JPH1053408A - Production of fluoromica - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing fluoromica from crystalline silica found abundantly as a natural resource by solid phase method. SOLUTION: This fluoromica is obtained by reaction of a mixture composed of 1mol of crystalline silica, 0.25-0.75mol of a metal fluoride selected from sodium fluoride, potassium fluoride and barium fluoride, 0.2-0.4mol of lithium fluoride and 0.4-0.6mol of a metal compound selected from magnesium compounds and transition metal compounds under heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing fluorine mica which is a layered silicate.

[0002]

2. Description of the Related Art As a method for synthesizing mica, a melting method and a solid phase method are known. The melting method requires a high temperature of 1400 ° C., but has an advantage that a large single crystal can be produced. Although it is difficult to produce large crystals by the solid phase method, it can be used for applications utilizing the colloid-forming ability and intercalation ability of mica, and has an advantage that the production temperature is good at 700 to 800 ° C. The present inventors have previously proposed a method for producing mica using amorphous silica as a raw material as a method for producing mica by the solid phase method (Japanese Patent Laid-Open No. 3-115113). This method
Promising as an industrial method because fluorine mica can be produced relatively easily, but its raw material is limited to amorphous silica, and the use of crystalline silica such as silica sand as a raw material is excluded. . The reason is that silica used as a reaction raw material in the solid-phase method is a common wisdom that amorphous silica is used up to now, and even if crystalline silica is used, the reaction does not proceed smoothly, and high-quality fluorine mica is obtained. This is because it was determined that they could not do so. However, the present inventors have surprisingly found that in the synthesis of the above-mentioned fluoromica by the solid-phase method, it is more preferable to use crystalline silica as a reaction raw material, but from the viewpoint of synthesis of high-quality mica, Was found to be an excellent method.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing fluorine mica from crystalline silica by a solid phase method.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, (a) 1 mol of crystalline silica, and (b) 0.25 to 0.75 mol of a metal fluoride selected from sodium fluoride, potassium fluoride and barium fluoride, (C) Lithium fluoride
2 to 0.4 mol, and (d) 0.4 to 0.6 of a metal compound selected from a magnesium compound and a transition metal compound.
The present invention provides a method for producing fluoromica, which comprises reacting a mixture of moles with heat.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted research on a method for producing fluorine mica by a solid-phase method. As a result, it has been found that surprisingly, high quality fluorine mica can be easily produced from crystalline silica. That is, SiO ₂ : NaF: LiF: M
When a mixed powder of gO = 1.0: 0.5: 0.25: 0.5 (molar ratio) was heated to 750 ° C. in a platinum crucible and the crucible content composition was examined over time during heating. When silica sand was used as silica, fluorine mica was formed one minute after heating, and NaMgF ₃ and a Na—Mg—Si—O-based compound (this compound was called a Y phase) were also formed. Also, MgO and LiF in the crucible disappeared 3 minutes after the start of heating, Y phase disappeared 6 minutes after the start of heating, and NaMgF ₃ disappeared 10 minutes after the start of the heating. On the other hand, when amorphous silica obtained by acid treatment of serpentine was used as silica, N
aMgF ₃ and Y phase were formed, and cristobalite crystals were formed in 3 minutes. Then, 10 minutes after the start of heating, the cristobalite crystals decreased, 60 minutes after the start of heating, the cristobalite crystals disappeared, and the total amount of silica changed to fluorine mica. This result indicates that the fluoromica is crystalline silica and Y
It shows that it is formed by a solid phase reaction between the phase and an intermediate product such as NaMgF ₃ , implying that amorphous silica is converted to crystalline silica and then to fluoromica. The present invention has been made based on the results of these studies.

The crystalline silica used as the component (a) in the present invention may be a natural product or a synthetic product, and specifically, natural products such as silica sand, silica stone, scale silica, cristobalite, and synthetic products such as synthetic cristobalite. Is used. The metal fluoride used as the component (b) in the present invention is at least one selected from sodium fluoride, potassium fluoride and barium fluoride, and the amount of the metal fluoride added is per mole of silica used as the component (a). 0.25 to 0.75 mol, preferably 0.
37-0.6 mol. In the present invention, lithium fluoride used as the component (c) is used in an amount of 0.2 to 0.4 mol, preferably 0.23 to 0.4 mol per mol of the silica used as the component (a).
3 moles. The metal compound used as the component (d) in the present invention is Mg, Al, Cu, Ni, ZnMn, Ti, F
e, oxides, hydroxides and carbonates of metals such as e and Co. Component (d) is added in an amount of 0.4 to 0.6 mol, preferably 0.45 mol per mol of silica used as component (a).
０．５0.55 mol. The above components (a) to (d) may be pulverized to a particle size of 100 mesh or less, preferably 250 mesh or less, and then sufficiently mixed and reacted by heating.

The reaction temperature differs depending on the type of silica used and the raw material composition. When the component (a) is silica sand and the Mg compound is used alone as the component (d) [hereinafter, the Mg compound is used alone as the component (d)] The mica obtained after this is called Mg mica] is 6
The temperature is from 00 to 800 ° C, preferably from 700 to 770 ° C.
In order to obtain a single phase of Mg mica in which only water-soluble fluorides such as NaF and LiF are recognized in addition to Mg mica by X-ray diffraction, it takes a longer time as the reaction temperature becomes lower. For example, using silica sand as the component (a), SiO ₂ : NaF: LiF: M
When reacting a mixed powder of gO = 1.0: 0.5: 0.25: 0.5 (molar ratio), the reaction temperature becomes a single phase at 750 ° C. for 1 hour but becomes a single phase at 725 ° C. Takes 3 hours to obtain When the component (a) is synthetic cristobalite, the powder having the above composition is reacted at 750 ° C.
A single phase is obtained in 0 minutes. When the reaction temperature is lower than 600 ° C., the mica formation reaction does not proceed, and when the reaction temperature exceeds 800 ° C., SiF ₄ is decomposed and desorbed from the generated fluorine mica. This causes problems such as binding of the reaction mixture.

[0008] The fluoromica produced by the above method is recovered as it is or after being crushed and washed with water to dissolve and remove unreacted metal fluoride, and then dispersed in water or dried. The time required for dissolving and removing the unreacted metal fluoride is about 5 minutes at room temperature. M obtained as described above
g mica is a 1Md-type lamellar microcrystalline mica having a teniolite composition, and is a limited swelling mica that adsorbs a monolayer of water between layers. Further, substitutional mica in which a part of Mg is substituted by Cu or Ni is non-swelling, but other substitutional mica is limited swelling mica similar to Mg mica. The substitution mica has the same crystal form and the like as Mg mica. The fluoromica produced by the method of the present invention can be used as a catalyst carrier, a filler, an adsorbent, a deodorant and the like. Further, since substitution mica is often colored, it can be used as a coloring agent for paints and the like in addition to the above.

[0009]

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

EXAMPLE 1 Silica sand special powder D [SiO ₂ purity 96.
9%, a water content of 1.0% and a particle size of 300 mesh or less] are used as raw material silica, and predetermined amounts of MgO, NaF and LiF for a reagent manufactured by Wako Pure Chemical Industries, Ltd. are added thereto, and the mixture is agate. The mixture was ground and mixed in a mortar to obtain a mixed powder having a particle size of 280 mesh or less. SiO ₂ : NaF: LiF: M
gO = 1.0: 0.5: 0.25: 0.5. Charge 2 g of the mixed powder into a platinum crucible having an internal volume of 30 ml,
This was heated to 750 ° C. for 1 hour in an electric furnace. From the results of X-ray diffraction of the reaction product, no unreacted material other than NaF was found in the product, and almost all of the silica sand used was changed to Mg mica. When the product was observed with a transmission electron microscope, the mica formed was thin hexagonal plate-like crystallites, and the unit sheets were regularly stacked at intervals of about 1 nm. Then, from the X-ray diffraction diagram, the mica was 1Md in which unit cells were randomly stacked.
It turned out to be a type. After the reaction product was washed with water and centrifuged to remove NaF, and analyzed by X-ray diffraction, the NaF was completely removed. In the product after the washing treatment, one molecular layer of water was adsorbed between layers. The swelling mica had the same shape as before swelling.

Example 2 The same experiment as in Example 1 was conducted except that the reaction temperature and the reaction time were changed. That is, the same mixed powder as that used in Example 1 was used and calcined at 725 ° C. for 3 hours. As a result, all of the obtained reaction products were Mg mica similar to the reaction product of Example 1.

Example 3 The raw material silica was changed to synthetic cristobalite (powder having a SiO ₂ purity of 99.5%, a water content of 1% and a particle size of 300 mesh or less) sold by Iwamoto Mineral Products Co., Ltd. Production of Mg mica was attempted in the same manner as in Example 1. As a result, Mg mica similar to the product of Example 1 was obtained only by heating at 750 ° C. for 50 minutes.

[0013]

According to the method of the present invention, powdery mica can be produced at a low temperature from crystalline silica with abundant resources. Powdered mica is a powder having a wide variety of functions such as colloid-forming ability, intercalation ability, film-forming ability, ion-exchange ability, and complexing ability with organic and inorganic substances. It is a powder that can be used as an agent, a deodorant, a raw material for producing ceramics and sensors, and a coloring agent for paints.

Claims (1)

[Claims] 1. (a) 1 mol of crystalline silica, (b) 0.25 to 0.75 mol of a metal fluoride selected from sodium fluoride, potassium fluoride and barium fluoride, and (c) 0.2 to 0.4 mol of lithium fluoride;
(D) A method for producing fluoromica, comprising heating and reacting a mixture of 0.4 to 0.6 mol of a metal compound selected from a magnesium compound and a transition metal compound.