JPS6259055B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering vanadium from vanadium-containing water.

Vanadium is patronite, vanadium mica,
It is contained in ores such as carnotite and katulinite, or in heavy oil. The recovery method is to bake vanadium raw minerals together with common salt at about 800℃ to form sodium vanadate, leaching it with water and dilute acid, and adding sulfuric acid to precipitate it as oxide ore. If this precipitate contains 80% or more of vanadium pentoxide, it can be used industrially as vanadium pentoxide, but since most of it contains impurities such as Na ₂ O and CaO, this precipitate must be redissolved in a sodium carbonate solution. Then, ammonium chloride is added in a pentavalent state to precipitate ammonium metavanadate, which is centrifuged, washed with water, and dried to obtain a product. This process produces a large amount of vanadate-containing wastewater. Furthermore, the exhaust gas cleaning liquid from heavy oil combustion furnaces also contains vanadate.

Conventionally, vanadate in these wastewaters has been recovered by a coagulation-sedimentation method using iron salts, etc., but wastewater contains coexisting metal ions in addition to vanadate ions, and as a result, separation of vanadium is insufficient. It was hot. Furthermore, from the standpoint of pollution prevention, it is necessary to further reduce the vanadium content in wastewater.

As a method for achieving these objectives, for example, a method of adsorbing vanadate to CI-type strongly basic ion exchange resin and then eluating and regenerating it with a 10% sodium hydroxide solution (Japanese Patent Laid-Open No. 48-97784)
(see specification) has been proposed. However, this method has drawbacks such as a low elution rate and a significant decrease in vanadate adsorption capacity due to the presence of coexisting anions.

The present inventors solved these drawbacks and conducted extensive studies on a method for efficiently adsorbing and recovering vanadium from vanadium-containing wastewater, and as a result, they completed the present invention.

The present invention is a method for recovering vanadium from vanadium-containing water, which is characterized by contacting vanadium-containing water with titanic acid at a pH of 8 or lower to adsorb vanadium, and then eluting the adsorbed vanadium with an alkaline aqueous solution.

Vanadium-containing water refers to an aqueous solution containing various vanadium compounds. Vanadate ions in aqueous solutions are usually orthovanadate ions (VO ₄ ^3- ), pyrovanadate ions (V ₂ O ₇ ^4- ), and metavanadate ions (VO ₃ ^- ).
It exists in the form of complex ions as various isopolyic acid ions depending on the pH of each. In addition, vanadium is known to form various complex ions with oxygen atoms, hydroxyl groups, chlorine atoms, cyano groups, carbonyl groups, etc., and vanadium can also be recovered from water containing these vanadium complex ions by the method of the present invention. can do. The present invention is of particular industrial importance when recovering vanadium from the wastewater obtained during the treatment of the vanadium raw material mineral and from the exhaust gas cleaning liquid of a heavy oil combustion furnace. Note that a small amount of water-soluble organic substances such as acetic acid, acetic acid ester, alcohols, glycols, etc. may coexist in the vanadium-containing water, and the adsorption and elution of vanadium will not be significantly hindered by this.

In the present invention, titanic acid is hydrous titanium oxide represented by the chemical formula TiO ₂ .nH ₂ O, where n =
It is preferable to use one with a value of 0.2 to 2.0. This titanic acid is produced by heating and hydrolyzing an aqueous solution of titanium sulfate or titanium tetrachloride, or by adding a base to neutralize the aqueous solution, washing the resulting solid content with water, separating it, and then drying it. can get. This titanic acid can also be obtained by hydrolyzing a titanium alkoxide in water, washing the resulting solid with water, separating it, and then drying it. Since the titanic acid obtained by these methods is generally a powder with a particle size of several microns to several tens of microns, it is difficult to use it in a packed column system. In order to enable use in a packed column system, it is necessary to granulate titanate powder to a particle size of several hundred microns or more, but in order for the resulting granules to be used for the purpose of the present invention, requires acid and alkali resistance and sufficient surface area. A titanic acid granule that satisfies these conditions is, for example, anatase type or amorphous titanic acid, or a mixture thereof, sulfuric acid, preferably concentrated sulfuric acid, and water as additives.
Preferably 1 to 20 parts and 20 parts per 100 parts, respectively.
After adding at a ratio of ~100 parts, kneading, and granulating,
Titanic acid granules obtained by heat treatment at a temperature of 100 to 400°C are preferred.

When implementing the method of the present invention, titanic acid is introduced into the vanadium-containing wastewater to adsorb vanadium using a slurry method, and then eluted with an alkaline aqueous solution, and titanic acid granules are packed in a packed column. , a method is used in which the vanadium-containing wastewater is continuously passed through the titanate granules to adsorb vanadium, and then an aqueous alkali solution is passed through the titanic acid granules to elute the vanadium.
In both methods, where the latter packed column method is preferred, the vanadium-containing wastewater during the adsorption operation must have a pH of 8 or less, preferably adjusted to PH4 or less. When the pH exceeds 8, the adsorption amount of vanadium to titanic acid decreases significantly. In the case of a packed column system, the liquid passing rate during adsorption is preferably in the range of SV (space velocity) from 2 to 20. Furthermore, various alkaline aqueous solutions can be used as the alkaline aqueous solution used in the elution operation, but a 0.5-2.0N caustic soda aqueous solution is particularly preferred. The liquid passing rate during the elution operation is preferably in the range of SV 1 to 10.

According to the method of the present invention, it is possible to selectively adsorb vanadium-containing ions, particularly vanadate ions, from among various coexisting metal ions, and unlike commercially available anion exchange resins, it is hardly affected by coexisting anions, Furthermore, the dissolution rate is extremely high.

Parts in the following examples are parts by weight.

Example Specific surface area 215 m ² /g with particle size 10-200μ
5 parts of concentrated sulfuric acid and 60 parts of water were added to 100 parts of anatase-type titanic acid, thoroughly kneaded in a miller, and then passed through a screen with a diameter of 0.5 mm in a screw-type extrusion granulator to form particles with a length of 3 to 3 mm. 6mm and particle size
Make a molded product of 0.5mmφ. Next, this molded product was heated to 110
After drying in hot air at 300°C for 16 hours, granular titanic acid granules are obtained by firing at 300°C for 3 hours. This titanic acid granule has a packing density of 1.0 g/cc and a specific surface area of 180 m ² /g, and has sufficient strength even in a 1N sulfuric acid aqueous solution and a 1N caustic soda aqueous solution.

The granules thus obtained are packed into an acrylic column with an inner diameter of 50 mmφ at a bed height of 500 mm. On the other hand, using ammonium metavanadate, calcium chloride and sodium sulfate,
A sample wastewater containing 50ppm of vanadate ions and 500ppm of sulfate ions was prepared, and the PH of this wastewater was determined.
are adjusted to 7 and 3 with sulfuric acid, respectively. Each wastewater is passed through the column in a downward flow at a flow rate of SV=5, and vanadate ions are adsorbed onto the granules until they reach saturation. At this time, the adsorption amount of vanadate ion is calculated as vanadium per ml of granules at pH 7.
It was 20 mg, and 50 mg at PH3. Next, a 1N caustic soda aqueous solution was passed through the granules that had adsorbed vanadate ions in a downward flow of SV = 2 for 1 hour to elute the vanadate ions, and an elution rate of 98% or more was obtained for each. .

For comparison, a similar experiment was conducted using a commercially available gel-type quaternary ammonium salt-type strongly basic anion exchange resin (ion exchange capacity 1.3 milliequivalents/ml) instead of the titanic acid granules. The adsorption amount of vanadate per ml of ion exchange resin was less than 1/10 of that of titanic acid granules at any pH.

Claims (1)

[Claims] 1. A method for recovering vanadium from vanadium-containing water, which comprises contacting vanadium-containing water with titanic acid at a pH of 8 or less to adsorb vanadium, and then eluting the adsorbed vanadium with an aqueous alkaline solution. . 2. The titanic acid is titanic acid granules obtained by kneading anatase-type and/or amorphous titanic acid with sulfuric acid and water, granulating it, and then heat-treating it at a temperature of 100 to 400°C. and
A method according to claim 1.