JPS60243236A - Method for removing magnesium during refining of zinc - Google Patents

Abstract

PURPOSE:To remove magnesium economically and efficiently by recovering sulfuric acid from tail liq. contg. magnesium produced by the electrolysis of zinc by diffusion dialysis and by adding a neutralizing agent to precipitate zinc. CONSTITUTION:Tail liq. contg. magnesium produced by the electrolysis of zinc is fed on one side of a membrane for diffusion dialysis, and at the same time, water is fed on the other side in counter-current to recover sulfuric acid from the tail liq. by selective dialysis. The tail liq. is then neutralized to 6-7pH by adding a neutralizing agent such as slaked lime to precipitate zinc hydroxide. This zinc hydroxide is dissolved in the recovered sulfuric acid and returned to a main electrolyzing stage. Thus, zinc free from magnesium is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for removing magnesium, which is an impurity, from a zinc electrolyte.

[Prior art]

When the concentration of magnesium in the electrolyte increases, especially in the electrolyte in the hydrometallurgy of zinc, the viscosity of the electrolyte increases, causing problems such as a decrease in the pumping capacity, as well as increasing the electric power consumption for zinc electrolysis. This results in economically disadvantageous operations.

The following three methods are conventionally known as methods for removing magnesium in zinc electrolytic smelting.

(11 A method in which a part of the cleaning process liquid in zinc hydrometallurgy is bloodletted, the bloodletting is evaporated and recovered as crystals of zinc sulfate, and magnesium is contained in the crystals and removed.

(2) Part of the electrolyzed tail fluid is bloodletted, the blood is electrolyzed to recover zinc metal, and the tail fluid after electrolysis is further neutralized to precipitate and recover the remaining zinc, which contains magnesium. How to contain and remove.

(3) A method of selectively removing magnesium in the raw ore by leaching M family sulfide ore with 1 μl sulfuric acid before roasting.・There are many training centers, but this method has the following runner-up points.

That is, since the zinc concentration is lower than that of an aqueous electrolyte, the current efficiency in electrolyzing blood is low, and the equipment costs required for electrolysis are high, and the running costs such as personnel costs are high. Furthermore, there are many neutralizing agents for recovering residual zinc in the tail fluid after electrolysis of bloodletting.

[Purpose of the invention]

It is an object of the present invention to overcome the drawbacks of the conventional methods described above and to provide a method for economically and efficiently removing magnesium from a zinc electrolyte.

[Summary of the invention]

The present invention involves filtering the zinc electrolytic tailings containing magnesium from an aqueous electrolysis process and flowing it to one side of a diffusion dialysis membrane.
At the same time, water is allowed to flow countercurrently to the other side of the diffusion dialysis membrane to recover the sulfuric acid content in the electrolytic tailing liquid by selectively dialyzing it. A neutralizing agent such as calcium carbonate or slaked lime is added to the electrolytic tailing liquid to make the volume 6 or 7, and the zinc contained in the electrolytic tailing liquid is precipitated as zinc hydroxide, which is then filtered to separate solid and liquid. The zinc hydroxide precipitate is characterized in that it is redissolved in the previously recovered sulfuric acid aqueous solution and then returned to the aqueous electrolysis process. Further, slaked lime is added to the filtrate from which the zinc hydroxide precipitate has been removed to make the volume 8 to 9, and the magnesium contained in the carcass filtrate is precipitated as hydroxide, and the mixture is filtered to separate solid and liquid. The F solution is to be returned to the main electrolysis and dissolution process. The obtained magnesium hydroxide precipitate may be disposed of as is, or it may be smoldered to form magnesium oxide and used as a raw material for ceramics.

The method of the present invention is characterized in that the sulfuric acid diffusion dialysis technique is applied to the removal of magnesium from a zinc electrolyte. That is, in the method of the present invention, sulfuric acid is recovered by a slow diffusion dialysis method instead of electrolysis, which has a low zinc recovery efficiency, and after neutralization recovers zinc as a precipitate of zinc hydroxide, the precipitate is removed using the previously recovered sulfuric acid. By redissolving the zinc and returning it to the aqueous electrolysis process), it is possible to recover almost the entire amount of zinc contained in the electrolyzed tail fluid without electrolysis and with a very small amount of neutralizing agent. Moreover, it is not necessary to newly use sulfuric acid to redissolve the zinc hydroxide precipitate, and the magnesium removal method is much more economical and industrially advantageous than the conventional method for removing magnesium from zinc hydroxide precipitates. This is a removal method.

〔Example〕

Next, examples of the present invention will be shown.

Example 1゜Zn 50.4 r/4' Mg 11.5 f/19
Ca O, 2rA output S Oa 154. The electrolytic tailing solution having a composition of Ot/At was passed through a commercially available diffusion dialysis device with an effective area of 0.8 to be dialyzed. The dialysis conditions were as shown in Table 1 below.

Table 1 The results of the dialysis are shown in Table 2 below.

Sulfuric acid recovery rate 82.5chi Next, slaked lime milk was added to the treated tail liquid, - was set to Zl,
The generated precipitate was filtered and removed.

Filtrate OZn concentration is 0.5 t/lv Mg concentration is al
t/l te @ In other words, the precipitate formation rate of zn is 9
The precipitate formation rate of a7%Mg was 6.9%.

Slaked lime milk was added to the filtrate to make the volume 90, and the formed precipitate was filtered and removed. Zn8 degree of F solution is 0.
01 f/lp Mg concentration was 5.9 t/l.

Example 2 Zn 50.3? /At Mg 19.3 S'/4
An electrolytic tailing solution having a composition of Ca 2 r/z + & 5 O 4150, 4 f/L was passed through the same diffusion dialysis apparatus as in Example 1 and dialyzed.

The dialysis conditions are as shown in Table 6 below.

The results of the dialysis are shown in Table 4 below.

Sulfuric acid recovery rate: 71.2ts Next, the treated tail liquid was neutralized in two stages in the same manner as disclosed in Example 1, and zn and Mlf were each recovered as hydroxide. By one-stage neutralization and filtration at pH 7.6, znO
, 1 μ (precipitate formation rate 992 μ), Mg 14.7
f/L (precipitate production rate: 89%) OF liquid t' was obtained. Next, during the second stage of neutralization and filtration at pH 5, ZnO,
00t/l+Mg 7.2 f/L no F liquid was obtained.

〔Effect of the invention〕

According to the method for removing magnesium according to the present invention, the loss of zinc and sulfuric acid in the electrolytic tailings can be minimized, Mg in the electrolyte can be efficiently removed, and troubles caused by magnesium during the electrolytic process of this system can be solved. This is a useful method for moss.

Agent: Patent Attorney Sanro Kimura

Claims (1)

[Claims] A zinc electrolytic tailing liquid containing magnesium is flowed on one side of the diffusion dialysis membrane, and at the same time, water is flowed countercurrently to the other side of the diffusion dialysis membrane in a countercurrent to the flow of the electrolytic tailing liquid, so that sulfuric acid in the electrolytic tailing liquid is After recovering the tail liquid by selectively dialyzing it, add a pH additive to adjust - to 6 to 7 to precipitate zinc, and remove the zinc precipitate with the previously recovered sulfuric acid aqueous solution. A method for removing magnesium in zinc smelting, which is characterized by dissolving it and returning it to the fundamental electrolytic process.