JPS5951340B2 - Method for producing particulate inorganic ion exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a particulate inorganic ion exchanger suitable for high-temperature effluent treatment and chemical separation and purification of strongly radioactive substances.

In recent years, from the perspective of environmental purification or the effective use of resources, especially the light use of underground resources and marine resources, the treatment of water containing harmful substances such as arsenic and chromium, or the treatment of water containing valuable substances such as uranium, has become increasingly important. Technologies are being developed to efficiently concentrate and recover substances.

Since the above substances normally exist in water as ions such as arsenate ions, arsenite ions, chromate ions, uranyl carbonate, and uranyl sulfate, they can be treated, concentrated, and recovered using ion exchange resins. Conceivable.

However, ion exchange resins do not have sufficient selectivity for these ions, and in systems where large amounts of monovalent anions such as chloride ions and bromine ions coexist, the exchange capacity of the ions is significantly reduced.

Furthermore, ion exchange resins also have drawbacks such as lack of stability under high temperatures and strong radiation.

On the other hand, inorganic ion exchangers have superior stability at high temperatures and under strong radiation compared to ion exchange resins, and many also have selective exchange adsorption ability for special ions, so they can be used for water treatment at high temperatures and under strong radiation. separation and concentration of substances;
It can be expected to be applied to purification, etc.

In general, when inorganic ion exchangers are used in a packed column system, it is necessary to mold them into an appropriate size and shape in order to reduce liquid flow resistance. It is required to have sufficient underwater strength, acid resistance, and alkali resistance.

Possible methods for molding the inorganic ion exchanger include molding using silica sol, water glass, etc., which have been conventionally used as inorganic binders.

However, the molded product obtained using such a binder does not have sufficient alkali resistance, and its ion exchange ability is significantly lower than that before molding.

Furthermore, as a method for molding inorganic ion exchangers, methods using organic binders such as cellulose and synthetic/polymer materials can also be considered, but when organic binders are used, the heat resistance and acid resistance of the molded product However, it is insufficient in alkali resistance, and fusion and collapse between molded bodies occur when treated at high temperatures or when recycled with strong acids or strong alkalis.

In view of the above circumstances, the inventors of the present invention have conducted intensive studies to develop a method for producing a particulate inorganic ion exchanger that has a large ion exchange capacity and excellent heat resistance, underwater strength, acid resistance, and alkali resistance. It is a completed invention.

The gist of the present invention is to mix 8 moles of a hydrated oxide of titanium having an anatase or amorphous crystal structure with an inorganic acid of 0.1 to 7.2 moles and water of 0 to 50 moles. However, there is a method for producing a particulate inorganic ion exchanger which comprises mixing, extrusion, granulation, and drying.

The hydrated oxide of titanium (hereinafter referred to as titanic acid) used in the present invention is TiO2.1]H20 (n-0,5~
20) and has an anatase or amorphous crystal structure.

This titanic acid is obtained by heating and hydrolyzing an aqueous solution of titanium sulfate or titanium tetrachloride, or by adding a base to the aqueous solution to neutralize it, washing the solid content with water, filtering it, and then drying it. can get.

In addition, this titanic acid is titanium tetrabutoxide, tel~
It can also be obtained by hydrolyzing an alkoxyto such as line proxide in water, washing the solid content with water, and then drying it separately.

Inorganic acids used in the present invention include sulfuric acid, hydrochloric acid, phosphoric acid, and the like.

The amount of inorganic acid added is 0.1 to 7 moles per 8 moles of titanic acid.
．． 2 moles, but preferably 0.3 to 3.0 moles for sulfuric acid (as H2S04), 1.2 to 2.4 moles for hydrochloric acid (as HCl), and 1.2 moles for phosphoric acid (as H3PO4). ~3.6 moles.

In either case, when the amount of inorganic acid is less than 0.1 mol, the strength of the obtained particulate inorganic ion exchanger in water is significantly reduced.

Moreover, if the amount exceeds 7.2 mol, the viscosity of the mixed material increases markedly, and a phenomenon of solid-liquid separation occurs, making extrusion granulation difficult. Even after firing, excessive acid leaches out to the surface and further absorbs moisture, causing problems such as the particle surface becoming sticky.

The amount of water added is 0 to 50 moles per 8 moles of titanic acid, but the more preferable amount depends on the type of extrusion granulator, the pore size of the die and mesh, the extrusion speed, and the amount of inorganic acid added. It's a little rough.

For example, when the amount of inorganic acid added is 2 moles or less per 8 moles of titanic acid, it is more preferable to add 20 to 50 moles of water.

Mixing and cross-mixing should be thoroughly carried out using a batch type or continuous type kneading machine.

Mixed materials are granulated using a type of granulator that puts the granulated material under pressure during granulation, such as a screw type extrusion granulator, roll type extrusion granulator, or blade type extrusion granulator. Make it into granules.

By extrusion granulation, it is possible to produce an ion exchanger that is much stronger than that obtained by simply drying and calcining the kneaded material.

The particle size of the granules is generally 0.3 mmφ by appropriately selecting the hole diameter of the die or screen of the granulator.
It can be granulated into granules of the following types.

Next, the ion exchanger of the present invention is obtained by air-drying or heat-drying the granules.

When heating and drying is performed, the heating temperature is preferably 500°C or lower.

When the heating temperature exceeds 500°C, the ion exchange capacity of the resulting ion exchanger decreases significantly.

When the inorganic ion exchanger of the present invention is packed in a packed tower and used in a packed tower system in which water is passed through it, it is used as it is in granular form, or after being crushed and sized or spheroidized.

The particulate inorganic ion exchanger obtained by the present invention has excellent heat resistance, acid resistance, and alkali resistance, has high strength in water, has a large exchange capacity, and has a sufficiently high ion exchange rate.

Furthermore, in the present invention, the ion exchange ability of the particulate inorganic ion exchanger obtained can be greatly changed depending on the type of inorganic acid used.

That is, ion exchangers manufactured using sulfuric acid and hydrochloric acid are particularly excellent in selective exchange and adsorption ability for polyvalent anions.

Examples of these polyvalent anions include arsenate ion, arsenite ion, chromate ion, phosphate ion, uranyl carbonate, uranyl sulfate, molybdate ion, tungstate ion, vanadate ion, etc. It is effective in removing, concentrating, and recovering polyvalent anions in systems where chlorine ions, bromine ions, etc. coexist.

In addition, the ion exchanger of the present invention produced using phosphoric acid has an excellent ability to selectively exchange cations such as cesium, rubidium, silver, potassium, and barium, and is capable of removing these cations.
It is effective for concentration and recovery, and its selectivity can be used to separate alkali metals and alkaline earth metals.

The inorganic ion exchanger obtained by the present invention has excellent strength in water and stability over a wide range of pH, 1 and can be regenerated and backwashed in the same way as ordinary ion-exchanged citrus.

As the regenerating agent, hydrochloric acid, sulfuric acid, sodium hydroxide, potassium hydroxide, sodium carbonate, aqueous ammonia, etc. are used.

A method for treating harmful substances or concentrating and recovering valuable substances using the inorganic ion exchanger obtained in the present invention includes suspending the inorganic ion exchanger in water containing harmful or valuable substances. A so-called slurry one-type method is used, which involves water filtering.

It is also possible to use a packed tower system in which water containing harmful or valuable substances is passed through a packed tower filled with an inorganic ion exchanger.

Utilizing the above characteristics, the inorganic ion exchanger of the present invention can be used for separating and removing arsenic contained in ground water, geothermal water, ore processing wastewater, and recovering chromium from plating waste liquid.

The present invention will be explained below with reference to Examples.

Example 1 Anatase titanic acid (TiO(OH) 2 ), sulfuric acid, hydrochloric acid, phosphoric acid as an inorganic acid, and water were mixed in the proportions shown in Table 1, thoroughly kneaded with a kneader, and then extruded into a screw type. By passing through a screen with a diameter of 0.5 mm in a granulator, molded products with a length of 3 to 7 mm and a particle size of 0.5 mm were obtained.

Next, this molded product was dried in hot air at 110°C for 16 hours, and then fired in a steam furnace at 300°C for 3 hours to obtain a particulate inorganic ion exchanger.

300cc to judge the strength of the obtained ion exchanger.
Pour 300 cc of 90°C hot water into a beaker, add 10.0 g of the above ion exchanger to it, sift the powder thoroughly, and mash.
Fan rotation 150r, p, m with jar tester.

Stir for 5 hours.

Thereafter, the ion exchanger was filtered out, calcined in an electric furnace at 300° C. for 3 hours, and sieved through a 48-mesh sieve, and the proportion of powder passing through the 48-mesh sieve is shown in Table 1 as the particle fraction.

In addition, in order to evaluate the acid resistance and alkaline resistance of the same ion exchanger, 5% each of 25% thorium hydroxide aqueous solution and concentrated sulfuric acid was used.
Table 1 shows the results of observing changes in morphology after immersing 1.0 g of ion exchanger in 0 cc and leaving it for 24 hours with occasional shaking.

For comparison, silica gel (80% moisture content) was added to the titanic acid mentioned above.
and sulfur to lithium silicate aqueous solution (moisture content 68%) as the first
In addition to the results shown in the table, Table 1 also shows the results of similar evaluations of molded products obtained by molding in the same manner as above.

Example 2 Using amorphous titanic acid, sulfuric acid, and water in the proportions shown in Table 2, extrusion molding to a particle size of 1 mmφ was carried out in the same manner as in Example 1, drying, and firing, and the obtained molded product was used to conduct an example. Table 2 shows the strength in hot water (particle fraction) determined under the same conditions as in Example 1.

Separately, put 1100pp arsenic acid aqueous solution 1 as arsenic in a sample bottle.
Take 00ml and add the above molded product 1. Og was added and treated at 40° C. for 3 hours with stirring.

The residual amounts of arsenic obtained as a result are shown in Table 2.

Comparative Example 1 The arsenic adsorption ability of the amorphous titanic acid powder used in Example 2 was measured under the same conditions as in Example 2.

As a result, the arsenic residual degree was 40p, and the arsenic adsorption ability was considerably inferior to that of the granular inorganic ion exchanger obtained by the present invention.

Example 3 In the same manner as in Example 1, anatase titanic acid 800
Table 3 shows the results of evaluating the strength in water and the arsenic treatment in the same manner as in Example 2 for molded products made by adding 67 cc of concentrated sulfuric acid and 400 cc of water to the molded product, and changing the drying and firing conditions. Ta.

Claims (1)

[Claims] 1 0.1 to 7.2 inorganic acid per 8 moles of hydrated titanium oxide having anatase or amorphous crystal structure
1. A method for producing a particulate inorganic ion exchanger, which comprises mixing 0 to 50 moles of water, kneading, extruding, granulating, and drying.