater treatment. A simple method for removing fluoride ions that does not require any burden and that does not select any ore,
Also, contamination by Ti does not occur even by the addition of titanyl sulfate dihydrate.

Claims (2)

(57) [Claims] 1. A method in which titanyl sulfate dihydrate is added to a zinc electrolytic solution, an alkaline pH adjuster is added to generate a hydrolysis product, and fluorine ions in the electrolytic solution are adsorbed and removed. Method for removing fluorine ions from zinc electrolyte. 2. The pH is adjusted to 2.1 to 2.1 with an alkali adjuster.
4. The method of claim 1 wherein the adjustment is in the range of 4.2.