JPS6364506B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing titanium metal by reacting titanium tetrachloride and a reducing metal in a reaction zone at a temperature higher than the melting point of the reducing metal and the chloride of the reducing metal. Regarding the improvement of

Conventionally, the so-called Hunter method, Kroll method, etc. are known as methods for producing the above-mentioned titanium metal.
For example, in the Kroll method, before the start of the reaction, solid or molten magnesium, which is a reducing metal, is charged into a retort-like reaction vessel (if solid magnesium is used, it is further heated,
After raising the temperature to a temperature at which it can react with titanium tetrachloride),
Liquid titanium tetrachloride is reacted while being dropped into the reaction vessel, and the temperature of the reaction part is maintained at a temperature higher than the melting point (715°C) of magnesium chloride produced together with metallic titanium by reaction heat and/or external heating. Carry out the reaction.

Since the melting point of metallic magnesium is 650°C, metallic magnesium is also a molten body at the above temperature. In order for the titanium tetrachloride dropped from the top of the reactor to react smoothly and rapidly, magnesium, not magnesium chloride, must be present on the surface formed by both the magnesium and magnesium chloride melts (hereinafter simply referred to as the melt surface). However, direct contact with the dropped titanium tetrachloride is essential.
Since the specific gravity of molten magnesium is lower than that of molten magnesium chloride, generally at least in the early stage of the reaction, magnesium chloride sinks below the molten layer, and the molten magnesium layer floats above it, and the molten surface is mainly made up of magnesium. The reaction proceeds smoothly and rapidly. Incidentally, since the titanium produced by the reaction is heavier than both the magnesium and magnesium chloride melts, it settles at the bottom of the reaction vessel and forms a spongy layer (hereinafter this layer is referred to as a spongy titanium layer).

Since the sum of the increase in the volume of magnesium chloride and the increase in the volume of titanium as the reaction progresses is much larger than the decrease in volume due to consumption of magnesium, the total volume of the contents in the reactor increases as the reaction progresses. It is necessary to increase the amount of titanium produced per reactor volume, that is, the volumetric efficiency of the reactor, in order to improve productivity.
For this purpose, it is necessary to extract the magnesium chloride produced during the course of the reaction from the container several times or continuously.

As the reaction progresses, the deposited layer of metallic titanium (sponge-like) gradually grows upward, but in order to keep the reaction progress (reaction rate) fast, contact between magnesium and titanium tetrachloride is required. It is necessary to have good properties, and for this reason it is preferable that the surface of the magnesium layer be located above the titanium sponge layer. If the surface of the magnesium layer is located at a significantly lower level than the titanium sponge layer, the titanium tetrachloride must penetrate through the pores of the titanium sponge before contacting and reacting with the magnesium, resulting in an extremely slow reaction rate.

Therefore, it is necessary to calculate and determine the above-mentioned extraction timing and extraction amount of magnesium chloride so that the surface of the magnesium layer floating on the magnesium chloride layer is near or above the surface of the titanium sponge layer. However, even if the position of the magnesium layer surface is adjusted in this way, the magnesium chloride produced by the reaction on the magnesium surface will descend through the pores of the titanium sponge layer, and the magnesium will rise through the pores of the titanium sponge layer. Must.

In this way, the replacement of magnesium with magnesium chloride must be carried out through the pores of the titanium sponge layer, and as the deposited layer of titanium sponge grows, the rate of replacement between the two decreases, so it is originally necessary to replace magnesium with magnesium chloride above the titanium sponge layer. Alternatively, the magnesium layer, which should be floating in the vicinity, remains in the sponge titanium layer, and instead, a situation occurs in which magnesium chloride, which should be precipitated, floats above the sponge titanium layer. Under such conditions, titanium tetrachloride cannot of course come into contact with magnesium and the reaction stops.

The reaction is carried out by appropriately selecting the shape of the reactor, the amount of magnesium charged, the timing and amount of magnesium chloride to be extracted, etc., in order to maximize the efficiency of operation such as the volumetric efficiency of the reactor, reaction rate, and utilization rate of magnesium. Even if the amount of magnesium is reduced, for example, when about 60% of the amount of magnesium charged has reacted, the substitution of magnesium and magnesium chloride usually begins to deteriorate and the reaction rate begins to decrease. The problem of a reduction in the reaction rate in the latter stage of the reaction due to poor substitution of magnesium and magnesium chloride can be cited as the first drawback of the conventional method.

Another reason why magnesium becomes impossible to float and the reaction stops is that magnesium is trapped in the pores of the spongy titanium sediment layer.
The reason is that it cannot float to the surface of the solution. In other words, the reaction between magnesium and titanium tetrachloride takes place near the surface of the magnesium, and the titanium sponge formed at this location gradually settles to the bottom of the vessel. Even if the magnesium contained in the pores of this sponge is well replaced with magnesium chloride, it cannot float to the surface, resulting in a loss that cannot react with titanium tetrachloride. This is a major reason why in the conventional method, the reaction amount relative to the initially charged amount of magnesium, that is, the magnesium utilization rate, cannot be improved beyond about 70 to 80%. The problem of low magnesium utilization can be cited as the second drawback of the conventional method.

Next, in the early stage of the reaction in the conventional method, the magnesium layer is in a state where it can come into good contact with titanium tetrachloride, so by increasing the dropping rate of titanium tetrachloride, the reaction rate itself can be increased almost without limit. When the reaction rate is increased, the reaction between magnesium and titanium tetrachloride generates a large amount of reaction heat, and the temperature of the reactor rises extremely quickly. Reactor walls are usually made of iron or iron-based alloys for economic reasons, but the eutectic point of titanium and iron is approximately
Since the temperature is 1050°C, if the temperature of the reactor wall exceeds this temperature, the reactor wall and the titanium produced will undergo eutectic melting. Rapid reaction rates leading to exotherms above this temperature cannot therefore be carried out. This restriction on the reaction rate at the initial stage of the reaction can be cited as the third drawback of the conventional method.

The present invention was made in order to improve the drawbacks of such conventional methods, and does not reduce the reaction rate in the late stage of the reaction seen in the conventional methods, shortens the reaction time, and therefore has high productivity. Energy consumption is drastically reduced, and the utilization rate of reducing metals is high.
Another object of the present invention is to provide a method for producing titanium metal in which the reaction temperature can be easily controlled.

That is, the present invention provides a method for producing metallic titanium by reducing titanium tetrachloride with a reducing metal at a temperature equal to or higher than the melting point of the reducing metal and the chloride of the reducing metal. The body is brought into contact with titanium tetrachloride in the form of droplets, the droplets of the molten substance of the reducing metal are cooled and solidified, and a part of the titanium tetrachloride is partially reduced, thereby reducing the granular solid and part of the reducing metal. The present invention provides a method for producing titanium metal, which is characterized in that a titanium tetrachloride slurry containing a reduction product is prepared, and the slurry is reacted while being supplied to a reaction zone.

Examples of reducing metals used in the present invention include magnesium, sodium, lithium, potassium,
Examples include calcium, but magnesium is most preferred.

Partial reduction products obtained by partially reducing a portion of titanium tetrachloride by contacting titanium tetrachloride with a droplet of the melt of the reducible metal of the present invention include titanium trichloride, titanium dichloride, and titanium tetrachloride. It is a metal chloride.

There is no particular restriction on bringing the molten reducing metal into droplets and bringing it into contact with titanium tetrachloride as long as a granular solid of the reducing metal having the desired particle size can be obtained, but dropping methods, centrifugal spraying methods can be used. The following means can be used as appropriate.

In the present invention, when supplying the titanium tetrachloride slurry containing the granular solid of the reducible metal and the partial reduction product to the reaction zone, in particular, as long as the contact between the two can be made good and the reaction can be carried out quickly. Although there is no restriction, it is preferable to supply the solution directly to the solution surface from above the reaction zone because the reaction can be carried out smoothly and quickly.

Before supplying the titanium tetrachloride slurry of the present invention to the reaction zone and starting the reaction, a part of the reducing metal or a mixture of the reducing metal and the chloride may be charged into the reaction zone in advance. In this case, the reaction starts smoothly and is therefore preferred.

According to the method of the present invention, a titanium tetrachloride slurry containing the reducing granular solid and the partial reduction product obtained by solidifying the droplets of the melt of the reducing metal is dissolved from above the reaction zone. Since the reaction is carried out while being directly supplied to the surface, the amount of reaction per unit time and therefore the productivity can be significantly increased without a sudden or local temperature increase in the reaction temperature.

In addition, the powdery solid of the reducing metal is uniformly dispersed in the titanium tetrachloride slurry, and the titanium tetrachloride slurry is rapidly and smoothly supplied directly to the molten surface above the titanium sponge layer. As the reaction progresses, the amount of reducing metal that is trapped in the pores of the titanium sponge layer and does not contribute to the reaction is extremely small, and therefore the utilization rate of reducing metal is greatly increased.

According to the method of the present invention, since the reducing metal is directly supplied as a solid to the reaction zone, the heat content is lower than that in the molten state in the conventional method, and the temperature increase due to the reaction heat is alleviated. This has the effect of increasing production volume per hour, that is, productivity.
For example, solid magnesium has a lower temperature than molten magnesium at a reaction temperature of e.g.
Its heat content is lower by about 8.7 Kcal/mol, which is
For example, it corresponds to about 28% of the reaction heat of 31.4 kcal/mol per mol of magnesium in the reaction between titanium tetrachloride and magnesium at a reaction temperature of 1000°C.

Furthermore, since the titanium tetrachloride slurry contains titanium trichloride, which is a partial reduction product of titanium tetrachloride, the reaction time is lower than when titanium tetrachloride is used alone due to the partial reduction. The amount of heat generated is small.

Normally, when a liquid droplet of a molten reducing metal is brought into contact with titanium tetrachloride to partially reduce the titanium tetrachloride and the droplets of the molten substance are solidified to form a titanium tetrachloride slurry, 10% of the reducing metal is Reacts with titanium tetrachloride to form titanium trichloride and titanium dichloride.

Taking the case of reducing titanium tetrachloride with magnesium as an example, assuming that when making titanium tetrachloride slurry, 10% of the magnesium reacts and the partial reduction progresses to titanium trichloride, titanium tetrachloride is reduced with magnesium. At 1000°C, the reaction heat when reducing the above-mentioned titanium tetrachloride slurry containing titanium trichloride is lower by about 11.4 kcal/mol per mol of magnesium in the latter case, which is about 36% of the reaction heat in the former case. Equivalent to. Therefore, the third drawback of the conventional method, which is the restriction on the reaction rate caused by the temperature increase due to the reaction heat, is due to the above-mentioned difference in magnesium content and the formation of partial reduction products in the titanium tetrachloride slurry. It is reduced by the amount of reduction in reaction heat. In other words, if the amount of heat released from the reaction vessel remains the same, the reaction rate can be increased by about 64%.

When supplying the titanium tetrachloride slurry, it may be supplied continuously or intermittently, or it may be supplied for a part of the entire reaction period that is arbitrarily selected depending on the reaction conditions, and for other It is also possible to supply only titanium tetrachloride for a period of time.

According to the method of the present invention, the uniformity of the titanium tetrachloride slurry is extremely good, the reaction is carried out quickly and smoothly, and the reaction heat generated due to the presence of partial reduction products in the slurry is reduced. Therefore, the reaction rate can be significantly increased, and the production capacity can be significantly increased and the heating power can be significantly reduced.

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

Example 1 A titanium tetrachloride liquid film having a thickness of 4 mm and falling at a flow rate of 1 m/sec is formed on the wall of a spray tank having an inner diameter of 1000 mmΦ and a height of 1300 mm. Diameter 200 installed in the spray tank
Molten magnesium heated to 800℃ is supplied onto a rotating disk with a rotation speed of 400rpm, and centrifugal force atomizes the molten magnesium to 2mm or less, which is then sprayed onto the surrounding wall of the spray tank. The sprayed molten magnesium is cooled and solidified by the titanium tetrachloride liquid film. At this time, when molten magnesium and titanium tetrachloride come into contact, a portion of the titanium tetrachloride is reduced to produce lower titanium chloride and magnesium chloride, the amount of which corresponds to about 10% of the magnesium to be supplied.

The titanium tetrachloride slurry containing magnesium particles, titanium lower chloride, and magnesium chloride produced in the spray tank is pumped into a cooler and cooled, and then flows down the wall of the spray tank again. The slurry that has been supplied with magnesium in an amount corresponding to a molar ratio of titanium tetrachloride and magnesium of 1:2 is
Pump into another tank and store in a tank with a stirrer.

A supply pipe for the slurry was installed through the center of the upper lid of a reaction vessel with a steel inner cylinder set inside a steel outer cylinder, and approximately 1.5 tons of sponge was added using a reduction reaction device that can be heated electrically from the outside of the outer cylinder. produced titanium.

Put 500kg of molten magnesium into the outer cylinder and heat to 800℃.
Heat until. When the temperature reached 800℃, the titanium tetrachloride slurry was added at 8693g/min (titanium tetrachloride).
4000c.c./min, magnesium 1773g/min) into the reaction vessel from the supply pipe.

The supply of slurry was stopped approximately 15 hours after the start of the reaction.
Obtained 1570Kg of titanium sponge.

The reaction temperature was 1000℃, and the Mg excess was 1.35.
It was hot. The production amount of titanium sponge per unit time was 104.7 kg/h.

Comparative Example 1 Using the conventional method, first, before starting the reaction, the total amount of magnesium required for the reaction, 2200 kg, was charged into a reaction vessel, and after raising the temperature to 800°C, 1000 to 2100 kg of titanium tetrachloride was charged.
It was supplied at a rate of cc/min for 42 hours and reacted at 1000°C to obtain 1500 kg of titanium sponge. The Mg excess rate was 1.47, and the amount of titanium sponge produced per unit time was 35.7 Kg/h.

Claims (1)

[Scope of Claims] 1. A method for producing metallic titanium by reducing titanium tetrachloride with a reducing metal at a temperature higher than the melting point of the reducing metal and the chloride of the reducing metal. The melt is brought into contact with titanium tetrachloride in the form of droplets, the droplets of the melt of the reducing metal are cooled and solidified, and a part of the titanium tetrachloride is partially reduced, thereby forming a powdery solid of the reducing metal and a part of the titanium tetrachloride. A method for producing titanium metal, which comprises preparing a titanium tetrachloride slurry containing the partial reduction product, and causing the slurry to react while being supplied to a reaction zone. 2. The method for producing titanium metal according to claim 1, wherein the reducing metal is magnesium. 3. The method for producing titanium metal according to claim 1 or 2, wherein the titanium tetrachloride slurry is fed into the reaction zone from above. 4. The method for producing titanium metal according to any one of claims 1 to 3, wherein a part of the reducing metal is supplied to the reaction zone before supplying the titanium tetrachloride slurry. 5. Any one of claims 1 to 4, wherein the titanium tetrachloride slurry is supplied for an arbitrarily selected part of the entire reaction period, and only titanium tetrachloride is supplied for the remaining period. The method for manufacturing titanium metal described in the section.