JP2007275733A - Recycling method of used titanium compound as fluorine collector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop a method of recovering used titanium compounds from waste containing titanium compounds and using for a fluorine treatment. <P>SOLUTION: The recycling method of the titanium compounds as the collector comprises the following processes: the waste containing the titanium compounds is subjected to pretreatments of an alkali treatment, an acid treatment, and a chelating agent addition treatment and/or a flocculant addition treatment, and the obtained titanium-containing compound is used to collect fluorine, and fluorine-containing compounds from drain containing fluorine, and the fluorine-containing compounds at a low concentration. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of treating a titanium compound in waste containing a titanium compound and recycling it as a scavenger for fluorine and fluorine-containing compounds.

For wastewater treatment of wastewater containing fluorine and its compounds, such as industrial wastewater, a one-stage coagulation treatment method using calcium salt is widely used. In general, a method of recovering fluorine as calcium fluoride by using calcium carbonate or calcium chloride is used for treating ultra-high concentration (several thousand ppm or more) of fluorine. However, such a one-stage treatment method can usually treat only up to about 10 to 20 mg / L (ppm) as fluorine. Therefore, in order to stably treat fluorine to a concentration of 8 mg / L or less of the wastewater standard value,
1) A method in which an aluminum salt such as polyaluminum chloride (PAC) or a sulfuric acid band is added to adsorb and coprecipitate fluorine in aluminum hydroxide, and the coagulation treatment facility is treated in two stages
2) A method of adding an additional fluorine processing aid such as rare earth to the aluminum salt
3) Additional methods such as phosphomethylamino chelate resin that adsorbs aluminum ions, resin supported on a metal surface such as zirconium, and adsorbent that supports hydrous cerium on a polymer compound. It is necessary to take (see Non-Patent Document 1).

  However, in the first two-stage treatment method, the amount of sludge generated is increased by the amount of aluminum salt injection, and the cost is increased. Moreover, it is considered that it is difficult to install new facilities because a large amount of cost and additional space are required for an establishment that is currently performing one-stage processing to move to two-stage equipment. The method of adding the second fluorine processing aid does not require a new capital investment, so the initial cost is low, but there is a problem that the running cost is more expensive than the one-step processing method. It has been pointed out that the third resin treatment is expensive and inappropriate when the amount of drainage is large. In addition to the above-mentioned problems, the environmental standard value is 0.8 ppm, which is lower than the emission standard value. Therefore, development of further new processing technology is required to clear this environmental standard value. .

2003 Water Pollution Unregulated Substances Release Status Survey (Toray Research Center, Inc., March 2004)

  Accordingly, an object of the present invention is to provide a method for recovering used titanium compounds from wastes containing titanium compounds and using them as fluorine scavengers for fluorine and fluorine-containing compounds contained in the effluent. It is in.

  According to the present invention, the waste containing the titanium compound is subjected to pretreatment of alkali treatment, acid treatment, chelating agent addition treatment and / or flocculant addition treatment, and then the obtained titanium-containing compound is reduced to a low concentration. There is provided a recycling method as a scavenger for a titanium compound, which is used for collecting fluorine and a fluorine-containing compound from an effluent containing fluorine and a fluorine-containing compound.

  According to the present invention, by recovering a titanium compound from waste containing a used titanium compound and using it as a scavenger for fluorine and fluorine-containing compounds in the effluent, the drainage standard value for fluoride ions is 8 ppm. Of course, processing can be performed up to an environmental standard value of 0.8 ppm or less.

As a result of researches to solve the above-mentioned problems, the inventors of the present invention have found that in order to remove low-concentration fluoride ions in the effluent, in the form of fluorine compounds with low solubility in order to prevent re-elution of fluorine. We thought it was effective to collect. In addition, the ion exchange reaction between hydroxide ions and fluoride ions in metal hydroxides is suitable as a treatment method for fluoride ions because the charge of the entire compound does not change. In the concept of Soft Acids and Bases, it belongs to a hard base (for example, OH ⁻ , F ⁻ , Cl ⁻ ) and has an affinity for hard acids (Ti ⁴⁺ , Al ³⁺ , Fe ³⁺ , Mg ²⁺ , Ca ²⁺ ) Therefore, the treatment method using a metal compound having a large oxidation number such as aluminum or iron which is a hard acid was considered effective. Therefore, paying attention to the titanium compound in the waste, we examined the removal of fluoride ions in the effluent using this titanium compound having a large oxidation number. Discovered that fluoride ions can be treated to a concentration below the reference value by using a pre-treatment method for the used titanium compound in waste as a scavenger for fluorine and fluorine-containing compounds in the effluent. It was. According to the present invention, the spent titanium compound in the waste or the like is used, so that low-concentration fluoride ions can be easily removed at low cost.

  Electroplating industry, semiconductor manufacturing industry, electron tube manufacturing industry, glass industry, etc. can be cited as industries that produce fluorine and fluorine-containing compounds that exceed the wastewater standard value. In order to comply with environmental standards, it is necessary to newly install facilities, and this is expected to be a significant burden due to the introduction cost and subsequent processing cost increase. On the other hand, since the method of the present invention can be processed using an existing coagulation sedimentation apparatus, the initial investment cost is low, and the burden on the operator at the time of introduction can be minimized. In addition, according to the present invention, since it is possible to treat not only the drainage standard value of fluoride ions of 8 ppm but also the environmental standard value of 0.8 ppm or less, it is possible to cope with the case where new regulations are implemented. .

  The titanium compound used as a collecting agent in the present invention is discharged as solid waste from industries such as the plastic industry, the electronics industry, the metal industry, the pharmaceutical industry, and the pigment industry, and is partially used for every recovery. . The present inventors pay attention to the waste containing such a titanium compound, and if necessary, the waste is only subjected to treatment such as washing, dissolution, impurity removal, separation and recovery, alkali treatment, acid treatment, chelating agent. Addition treatment and / or flocculant addition treatment is performed to recover the titanium-containing compound. These treatment methods are all known in the field of titanium chemistry, and are not particularly specific in the present invention, but typical methods will be described below (however, the treatment method of the present invention is not limited to these methods). Needless to say, it is not limited to.) Moreover, these processing methods can be used in combination as necessary.

An alkali such as sodium hydroxide or sodium carbonate is added to a titanium compound dissolved with an alkali-treated acid or a titanium compound obtained as a slurry to adjust the pH to 10 or more to produce a titanium hydroxide.

The pH is adjusted by adding an acid to the solution and slurry containing the titanium compound whose pH is increased by the acid treatment alkali treatment (pH 4 or less). An acid may be added to dissolve impurities.

When washing the titanium hydroxide formed after alkali treatment of chelating agent addition process titanium compounds, there is also a case of adding a chelating agent to take a crosslinking structure in order to increase the particle size because the sedimentation velocity becomes slow.

The form of the titanium hydroxide compound treated with the flocculant is unstable, but it has been found that the use of various polyvalent organic acids is effective for pH adjustment and agglomeration effect. However, excessive addition reduces the ability to collect fluoride ions.

  According to the present invention, wastewater containing fluorine and a fluorine compound at a low concentration (for example, 3 ppm or less as fluorine ions) is treated using the titanium compound (for example, titanium hydroxide, titanium oxide) recovered by the above treatment method. The processing equipment flow is not particularly limited, and for example, processing can be performed according to the flow shown in FIG. That is, waste water 1 containing fluorine and a fluorine compound is put into a waste water storage tank 2 and then supplied to a waste water treatment tank 3 by a pump or the like. The wastewater treatment tank 3 is supplied with a titanium compound scavenger 4 separately treated by the above method in a liquid form, and a pH adjuster (for example, acid such as hydrochloric acid or sulfuric acid, acidic wastewater for alkaline wastewater). Can be supplied with sodium hydroxide solution, acetic acid buffer) and the like.

  There is no particular limitation on the conditions when the wastewater 1 containing fluorine and / or fluorine compound is treated with the titanium compound scavenger 4, but the pH of the liquid is preferably 1 to 4 (as the pH adjuster, hydrochloric acid And sulfuric acid and sodium hydroxide), the temperature is normal temperature, and the residence time is preferably 0.5 to 2 hours.

  The method of treating the waste water containing fluorine and / or fluorine compound with a titanium compound scavenger can be carried out in a continuous batch or semi-batch mode. Although there is no restriction | limiting in particular in the addition amount of a titanium compound scavenger, 10-15 mol as a titanium atom per 1 mol of fluorine ions in waste water from the viewpoint of suppressing cost after processing a low concentration fluoride ion can be performed. Is preferred.

  Using the titanium compound used according to the present invention as a scavenger, fluorine and fluorine compounds in the waste water are collected as a titanium fluoride compound, and this is recovered, for example, in a precipitation tank 5 conventionally used. The clear water can be discharged as the treated water 6 as it is, and the precipitate is recovered as sludge.

  Hereinafter, the present invention will be described in more detail based on examples, but it is needless to say that the present invention is not limited to the following examples.

Example 1
The amount of fluoride ions eluted from the incinerated ash was measured by adding 10 g of incinerated ash and 100 ml of pure water to a 100 ml polyethylene bottle. The fluoride ion collection experiment was conducted by adding 100 ml of a sodium fluoride solution having a fluoride ion concentration of 3 ppm and a pretreated collection agent to a 100 ml polyethylene bottle. Each was shaken for 6 hours, allowed to stand, filtered through a membrane filter (material: cellulose acetate) having a pore size of 0.2 μm, and then measured for fluoride ion concentration by ion chromatography (DX-100 manufactured by DIONEX). .

  First, the fluoride ion concentration eluted from the incineration ash was measured. Incineration ash prepared the incineration ash of company A (paper industry), and it was confirmed that the incineration ash of company A contained 1.43 ppm of fluoride ions. This is thought to be due to the fact that the incinerated material contains fluororesin and decomposed by combustion at high temperature, producing fluoride ions.

  As shown in Table I below, the titanium-containing waste obtained from the waste catalyst of Company B (pharmaceutical industry) was obtained by alkali treatment, neutralization treatment or chelating agent addition treatment as shown below. Fluorine removal treatment of the incinerated ash eluate A from Company A was carried out using the containing collection agents X, Y and Z. The results are shown in Table I.

Table I Preparation of footnote collecting agent X: Stirring with 0.1 mol / L sodium carbonate solution, followed by filtration and drying at 50 ° C. for 2.5 hours.
Preparation of collection agent Y: After stirring with 0.1 mol / L sodium carbonate solution, stirring with 0.1 mol / L hydrochloric acid, and after filtration, the mixture was dried at 50 ° C. for 2.5 hours.
Preparation of scavenger Z: Stirring with 0.1 mol / L sodium carbonate solution followed by stirring with 0.1 mol / L hydrochloric acid followed by stirring with 0.1 mol / L sodium oxalate solution After filtration, it was dried at 50 ° C. for 2.5 hours.

As described above, when an experiment for collecting fluoride ions in a low concentration region was performed using a titanium-containing collection agent obtained by performing alkali treatment, neutralization treatment, and chelating agent addition treatment, the collection agent X As for Y and Y, it became possible to treat to a concentration below the environmental standard value (0.8 ppm). On the other hand, since the collection agent Z had a high concentration of oxalate ions used as a flocculant, the collection rate decreased. About the drying conditions at the time of titanium-containing collection agent preparation, the collection rate decreased as the drying temperature of the titanium-containing collection agent increased. Therefore, addition without drying is desirable. About the pH conditions of the solution in the case of a process, when pH before shaking was 1-4 vicinity, it recognized that the collection rate was the highest.
Example 2
Example 1 was prepared by preparing 100 ml of two types of sodium fluoride (NAF) aqueous solution samples B and C having a fluoride ion concentration of 3 ppm and 20 ppm, and using the collection agent Y in amounts of 0.1 g, 0.5 g and 1 g. Similarly, fluorine ions in the NaF aqueous solution were removed.
The results are shown in Table II.

  According to the present invention, the titanium compound generated from various industrial processes and the titanium compound as waste are subjected to alkali treatment, acid treatment, chelating agent addition treatment and / or flocculant addition treatment, Using the obtained titanium-containing compound, fluorine and the fluorine-containing compound can be collected from the drainage liquid containing a low concentration of fluorine and the fluorine-containing compound to obtain a fluorine ion concentration that meets environmental standards.

It is drawing which shows an example of the flow of the recycling method of the titanium compound of this invention.

Explanation of symbols

1 Wastewater 2 Wastewater storage tank 3 Wastewater treatment tank 4 Titanium compound collector 5 Precipitation tank 6 Treated water

Claims (3)

  The waste containing the titanium compound is subjected to alkali treatment, acid treatment, chelating agent addition treatment and / or flocculant addition treatment, and the resulting titanium-containing compound is reduced to low concentrations of fluorine and fluorine-containing compounds. A recycling method as a scavenger for a titanium compound, characterized by being used for collecting fluorine and a fluorine-containing compound from a drainage liquid.   A titanium-containing compound obtained by pretreatment of the titanium compound by producing a titanium hydroxide by alkali treatment, separating from impurities by sedimentation and washing, and neutralizing treatment, chelating agent and / or flocculant addition. The method of Claim 1 which adjusts pH by adding an acid.   The collection of fluorine and a fluorine-containing compound in the drainage liquid is carried out by adding the titanium-containing compound obtained by the pretreatment of claim 2 to the wastewater and adjusting the pH to 4 or less with a pH adjuster. the method of.

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