KR101037128B1 - Method of reforming inner surface of reactor for manufacturing sponge titanium having high purity - Google Patents

Abstract

The present invention relates to a reactor internal surface modification method for producing high purity sponge titanium, specifically the step of charging a low quality sponge titanium at the bottom of the reactor (step 1); Sealing the reactor and heating while maintaining a vacuum (step 2); Cooling the reactor to room temperature while maintaining a vacuum (step 3); And maintaining the atmospheric pressure by injecting air into the reactor at room temperature, and then removing the sponge titanium (step 4). According to the method of the present invention, the inner surface of the reactor is alloyed with titanium to improve the corrosion resistance, and most of the elemental components present on the inner surface of the reactor contacted during the production of sponge titanium are substituted with titanium so that the surface portion is corrosion resistant in the existing iron alloy state. Since the modification is made to the more excellent iron-titanium alloy state, it is possible to prevent the inflow of Fe, Ni, Cr during the sponge titanium manufacturing process can improve the purity of sponge titanium.

High Purity Sponge Titanium, Reactor, Surface Modification

Description

Method of reforming inner surface of reactor for manufacturing sponge titanium having high purity

The present invention relates to a reactor internal surface modification method for producing high purity sponge titanium.

Titanium (Ti) is the fourth most abundant element after aluminum (Al), iron (Fe), and magnesium (Mg) among the metal elements constituting the earth's crust, and mostly exists in the form of titanium oxide (TiO ₂ ). Therefore, in order to prepare titanium, ore containing 50 to 90% of titanium oxide is reacted with chlorine gas (Cl ₂ ) to form titanium chloride (TiCl ₄ ), which is purified and then reduced to magnesium or sodium (Na). do. Titanium made in this way is called sponge titanium, so it is called sponge titanium.

Conventional industrial sponge titanium production method uses a process based on the chemical reaction of Scheme 1.

TiCl ₄ (g) + Mg (l) → Ti (s) + MgCl ₂ (l)

Specifically, when liquid titanium chloride [TiCl ₄ (l)] is supplied into liquid magnesium [Mg (l)] at 850 to 900 ° C., liquid titanium chloride vaporized at about 130 ° C. is rapidly vaporized, and vaporized titanium chloride is vaporized. [TiCl ₄ (g)] is reacted with liquid magnesium [Mg (l)] to be reduced to solid titanium [Ti (s)]. At this time, titanium is present in the form of a sponge in a mixture of excess liquid magnesium and liquid magnesium chloride [MgCl ₂ (l)]. Thereafter, liquid magnesium and liquid magnesium chloride are removed, and the liquid magnesium and liquid magnesium chloride remaining on the surface of the titanium and the inner wall of the reactor are evaporated and evaporated by vacuum at 900 to 1100 ° C., so that only pure metal titanium remains and a sponge Titanium production is complete.

Sponge titanium produced through the above process contains 0.1 to 0.5% by weight of magnesium (in the form of Mg or MgO) and 0.1 to 0.7% by weight of chlorine as main impurities, and other possible impurities include iron (Fe), Manganese (Mn), oxygen (O), carbon (C) and the like is present, the total of these is 0.3 to 0.7% by weight. That is, the purity of the sponge titanium usually produced is in the range of 98.0 to 99.8%.

Conventional sponge titanium production method is shown in Figure 1 ,

Supplying titanium chloride (TiCl ₄ ) into the reactor 51 and reacting with liquid magnesium to reduce the sponge to sponge titanium 50;

A second step (S2) of solidifying by removing the liquid magnesium and the liquid magnesium chloride in the reactor 51 in an upward or falling type;

A third step (S3) of cooling the reactor 51 to room temperature in an inert atmosphere and then separating it;

After removing the lid on the top of the reactor 51 and installing the vacuum extractor 60 to which the cooling water device 60 is attached, the reactor 51 is heated to about 1000 ° C., and the residual magnesium and residual chloride by vacuum treatment. It consists of a 4th process (S4) which removes magnesium.

Titanium chloride is fed into the stored reactor 51 with liquid magnesium at 850-900 ° C. to react with liquid magnesium to produce metal titanium and magnesium chloride. That is, the titanium chloride is reduced to the metal titanium 50 in the form of a sponge. At this time, the liquid magnesium chloride produced through the reaction of the excess liquid magnesium and titanium chloride not reacted with titanium chloride coexist in the reactor. Therefore, the liquid magnesium and the liquid magnesium chloride in the reactor 51 are removed in an upward or falling form, and the liquid magnesium and the liquid magnesium chloride removed in the reactor 51 are cooled and solidified.

Next, an inert gas such as argon is injected into the reactor 51 and cooled to room temperature under an inert atmosphere, and only a portion of the reactor 51 is separated from the entire apparatus. Subsequently, the lid provided at the upper portion of the reactor 51 is removed and a vacuum extractor 60 having a cooling water device 61 is installed at the upper end of the reactor 51. The reactor 51 is heated to about 1000 ° C. to vaporize and remove magnesium and magnesium chloride remaining on the surface of the metal titanium and the inner wall of the reactor 51 to obtain pure sponge titanium 50.

On the other hand, as the industrial reactor 51 used in the production of the sponge titanium, mild iron (Mild Steel), Fe-Ni-Cr-based SUS 3XX alloy or Fe-Cr-based SUS 4XX alloy is used. In this case, the mild steel is cheap and there is no Ni, Cr contamination source, but the corrosion resistance is low, there is a problem that the replacement cycle is short, excellent corrosion resistance is mainly used SUS alloy.

However, when sponge titanium is formed in the reactor made of SUS alloy, it is in contact with the inner wall of the reactor, where a high temperature reaction environment (for example, 830-870 ℃ in the sponge titanium reduction process, 950-1000 ℃ in the vacuum extraction) Due to the good corrosion resistance at SUS alloy, although the amount is small, Fe, Ni, Cr elements of the reactor inner wall diffuses into the titanium contaminates the titanium has a problem that the purity of sponge titanium is lowered.

Therefore, the inventors of the present invention, while studying a method of producing a high purity sponge titanium by preventing the diffusion of Fe, Ni, Cr elements into the titanium from the inner wall of the reactor at an economical method, using a low-quality sponge titanium with a relatively low purity The present invention was completed by recognizing that modification of the inner surface of the reactor can prevent contamination of titanium and improve corrosion resistance inside the reactor.

It is an object of the present invention to provide a reactor internal surface modification method using low quality sponge titanium for producing high purity sponge titanium.

It is another object of the present invention to provide a reactor for producing sponge titanium whose inner surface is modified by the reforming method.

Still another object of the present invention is to provide a method for improving the purity of sponge titanium by the above modification method.

Another object of the present invention is to provide a high-purity sponge titanium produced by the reactor for producing sponge titanium with the inner surface modified.

In order to achieve the above object, the present invention

Charging low quality sponge titanium having a purity of 98% or less at the bottom of the reactor (step 1);

Sealing the reactor and heating while maintaining a vacuum (step 2);

Cooling the reactor to room temperature while maintaining a vacuum (step 3); And

Injecting air into the reactor at room temperature to maintain the atmospheric pressure, there is provided a method of reforming the inner surface of the sponge titanium production reactor comprising the step of removing the sponge titanium (step 4).

In addition, the present invention provides a reactor for producing sponge titanium, the inner surface of which is modified by the reforming method.

Furthermore, the present invention provides a method for improving the purity of sponge titanium by the above modification method.

In addition, the present invention provides a high-purity sponge titanium produced by the reactor for producing sponge titanium with the inner surface modified.

According to the method of the present invention, the inner surface of the reactor is alloyed with titanium to improve the corrosion resistance, and most of the elemental components present on the inner surface of the reactor contacted during the production of sponge titanium are substituted with titanium so that the surface portion is corrosion resistant in the existing iron alloy state. Since the modification is made to the more excellent iron-titanium alloy state, it is possible to prevent the inflow of Fe, Ni, Cr during the sponge titanium manufacturing process can improve the purity of sponge titanium.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention

Charging low quality sponge titanium having a purity of 98% or less at the bottom of the reactor (step 1);

Sealing the reactor and heating while maintaining a vacuum (step 2);

Cooling the reactor to room temperature while maintaining a vacuum (step 3); And

Injecting air into the reactor at room temperature to maintain the atmospheric pressure, there is provided a method of reforming the inner surface of the sponge titanium production reactor comprising the step of removing the sponge titanium (step 4).

Step 1 is a step of charging a low quality sponge titanium at the bottom of the reactor.

Generally, when sponge titanium is manufactured, the surface area of 1 ~ 2 inch is low as 97 ~ 98% due to the inflow of Fe, Ni, Cr, etc. inside the reactor, so it cannot be used as an industrial material and deoxidizer for steelmaking. It is used for a separate purpose and is very cheap. Therefore, titanium used for reactor surface modification is preferably used, but not limited to, low quality sponge titanium.

The titanium is charged into the iron container and charged to the bottom of the reactor.

In this case, the loading amount of titanium is preferably 1/4 to 1/2 of the total volume of the reactor. If the loading amount of titanium is less than 1/4 of the total volume of the reactor, there is a problem in that the reforming efficiency is lowered.

Next, step 2 is a step of heating the reactor while keeping it closed and vacuum.

After charging the titanium, the reactor is sealed and then the inside of the reactor is maintained in a vacuum state using a vacuum pump. In this case, the vacuum pump used may be a mechanical or diffusion vacuum pump, but is not limited thereto.

Titanium alloying takes place on the inner wall of the reactor by heating it in a vacuum maintained reactor and reacting some of the titanium elements from the surface sponge titanium to react with the inner wall of the reactor. At this time, the heating process is preferably performed for 10 to 30 hours at 900 ~ 1100 ℃.

Next, step 3 is a step of cooling the reactor to room temperature while maintaining the vacuum state.

After the heat treatment for titanium alloying the inner wall of the reactor, the heating source is stopped and gradually cooled to room temperature while maintaining a vacuum.

Next, step 4 is to inject air into the reactor at room temperature to maintain the atmospheric pressure, and then remove the sponge titanium.

After the reactor is cooled to room temperature, air is injected into the reactor to maintain atmospheric pressure. Then, the lid is opened and the iron net is raised to collect the remaining sponge.

In addition, the present invention provides a method for improving the corrosion resistance inside the reactor by using the internal surface modification method of the sponge titanium production reactor.

Furthermore, the present invention provides a reactor in which the inner surface is modified by the reforming method.

In addition, the present invention provides a method for improving the purity of sponge titanium comprising the step of producing sponge titanium in the reactor in which the inner surface is modified by the reforming method.

Furthermore, the present invention provides a high-purity sponge titanium produced by the reactor in which the inner surface is modified by the reforming method.

According to the method of the present invention, the inner surface of the reactor is alloyed with titanium to improve corrosion resistance, and most of the elemental components present on the inner surface of the reactor contacted during the production of sponge titanium are substituted with titanium to prevent the inflow of Fe, Ni, and Cr. As a result, the purity of sponge titanium can be improved.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. The following examples are only presented to aid the understanding of the present invention, and the present invention is not limited to the following examples.

< Example > Sponge  Internal surface modification of titanium manufacturing reactor

The iron net was put into a self-assembled sponge titanium reactor (SUS304, inner diameter 430 mm, height 1000 mm), and low-quality sponge titanium was charged into the iron net by about one third of the reactor volume. After that, the reactor lid was closed and the inside of the reactor was vacuumed using a vacuum pump, and the inside surface of the reactor was titanium alloyed by heating at about 1000 ° C. for 20 hours in an electric furnace. Next, the reactor was cooled to room temperature by furnace cooling, and then air was added to maintain the inside of the reactor at atmospheric pressure. Then, the inner surface of the reactor was modified by titanium alloying by opening the reactor lid to remove the iron and collecting the remaining titanium.

< Experimental Example  1> Sponge  Purity Measurement of Titanium

In order to determine the effect of the internal surface modification of the reactor according to the present invention on the purity of the sponge titanium was carried out the following experiment.

According to the embodiment, the purity of the sponge titanium produced in the reactor inner surface modified reactor and the sponge titanium produced reactor without surface modification was measured using an Inductively Coupled Plasma (ICP) component analyzer and an elemental analyzer. It was obtained by measuring impurity components, and the results measured by inches while entering from the surface portion are shown in Table 1.

Sponge titanium inside Sponge Titanium Purity (%) Example (Surface Modification) No surface modification 1 inch 98.5 96.0 2 inches 99.3 98.7 3 inches 99.7 99.5 4 inches 99.8 99.8

As shown in Table 1, it can be seen that the reactor internal surface modification according to the present invention broadens the range of high purity sponge titanium during sponge titanium production.

In addition, regardless of the reactor type, the sum of oxygen, nitrogen, and carbon concentrations increased from about 0.1% to about 0.6% from the surface of the sponge titanium to the inside due to the difference in porosity of the parts of the sponge titanium. The concentrations of Mg and Cl ranged from 0.05 to 0.1% in total regardless of reactor type and site. On the other hand, in the case of surface modification, the total concentration of impurity components of Fe, Ni and Cr was controlled to be lower than 0.1% depending on the position.

< Experimental Example  2> Corrosion resistance measurement of reactor

In order to determine the effect of the inner surface modification of the reactor on the corrosion resistance of the reactor was carried out as follows.

Through the examples, the corrosion resistance of the sponge titanium production reactor in which the inner surface of the reactor was modified and the sponge titanium production reactor without the surface modification was measured.

Specifically, the surface of the modified sponge titanium production reactor with the inner surface modified and the sponge titanium production reactor without the surface modification were cut to a size of 15 × 25 × 0.7 mm to prepare a corrosion specimen, and then mechanically polished to grid 1200, followed by hydrofluoric acid ( HF): nitric acid: water was immersed in a solution having a volume ratio of 10:45:50 to remove impurities on the surface and defects present on the surface. The surface area and initial weight were measured immediately before the surface-treated alloy was placed in an autoclave. Then, the specimen loaded in an autoclave having 360 ° C. water and 400 ° C. (10.3 MPa) steam atmosphere was oxidized and corroded for 500 days and 400 days, respectively, and then the weight of the specimen was measured to quantitatively evaluate the degree of corrosion. It was. The corrosion test results are shown in Table 2.

division 360 ℃ water, 500 days corrosion
(mg / dm ² ) 400 ℃ water vapor, 400 days corrosion
(mg / dm ² ) Example (Surface Modification) 102 138 No surface modification 130 180

As shown in Table 2, specimens of reactors with internal surface modifications according to the present invention exhibited a corrosion degree of water of 102 mg / dm ² , which is lower than reactors without surface modifications (130 mg / dm ² ). It can be seen that, even in the degree of corrosion of water vapor, the inner surface-modified reactor specimen is 138 mg / dm ² , indicating that the degree of corrosion is lower than that of the reactor without surface modification (180 mg / dm ² ). From this it can be seen that the corrosion resistance of the reactor to modify the inner surface is increased according to the present invention.

Therefore, in the reactor internal surface modification method according to the present invention, the inner surface of the reactor is alloyed with titanium to improve corrosion resistance, and most of the elemental components present on the inner surface of the reactor contacted during the production of sponge titanium are substituted with titanium, so that the surface portion is conventional. Since the modification is made to the iron-titanium alloy state having better corrosion resistance in the iron-based alloy state, it is possible to prevent the inflow of Fe, Ni, Cr during the sponge titanium manufacturing process can improve the purity of sponge titanium.

1 is a process diagram schematically showing a conventional method for producing sponge titanium.

Claims (8)

Charging low quality sponge titanium having a purity of 98% or less at the bottom of the reactor (step 1); Sealing the reactor and heating while maintaining a vacuum (step 2); Cooling the reactor to room temperature while maintaining a vacuum (step 3); And Injecting air into the reactor at room temperature to maintain the atmospheric pressure, and then removing the sponge titanium (step 4) The internal surface modification method of the sponge titanium production reactor. The method of claim 1, wherein the charge amount of the sponge titanium of the low quality surface portion of step 1 is 1/4 to 1/2 of the total volume of the reactor. The method of claim 1, wherein the heating of step 2 is carried out at 900 ~ 1100 ℃ for 10 to 30 hours, characterized in that the internal surface modification method of the sponge titanium production reactor. The method of claim 1, wherein the inner surface modification of the reactor is a titanium element is partially evaporated to react with the inner wall of the reactor to cause titanium alloying on the inner wall of the reactor. Charging low quality sponge titanium having a purity of 98% or less at the bottom of the reactor (step 1); Sealing the reactor and heating while maintaining a vacuum (step 2); Cooling the reactor to room temperature while maintaining a vacuum (step 3); And And maintaining the atmospheric pressure by injecting air into the reactor at room temperature, and then removing the sponge titanium (step 4). Reactor for producing sponge titanium in which the inner surface of the reactor is modified by the method of claim 1 A method for improving the purity of sponge titanium comprising producing sponge titanium in a reactor having an interior surface modified according to claim 6. Sponge titanium of high purity produced by a reactor for producing sponge titanium, wherein the inner surface of claim 6 is modified.

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