JPS596814B2 - Method for manufacturing vanadium compounds using molten iron alloy refining slag as raw material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for recovering vanadium from slag produced when refining a molten iron alloy such as hot metal in the presence of an alkali metal compound.

The slag that is the object of the present invention contains 10 to 60% alkali metal in the form of various alkali metal salts, and a method for recovering this as alkali metal carbonate-containing salt that can be used as a raw material for refining etc. There are several methods invented by the present inventors.

(JP-A-52-148498, JP-A No. 53-42200, JP-A No. 53-102213).

On the other hand, the slag contains 0.1 to 10% vanadium, which is successively concentrated in the circulating aqueous solution in the alkali metal carbonate recovery process.

As a method for recovering vanadium, a method invented by the present inventors involves extracting a part of the process circulating liquid containing concentrated vanadium outside the process, adjusting the pH to 4 to 8, and recovering the vanadium compound by precipitation (Japanese Patent Application Laid-open No. 53-8308), but
According to this method, a part of the process liquid containing the alkali metal compound is extracted outside the process, so the recovery rate of the alkali metal decreases, and a considerable amount of reducing substances such as 8203'- coexists, so the process solution must be removed before vanadium recovery. The problem was that the processing costs were high and the collection costs were high.

The present invention aims to provide an inexpensive vanadium recovery technique that does not reduce the recovery rate of alkali metal compounds due to vanadium recovery and minimizes the processing of coexisting substances.

The method for recovering vanadium from refined slag according to the present invention will be described in detail below.

Hot metal or other molten iron alloys are mixed with alkali metal compounds (
This will be explained below using soda carbonate as an example.

) in the presence of oxidative refining, Na 1 0-60%
, Si1-15%, P0.5-22%, SO. 1-5%
, (2) A slag containing 0.1 to 10% is obtained.

When this slag is crushed and dissolved in water, the water-soluble components in the slag are eluted into the water, and a slurry containing insoluble residues is obtained.

As the water used for dissolving the slag, in addition to ordinary industrial water, water containing Na, such as dust collection water used when volatile matter generated in the reaction vessel is collected by wet dust collection, can be used.

Most preferably, the mother liquor remaining when Na is recovered as a carbonate-containing salt in the latter step is circulated and used for dissolving the slag.

This process circulating water contains 1 to 20% Na carbonate-containing salt, which is 2 to 20 times the weight of the slag, preferably 3 to 20%.
When the slag is dissolved by using it 10 times more, 80% or more of Na and P are transferred to the aqueous solution.

When the pH of the solution is high, the proportion of Si transferred to the aqueous solution as water-soluble silicic acid increases, but if the pH of the solution is below 12, most of the Si becomes insoluble silicic acid and precipitates, so it must be separated from the solution. I can do it.

The pH of the solution is determined by the slag to solvent ratio, the type and concentration of carbonate-containing salts in the solvent, etc., but if necessary, the precipitation rate of S1 can be adjusted by adding weakly acidic substances such as carbon dioxide gas to adjust the pH. It is also possible to increase

The lower the pH, the more complete the precipitation of Si will be, but if the pH is less than 9, carbonate-containing salts of Na will also be precipitated, which is not desirable.

The behavior of S in a solution differs depending on the pH of the solution and oxidation conditions, but it is possible to separate most of the Si by precipitation.
In the H=12-9 range, air or 0 is added to the aqueous solution.

When an oxidizing substance such as gas is added, about 70% or more of S becomes insoluble and precipitates.

The precipitates of Si and S can be separated from the aqueous solution by filtration alone or in combination, but the precipitates are fine and filtration takes a long time.

After adjusting the pH in a slurry state in which insoluble residues coexist, and adding an oxidizing substance, precipitates of Si and S are filtered out together with the insoluble residues (this simplifies the filtration process).

When Si, S precipitates and undissolved residues are separated from the slag slurry, most of the Na, P and Si. An aqueous solution containing a portion of S is obtained.

When an alkali metal compound, most preferably Ca(OH)2, is added to this aqueous solution, P is precipitated as calcium phosphate and can be removed.

In this case, the liquid temperature is set to 20 to 80°C, and the P in the solution is 1 to 1.
When 2 equivalents of Ca (OH) 2 is added in the form of powder or milk of lime, more than 80% of the P can be removed.

By the above operations, Si and P in the aqueous solution are 80% or more, S
more than 70% is separated and removed.

S + 8 1 y? The solution obtained by separating the precipitate by filtration is a Na-containing liquid with few impurities, so this is led to a known carbonation tower, and after being brought into contact with CO gas, Na is precipitated as a Na carbonate-containing salt.

In this case, the factors that influence the recovery efficiency of carbonate-containing salts are the liquid temperature and Na concentration, and the lower the liquid temperature and the higher the Na concentration, the higher the recovery efficiency.

C.O. It is effective to increase the concentration of Na by evaporating a portion of the solution prior to the addition of Na in order to increase the recovery efficiency.

The precipitated Na carbonate-containing salt is separated and recovered from the solution by filtration by a conventional method or by evaporating the liquid to dryness.

The above operations do not necessarily need to be performed as described; for example, it is possible to precipitate P, adjust the pH to precipitate Si, and simultaneously filter these to improve filterability, or to It is also possible to separate it from the solution after precipitation.

The solution after filtering the Na carbonate-containing salt is returned to the slag dissolution process or carbonation process and recycled within the process.

During this circulation process, impurities and valuable elements such as V become concentrated in the liquid, but it is S that becomes concentrated and causes problems in refining.

Part of the circulating water can be blown out of the system, and water can be newly supplied from the outside to dilute the S in the solution.

There is also a method of removing S by applying a known ion exchange membrane method or submerged combustion method to a small portion of the circulating water.

If about 10% of the circulating water is subjected to reducing submerged combustion with an air ratio of 0.6 to 0.8 using propane gas or the like as a combustion aid, it is possible to keep S in the circulating water low.

By lowering the impurity concentration in the solution and thoroughly dehydrating the sodium carbonate-containing salt using a vacuum dehydrator or the like when filtering the Na carbonate-containing salt, it is possible to obtain a Na carbonate-containing salt with a small amount of impurity adhesion. Can be collected regularly.

The P and S contents of the recovered Na carbonate-containing salt were each 1% or less, and it was confirmed that there was no difference in the refining results even when the entire amount was used.

Vanadium concentrated in the circulating water can be recovered by taking out a part of the circulating water as described above and using known methods such as the method of JP-A-53-8308, the red cake method, and the ammonium polyvanadate method. As a result, part of the circulating water in the process is extracted and the pH is adjusted to a neutral or acidic range, so there is a loss of sodium because it cannot be recovered as a carbonate-containing salt, and 8203'-(S), which is concentrated in the circulating water like vanadium. It is difficult to economically recover vanadium due to the oxidation treatment, which accounts for more than half of the amount of vanadium.

On the other hand, it is not necessarily economical to apply the solvent extraction method, which is often used in the refining of non-ferrous metals, to the recovery of vanadium from refining slag.

That is, the solvents generally used for vanadium recovery are neutral, acidic, and basic (primary to tertiary amine) extraction reagents, and all of these are effective solvents in the acidic region.

Therefore, in order to take out a part of the process circulating water and recover vanadium by the solvent extraction method, it is necessary to make the pH of the extracted liquid acidic.
As with the method No. 08 or the red cake method, it often causes a loss of sodium and impairs economic efficiency.)

As is clear from Japanese Patent Publication No. 37-11205, trifatty monomethyl quaternary ammonium compound is an alkali JP.
4E is a solvent from which vanadium can be extracted, and the commonly used form is trifatty monomethyl quaternary ammonium compound in the form of chloride or sulfate.

As used herein, the term "trifatty monomethyl quaternary ammonium compound" refers to a quaternary ammonium compound having three 08-C1o aliphatic groups and one methyl group.

However, if this trifatty monomethyl quaternary ammonium compound in the chloride or sulfate form is used as it is as a solvent for recovering vanadium from process circulating water, the following problems arise.

That is, when a trifatty monomethyl quaternary ammonium compound, that is, a liquid anion exchanger is brought into contact with circulating water for the purpose of recovering vanadium from process circulating water, vanadium anions such as vanadate in the circulating water are converted to anions ( In this case, the vanadium is fixed in the trifatty monomethyl quaternary ammonium compound, while the anion is transferred to the circulating water.

For this reason, as vanadium is recovered, chlorine or sulfate ions gradually become concentrated in the process circulating water, and the former causes corrosion of equipment, while the latter causes S
This leads to undesirable situations such as increasing the content and causing problems in refining.

After much study, the present inventors have discovered a method for recovering vanadium using a carbonate of a trifatty monomethyl quaternary ammonium compound, which does not cause the problem of concentration of anions and does not cause loss of sodium. .

That is, a normally supplied trifatty monomethyl quaternary ammonium compound in the form of a chloride or sulfate is brought into contact with an aqueous solution containing a carbonate, an ammonium carbonate salt, ammonium hydroxide, etc. After converting to a quaternary ammonium compound, alkali I having a pH of about 9 to 13 (preferably 9 to 11)
J I'l Process Vanadium is extracted and fixed into trifatty monomethyl quaternary ammonium compound by contacting with circulating water.

On the other hand, by anion exchange, trifatty monomethyl 4
Carbonate ions liberated from class ammonium compounds move into the circulating water, but this circulating water already contains a large amount of carbonic acid-containing soda salt, and these newly added carbonate ions are different from the chlorine or sulfate ions mentioned above. na l-
It does not cause any hindrance to the IJum recovery process and equipment.

Since the process circulating liquid after vanadium extraction is alkaline, it can be used again to dissolve the slag, and the sodium recovery rate does not decrease at all.

The vanadium fixed with trifatty monomethyl quaternary ammonium compound is brought into contact with an aqueous stripping solution containing 0.1 to 2 monol/l of carbon salt, ammonium carbonate salt, ammonium hydroxide, etc., to reverse the extraction process described above. Stripping is performed by the reaction, and vanadium is transferred into the aqueous solution as vanadium anions, and carbonate ions are transferred as carbonate groups bonded to the trifatty monomethyl quaternary ammonium compound.

The carbonate trifatty monomethyl quaternary ammonium compound regenerated by stripping can be repeatedly used for the extraction of vanadium from the process circulating water.

On the other hand, vanadium strung in an aqueous solution is directly used to crystallize ammonium vanadate, or the vanadium compound is recovered using other conventional methods.

Silicon, phosphorus, various sulfur ions, etc. contained in the process circulating water are hardly extracted by the vanadium extraction solvent.

That is, according to the vanadium recovery method according to the present invention, vanadium can be extracted without (1) loss of sodium in the process circulating water.

■ Since the coexisting components contained in the process circulating water are not extracted, the vanadium compound recovery process is simplified.

■ In the process of recovering soda ash for refining from refining slag,
It does not contain components that cause problems such as chlorine or sulfate ions.

It has great benefits such as, completely solving the drawbacks of conventional methods and making it possible to recover vanadium extremely economically.

Example After oxidizing and refining hot metal using mainly soda carbonate as a slag-forming agent and removing impurities such as insoluble residues, silicon, and phosphorus from a solution of the resulting slag dissolved in water, Sodium carbonate was recovered using a prescribed method.

The process circulating water after soda ash recovery had the composition shown in Table 1.

The organic solvent phase used for extraction was 5 vol% trifatty monomethyl quaternary ammonium compound carbonate (commercial product Gcneral Mills Chemicals I
nc. Manufactured by Aliquat 336 ((R3NCH3)”
CIl-(R-C8-C1o)] previously converted to carbonate form 5 vol% decanol and 90 vol%
Consists of kegushin.

The ratio of the process circulation aqueous phase to the organic phase was 1.

After adjusting the pH of the process circulating liquid to 10, three-stage extraction was performed and the results are shown in Table 1.

When this vanadium-containing organic phase was stripped with 1.5 mol/l ammonium carbonate, a back extraction rate of 88% for vanadium was obtained.

Claims (1)

[Claims] 1 A method for recovering vanadium in an aqueous solution of slag using slag produced when refining a molten iron alloy in the presence of an alkali metal compound as a raw material, and in which trifatty monomethyl quaternary ammonium compound is preliminarily converted into carbonate. After converting the vanadium into a quaternary ammonium compound, the vanadium is extracted in an alkaline region, and this is back-extracted with an alkaline aqueous solution containing ammonium carbonate to separate the vanadium compound, and the regenerated trifatty monomethyl quaternary ammonium A method for producing a vanadium compound using molten iron alloy refining slag as a raw material, characterized by repeatedly using carbonate of the compound for extraction of vanadium.