JPH03208815A - Production of fluoride - Google Patents

Abstract

PURPOSE:To obtain the fluoride of an element having a low ionization tendency without any difficulty in filtering the product and any problem relating to the environment by allowing the chloride of an element having a low ionization tendency to react with the fluoride of an element having a higher ionization tendency than the former element in their molten state. CONSTITUTION:The chloride of an element having a low ionization tendency is allowed to react with the fluoride of an element having a higher ionization tendency than the former element in their molten state to obtain the fluoride of the element having a lower ionization tendency. In this method, when the chloride of an element having a lower ionization tendency and the chloride of an element having a higher ionization tendency are mixed, the melting rate is increased when the fluoride of the element having a higher ionization tendency is subjected to a reaction, and the reaction proceeds rapidly. Magnesium chloride is allowed to react with calcium fluoride by this method to obtain magnesium fluoride.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a process for producing a carbide, particularly magnesium carbide.

(Prior art) Aluminum fluoride (Aj!Fs), sodium fluoroaluminate (Nas^IF, ), sodium fluoride (Na
F), various fluorides such as magnesium fluoride (MgFt) are used industrially.

Among these agglomerates, magnesium agglomerate is used as a coating material for lenses or as a window material for laser infrared equipment, and various methods have been used or proposed to produce it. 0 Examples include (1) a method of reacting magnesium chloride with hydrofluoric acid, (2) a method of reacting ammonium fluoride with magnesium carbonate, and the like.

Among these methods, method (2) adds a hydrofluoric acid aqueous solution to a magnesium chloride aqueous solution, and the following reaction (1) MgCj! i+
2HF-4NgF□+2)ICj! ...This is a method for obtaining magnesium fluoride using (1), but the resulting magnesium fluoride becomes a fine colloid and is difficult to filter, resulting in poor productivity.Also, since hydrofluoric acid is handled, there are environmental issues such as equipment measures. Sufficient consideration must be given to these aspects.

In addition, in the method (2) of reacting ammonium fluoride and magnesium carbonate, the reaction progresses more slowly than the reaction (1) above.2NHJ + MgCO5→MgFz+(NHa)
This is a method for obtaining magnesium fluoride by the reaction of CO,...(2), but the raw materials, ie, ammonium fluoride and magnesium carbonate, are expensive, and there is a problem in terms of cost.

(Problems to be Solved by the Invention) The present invention provides an inexpensive method for producing magnesium carbide that is free from process problems such as the difficulty of filtering the product and environmental measures as described above. The purpose is to

(Means for Solving the Problems) The gist of the present invention is as follows: [In a molten state, a chloride of an element with a small ionization tendency is reacted with a fluoride of an element that has a larger ionization tendency than this element, A method for producing a fluoride characterized by obtaining a fluoride.

When metals are arranged in descending order of ionization tendency, in Li1,
Ba, Ca, Na, Mg5Affi, ZnSF
e, Ni, -. Elements with a large ionization tendency and elements with a small ionization tendency may be selected from these as necessary.

Therefore, for example, magnesium chloride is used as a chloride of an element with a small ionization tendency, and calcium fluoride is used as a fluoride of an element with a larger ionization tendency than this element (Mg). Magnesium carbide can be produced by reacting calcium.

By mixing the chloride of an element with a smaller ionization tendency with the chloride of an element with a larger ionization tendency, the melting rate will be faster when reacting with the fluoride of the element with a larger ionization tendency. The reaction proceeds quickly.

(Function) As a specific example of the method of the present invention, production of magnesium butoxide will be explained.

FIG. 1 is a schematic process (Step A) showing an example of the manufacturing process of magnesium butoxide based on the method of the present invention.

In the process shown in the figure, first, magnesium chloride is melted, and then calcium fluoride is poured into the molten magnesium chloride. Calcium fluoride melts,
It reacts with magnesium chloride as shown in equation (3) below to produce magnesium fluoride and calcium chloride.

MgCj! t+CaFi →MgF1+CaCj!
z...(3) Next, the mixed salt of magnesium fluoride and calcium chloride produced by the reaction of formula (3) above is cooled and solidified, and water is added to the obtained solid salt. Calcium chloride has a high solubility in water, so it dissolves, while magnesium chloride, which has a low solubility, does not dissolve and remains suspended in water. Magnesium fluoride can be obtained by filtering this suspension.

Magnesium oxide produced by reaction with oxygen in the air in the magnesium carbide thus obtained.

If rum (MgO) and calcium oxide (Cab) are mixed as impurities, these impurities are dissolved and removed with acid. The acid used may be hydrochloric acid, but acetic acid, which does not dissolve magnesium fluoride, is preferred.

Finally, the adhering acid is washed with water and dried to obtain magnesium carbide.

In the above manufacturing process, when melting magnesium chloride, if calcium chloride is mixed and melted to form a mixed molten salt as shown by the broken line, the melting rate when calcium fluoride is added to this molten salt will be The reaction between magnesium chloride and calcium fluoride proceeds more rapidly than when using only magnesium.

Moreover, since magnesium butoxide is produced by the reaction of formula (3), it is sufficient to react equimolar amounts of magnesium chloride and calcium fluoride, but if calcium butoxide remains unreacted, the above-mentioned "cooling Remaining in the mixed salt of magnesium butoxide and calcium chloride solidified in the `` process,
It does not dissolve in the next "dissolution" step with water and remains as an impurity in the fragmented magnesium. Therefore, in order to prevent calcium fluoride from remaining, the amount of magnesium chloride added should be greater than the theoretical amount calculated from equation (3), and the molar ratio of magnesium chloride to calcium fluoride should be 1.1 or more. . It is desirable to prevent calcium chloride from remaining unreacted in this way. Furthermore, even if unreacted magnesium chloride gets mixed into the cooled and solidified mixed salt, it will not dissolve in the water during the "dissolution" process. It dissolves and is easily removed.

In the above manufacturing process (Step A), calcium butoxide was added to molten magnesium chloride, but magnesium chloride and calcium butoxide may be melted at the same time, or calcium chloride may be further added and the champion may be melted at the same time. Good too.

In the above manufacturing process (Step A), the mixed salt produced by the reaction of formula (3) was cooled, and calcium chloride and magnesium chloride in this mixed salt were removed by extraction with water. However, the melting point of these chlorides (Ca(/! *Near 72"C1
MgCj! Taking advantage of the fact that the temperature (near 14°C) is lower than the melting point of magnesium chloride (1260°C), as shown in step B in Figure 2, the temperature between the melting points of both, that is, the chloride is in a molten state. It is possible to cool down to a temperature at which the magnesium salt present in the solid state is in a solid state, and then filter it, and the melt that has passed through the filter may be returned to the previous step and reused. Magnesium oxide and calcium oxide produced by oxidation in magnesium (melting point, Hg (h2800″C, Cab: 2572°C)
If it is mixed in as an impurity as described above, it must be dissolved and removed with acid after cooling.

The above explanation is for producing magnesium fluoride from magnesium chloride and calcium fluoride, but if chloride and fluoride are combined in consideration of their ionization tendency, for example, sodium fluoride can be produced by the reaction of formula (4) below. (Na
F) can be obtained.

2NaCj! +CaFx =2NaF+CaC1z
...(4) Furthermore, if lithium butoxide (LiF) is used, other fluorides such as barium butoxide (BaFi) can be used.
, potassium butoxide (KF), etc. can also be easily produced. However, if the products (fluoride and chloride) are both water-soluble and it is not possible to separate the fluorides, "dissolution" may be used, for example by using alcohol instead of water.
The solvent in the process must be selected appropriately.

(Example 1) A lid was attached to the top, and an inlet and an outlet for Ar gas to create an inert atmosphere inside and prevent oxidation of the melt;
A cylindrical container made of quartz with a temperature needle (inner diameter 100 m)
350 g of magnesium chloride was placed in a container (m, height 200 m5+), and the entire container was placed in a resistance heating furnace and heated to 800° C., which is higher than the melting point of magnesium chloride (714° C.). After the magnesium chloride was sufficiently melted, 100 g of calcium fluoride was gradually added to react with the magnesium chloride in a molten state.

After that, the plums were gradually cooled to room temperature, and the solidified salt obtained was thoroughly washed with water and filtered to dissolve and remove the unreacted magnesium chloride and calcium chloride produced by the reaction, and the magnesium chloride was separated. did.

Since magnesium oxide was detected in this magnesium fluoride, it was washed with acetic acid (5%), further washed with water, and then dried at 105°C. As a result, 75 g of magnesium fluoride (purity = 98% or more) could be obtained.

(Example 2) Using the same container as in Example 1, magnesium chloride 350
A mixture of 250 g of calcium chloride and 250 g of calcium chloride was melted at 800°C.
0 g was gradually added to react with magnesium chloride in a molten state.

In this case, the melting of calcium fluoride was faster than in Example 1, and the time from the start of adding calcium fluoride to the end of the reaction was about 1/3 that of Example 1.

The subsequent treatment was carried out in the same manner as in Example 1, and 190 g of magnesium fluoride (purity: 98% or more) could be obtained.

(Effects of the Invention) According to the method of the present invention, a desired fluoride can be obtained by reacting raw materials in a molten state. It is not difficult to operate, does not require special environmental measures, and does not require expensive raw materials, so it has great practical value.

[Brief explanation of drawings]

1 and 2 are schematic process diagrams showing an example of the manufacturing process of magnesium fluoride according to the method of the present invention. FIG. 1 is a process diagram of A, and FIG. 2 is a diagram of process B.

Claims (2)

[Claims] (1) A method of producing a fluoride characterized by reacting a chloride of an element with a small ionization tendency with a fluoride of an element showing a larger ionization tendency than the element in a molten state to obtain a fluoride of an element with a small ionization tendency. Production method. (2) Mix the chloride of an element with a small ionization tendency with the chloride of an element with a larger ionization tendency than this element, and react with the fluoride of the element with a larger ionization tendency in the molten state. A method for producing fluoride, characterized by obtaining elemental fluoride. (3) A method for producing magnesium fluoride, which comprises reacting magnesium chloride with calcium fluoride in a molten state.