JP2007051022A - Hydrotalcite-like compound, its manufacture method, and anion remover - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrotalcite-like compound obtained from dust generated from an electric furnace for producing calcium carbide as a raw material, its manufacture method, and an anion remover. <P>SOLUTION: This hydrotalcite-like compound is manufactured by using dust, generated from an electric furnace for producing calcium carbide, as a raw material. This method for manufacturing a hydrotalcite-like compound comprises an extraction step of acid treating the dust generated from the electric furnace for producing calcium carbide to extract an acid-soluble metal component and a precipitation step of adding aluminum ions to a solution containing the acid-soluble metal component and adjusting pH to precipitate the generated product. This anion remover contains the hydrotalcite-like compound. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrotalcite-like compound using dust generated from an electric furnace for producing calcium carbide as a raw material, a production method thereof, and an anion removing agent.

Dust generated from an electric furnace for producing calcium carbide is disposed as landfill as industrial waste, or used as a part of a cement raw material or a raw material for a desulfurization accelerator (Patent Documents 1 and 2). Moreover, the method of manufacturing a hydrotalcite-like compound from the melted dust discharged | emitted from the cast iron blast furnace is disclosed (patent document 3).
Japanese Patent Publication No. 60-5643 Japanese Patent Publication No. 1-41682 JP 2004-167408 A

  An object of the present invention is to provide a hydrotalcite-like compound produced using dust generated from an electric furnace for producing calcium carbide as a raw material, a production method thereof, and an anion remover.

  That is, the present invention includes (1) a hydrotalcite-like compound produced using dust generated from an electric furnace for producing calcium carbide as a raw material, and (2) an acid-soluble metal obtained by acid treatment of dust produced from an electric furnace for producing calcium carbide. A method for producing a hydrotalcite-like compound comprising: an extraction step of extracting components; and a precipitation step of adding aluminum ions to a solution containing an acid-soluble metal component and adjusting the pH to precipitate the product. (3) Hydrotalcite-like compound produced by the production method of (2), (4) An anion remover containing the hydrotalcite-like compound of (1) or (3).

  According to the present invention, a hydrotalcite-like compound can be produced using dust generated from an electric furnace for producing calcium carbide as a raw material. The hydrotalcite-like compound is an excellent anion removing agent.

Hydrotalcite-like compounds of the present invention, the composition formula is represented by ^{_{[M 2+ 1-x M 3+}} x (OH) 2] [A n- x / n · nH 2 O], also called layered double hydroxides A compound. Here ^{M 2+} and ^{M 3+} are divalent and trivalent metals ^{respectively, A n-represents} an n-valent anion. The hydrotalcite-like compound has a structure in which a host layer composed of a hydroxide layer and a guest layer composed of an anion and interlayer water are alternately stacked. Usually, the positive charge amount of the host layer changes depending on the substitution ratio (n) of divalent and trivalent metal ions in the host layer, and the anion in the guest layer compensates for this. The anion of the guest layer is known as an inorganic ion exchanger because it can be exchanged with other anions in a solution in which a hydrotalcite-like compound is immersed.

Moreover, the hydrotalcite-like compound can change the anion exchange property by changing the metal ion species constituting the host layer and the anion species constituting the guest layer at the time of synthesis. Examples of the divalent metal constituting the guest layer include magnesium, zinc, cobalt, nickel, copper, manganese, calcium, and the like. Among these, magnesium is preferable. Examples of the trivalent metal include aluminum, iron, chromium, and the like. Among these, aluminum is preferable. The target anions include phosphoric acid, halogen, nitric acid, nitrous acid, carbonic acid, sulfuric acid, arsenic acid, arsenous acid, chromic acid, hydroxide ions, and the like.
Accordingly, the hydrotalcite-like compound can be used as an anion removing agent.

The present invention is dust generated from an electric furnace for producing calcium carbide (hereinafter referred to as the present dust), for example, dust generated from an auxiliary equipment such as an electric furnace for producing calcium carbide and a raw material supply line attached thereto. This dust is obtained, for example, by shutting off exhaust gas discharged from the calcium carbide manufacturing electric furnace from outside air, guiding it through a flue to a back filter, a sedimentation tank or the like, and collecting it when dust is removed or separated.
The main components of the dust are carbon, calcium compound, magnesium compound, manganese compound and the like. The average particle size of the dust used in the present invention is preferably in the range of 0.01 to 0.5 μm.

A method for producing a hydrotalcite-like compound using the dust as a raw material is as follows, for example.
It consists of an extraction process to extract the acid-soluble metal component by acid treatment of this dust, and a precipitation process to add aluminum ions to the solution containing the acid-soluble metal component and adjust the pH to precipitate the product. is there.

  In the extraction step, the dust is treated with an acid to extract acid-soluble metal components such as calcium, magnesium and manganese, and a solution containing the acid-soluble metal component is obtained. Examples of the acid include inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as citric acid, malic acid, and acetic acid.

  In the precipitation step, a hydrotalcite-like compound can be precipitated and produced by adding aluminum ions to a solution containing an acid-soluble metal component and adjusting the pH to preferably 8 or more, more preferably 9 or more. Examples of the aluminum ion supply solution that uses aluminum ions for addition include aqueous solutions of aluminum chloride, polyaluminum chloride, aluminum sulfate, aluminum nitrate, and sodium aluminate. Among these, an aqueous solution of an aluminum salt containing the same anion as the acid used when extracting the metal component from the present dust is more desirable. Examples of the pH adjusting solution used for adjusting the pH include alkalis such as sodium hydroxide, sodium carbonate, calcium hydroxide, and magnesium hydroxide.

  The hydrotalcite-like compound produced in the precipitation step is filtered off using a filter paper or filter and dried, for example, as an additive for resins such as an anion remover, antacid, or flame retardant Can be used. The hydrotalcite-like compound is dried at a temperature as high as 500 ° C. or more to form an oxide, which can be used as an anion adsorbent for wastewater treatment and the like.

"Example 1"
This dust (average particle size 0.35μm: measured with a laser particle size distribution measuring instrument) is obtained by blocking the exhaust gas discharged from the calcium carbide manufacturing furnace from the outside air, guiding it to the back filter through the flue, and removing the dust. Got. This dust was dried with a dryer at 105 ° C. for 24 hours, and the components were measured with a scanning X-ray fluorescence analyzer (XRF: ZSX100e manufactured by Rigaku Corporation). As a result, 24.8% by mass of calcium oxide and 10.7% by mass of magnesium oxide were obtained. %, Manganese oxide 0.8% by mass, and other 63.7% by mass.

  50 g of this dust was dissolved in 500 mL of 1 mol / L hydrochloric acid, the insoluble matter was removed using a membrane filter having a pore size of 0.2 μm, and an acid-soluble metal component was extracted to obtain an extract.

  When 21.5 mL of 0.1 mol / L aluminum chloride solution was added to 50 mL of the extract, a white precipitate was formed. When adding the aluminum chloride solution, a 0.1 mol / L sodium hydroxide solution is also used, the reaction temperature is adjusted to 58 to 62 ° C., and the pH of the reaction solution is adjusted to 9.5 to 10.5. It was adjusted.

  The precipitate was allowed to stand at room temperature for 1 hour and aged, then filtered through filter paper, washed with water, and dried to obtain a product. When the crystal structure of this product was analyzed with an X-ray diffractometer (XRD: Rigaku MultiFlex, measurement conditions: Cu Kα, 40 kV, 40 mA), it was confirmed to be a hydrotalcite-like compound as shown in FIG. It was done. The circles in the figure indicate hydrotalcite peaks. Furthermore, when the composition analysis was conducted by XRF, the results shown in Table 1 were obtained, and the hydrotalcite-like compound had a host layer composed of Mg and Mn as the divalent metal and Al as the trivalent metal. Was confirmed. In addition, it was considered that the guest layer contained chlorine ions, and also contained hydroxide ions.

Furthermore, commercially available sodium dihydrogen phosphate was dissolved in pure water to prepare a solution having a phosphoric acid (PO ₄ ²⁻ ) ion concentration of 32 ppm, and 50 mg of the synthetic hydrotalcite-like compound was added to 50 mL of this sample solution, The mixture was stirred at 20 ° C. for 2 hours. After stirring, the mixture was filtered through a membrane filter having a pore size of 0.2 μm, and the phosphate ion concentration in the filtrate was measured with an ion chromatograph (personal ion analyzer PIA-1000 manufactured by Shimadzu Corporation) to examine phosphate ion adsorptivity. . As a result, as shown in Table 2, the synthetic hydrotalcite-like compound showed a decrease in phosphate ion concentration, confirming the effect as an anion remover.

"Example 2"
A precipitate was obtained in the same manner as in Example 1 except that 32.0 mL of a 0.1 mol / L aluminum chloride solution was added to 50 mL of the extract of Example 1. When the precipitate was confirmed by XRD and XRF, it was confirmed to be a hydrotalcite-like compound as in Example 1. Moreover, when the phosphate ion removal effect was investigated using the phosphoric acid solution similarly to Example 1, as shown in Table 2, phosphate ion is below the detection lower limit of an ion chromatograph, and this hydrotalcite The phosphate ion removal effect of the like compound was confirmed.

“Comparative Example 1”
Using a commercially available magnesium chloride and aluminum chloride as a reagent, a solution in which the molar ratio of magnesium to aluminum was 1: 3 was prepared, and the same operation as in Example 1 was performed. Obtained. Moreover, when the phosphate ion removal effect was investigated using the phosphoric acid solution similarly to Example 1, as shown in Table 2, although the phosphate ion removal effect was recognized, it remains compared with Example 1 The ion concentration was high.

"Comparative Example 2"
Except that the hydrotalcite-like compound was not used, the same operation as in Example 1 was performed to examine the phosphate ion removal effect. The results are shown in Table 2.

  ADVANTAGE OF THE INVENTION According to this invention, a hydrotalcite-like compound can be manufactured from the dust collection dust of the electric furnace for carbide manufacture as a raw material. This hydrotalcite-like compound can be used as an excellent anion remover having a function of removing anions such as phosphate ions.

It is an X-ray diffraction pattern of the compounds obtained in Example 1 (a) and Example 2 (b).

Claims (4)

Hydrotalcite-like compound produced from dust generated from an electric furnace for calcium carbide production. Extraction process to extract acid-soluble metal component by acid treatment of dust generated from electric furnace for calcium carbide production, and aluminum ion added to solution containing acid-soluble metal component, pH adjusted to 8 or more The manufacturing method of the hydrotalcite-like compound characterized by including the precipitation process which precipitates a thing. A hydrotalcite-like compound produced by the production method according to claim 2. An anion remover containing the hydrotalcite-like compound according to claim 1 or 3.

Images