JPH0226828A - Production of titanium tetrachloride - Google Patents

Abstract

PURPOSE:To discharge only undesirable, non-conductive and difficultly reactable substance at high efficiency in the chlorination of raw material contg. Ti and to prevent the accumulation thereof by re-charging only conductive particles separated from fluidized particles drawn out from a fluid chlorination furnace by electrostatic concentration. CONSTITUTION:The raw material contg. Ti such as synthetic rutile and coke are charged in the fluid chlorination furnace 1 lined the inside surface thereof with refractory 2. A fluidized bed 3 is formed by introducing Cl2 gas from the underpart of the furnace 1 and TiCl4 gas is discharged form the upper part of the furnace 1. On the other hand, a part of particles forming the fluidized bed 3 is discharged outside of the furnace, sent to an electrostatic concentrator 5 after cooling 4 to 90-250 deg.C to separate into conductive particles and non-conductive ones. Then, the conductive particles are re-charged to the furnace 1 together with the raw material contg. Ti and coke. In the electrostatic concentration, the voltage between both electrodes is preferably 5-50kV. According to the method above-mentioned, the accumulation in the furnace of non-conductive substance, difficultly reactable substance, is prevented and the occupancy rate of the conductive substance, reactable substance, in the furnace, is increased, and thereby, the reactivity in the chlorination above-mentioned can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing titanium tetrachloride by chlorinating titanium-containing raw materials such as titanium-containing ores and synthetic rutile.

[Conventional technology]

Titanium tetrachloride, which is a raw material for producing titanium metal, is produced by chlorinating titanium-containing raw materials such as titanium-containing ores and synthetic rutile. In this case, the titanium-containing raw material and petroleum coke are heated to 950 to 1000
Fluidization is carried out at a temperature of 70°C. The bed in which particles are fluidized in the furnace is called a fluidized bed, and the reaction in the fluidized bed is called a fluidized reaction.

When the flow reaction continues in such a titanium tetrachloride production method, substances with relatively slow reaction rates among the substances contained in the raw materials and the eroded parts of the lining material,
That is, T i O! in the temperature range of 950 to 1070″C!
, SiO□, Zrot, An, which has a slower reaction rate than C
! Substances such as i 0s (hereinafter referred to as refractory substances) gradually accumulate in the fluidized bed, and in some cases these refractory substances may exceed 50% of the weight of the fluidized bed.

When the amount of poorly reactive substances increases in the fluidized bed, the concentration of T i Ox and C (hereinafter referred to as reactive substances), which have a high reaction rate, becomes relatively low, which worsens the reactivity.

As countermeasures against this problem, raising the reaction temperature and increasing the height of the fluidized bed are known. Increasing the reaction temperature promotes the reaction of poorly reacting substances and suppresses the accumulation of difficultly reacting substances. When the height of the fluidized bed is increased, the proportion of poorly reacting substances in the fluidized bed is relatively reduced, and deterioration of reactivity is suppressed. However, while these measures suppress the deterioration of reactivity due to the accumulation of refractory substances, they cause the following disadvantages.

[Problem to be solved by the invention] When coke is burned in an attempt to raise the reaction temperature,
Since coke is consumed and the balance of carbon dioxide gas is biased towards CO, the amount of coke consumed increases and the production cost of titanium tetrachloride increases. Also, the erosion of the lining material of the chlorination furnace increases. When the height of the fluidized bed is increased, the increased height of the fluidized bed comes into contact with the new lining material, which causes additional erosion and new reactivity! yJ quality is fed into the fluidized bed. Furthermore, with the passage of time, refractory substances in the raw materials accumulate in the same way. therefore,
You won't get the desired effect.

If refractory substances are not sufficiently restricted in the fluidized bed,
Since the amount of raw material contained in the fluidized bed decreases, there is a problem that there is not enough spare time for operating the chlorination furnace, and the operator is forced to strictly manage the operation. In addition, as the operation progresses, the refractory substances gradually react, but the reaction rate is extremely slow at normal operating temperatures.

In view of this situation, the present invention aims to provide a method for producing titanium tetrachloride that suppresses the accumulation of refractory substances without increasing coke consumption or fluidized bed height.

[Means for solving the problem] In the production of titanium tetrachloride by fluidized reaction, if it is possible to separate the poorly reactive substances and reactive substances accumulated in the fluidized bed, only the hardly reactive substances can be removed from the fluidized bed, It becomes possible to prevent the accumulation. The present inventors used electrostatic beneficiation to collect particles that form a fluidized bed, since refractory substances are generally non-conductive and can be clearly distinguished from conductive reactive substances based on their electrical conductivity. It has been found that by separating conductive and non-conductive substances, only non-conductive and difficult-to-react substances can be discharged with high efficiency and their accumulation can be prevented.

The method of the present invention was developed based on such knowledge,
In the method of manufacturing titanium tetrachloride by chlorinating titanium-containing raw materials in a fluidized chlorination furnace, the particles that form the fluidized bed in the fluidized chlorination furnace are extracted outside the furnace, and the extracted particles are electrostatically beneficent to form a conductive material. This method prevents the accumulation of refractory substances in the furnace by separating the particles from non-conductive particles and excluding the non-conductive particles while reinjecting the conductive particles into the furnace. .

[For production]

Electrostatic beneficiation is the conventional method that when a substance is given a surface charge before or when it enters an electrostatic field, it will be repelled to certain electrodes and attracted to other electrodes depending on the sign of the charge. However, recently it has become possible to sort ores by taking advantage of the fact that a similar phenomenon occurs not only due to surface charge but also due to differences in the electrical conductivity of particles.

By applying electrostatic beneficiation to the particles that form the fluidized bed in the fluidized chlorination furnace, separating them into conductive and non-conductive particles, and reinjecting the conductive particles into the furnace. Only non-reactive substances are extracted, and accumulation of non-reactive substances in the furnace is prevented.

[Example] FIG. 1 is a flow diagram showing specific steps of the method of the present invention.

The inner surface of the fluidized chlorination furnace 1 is lined with a refractory 2. A titanium-containing raw material such as synthetic rutile and coke are charged into the chlorination furnace 1. In this state, a fluidized bed 3 is formed by injecting chlorine gas from above the furnace, and titanium tetrachloride gas is taken out from above the furnace.

On the other hand, some of the particles forming the fluidized bed 3 are extracted outside the furnace, sent to the heat exchanger 4, cooled, and then sent to the electrostatic separator 5 through the outlet pipe 6. and non-conductive. A very small amount of N2 or Ar gas is passed through the outlet pipe 6 in order to return only the furnace gas accompanying the extracted particles into the furnace.

The reason why cooling is performed before performing electrostatic beneficiation is because the particle temperature in the furnace is about 1000°C, and the ore beneficiation equipment must have a special heat-resistant structure. Cooling temperature is 250”C
At temperatures above 90°C, a heat-resistant structure is required, and at temperatures below 90°C, a very small amount of residual chloride will adhere to the particle surface, which will adsorb moisture in the air, making all particles conductive and reducing separation efficiency. A range of 90 to 250°C is preferred.

In electrostatic beneficiation, the interelectrode voltage is preferably 5 to 50 kV. If it is less than 5 kV, the separation efficiency will deteriorate and the
kv requires a large and expensive device.

Among the particles subjected to electrostatic beneficiation, conductive particles are reinjected into the fluidized chlorination furnace 1 together with the titanium-containing raw material and coke. Non-conductive materials are either discarded as is or are discarded after undergoing one or more re-electrostatic beneficiations. Re-electrostatic beneficiation increases the separation efficiency of conductive and non-conductive particles and reduces the amount of conductive particles that are discarded along with the non-conductive particles. For re-electrostatic ore separation, the ore concentrator used for the first electrostatic ore separation may be used, or a different ore separator may be used.

Next, we will explain the implementation results. In both implementation results, titanium tetrachloride was produced by fluidizing titanium-containing ore and petroleum coke at 1000'C with chlorine gas from the bottom in a chlorine furnace with a metal cylindrical container lined with a refractory. It was done while

O Implementation Result 1 Particles are continuously extracted from the fluidized bed 3 in the chlorination furnace 1 at a rate of 80 kg/Hr, supplied to the heat exchanger 4, and heated to 200°C.
After being cooled to 100%, it was fed to electrostatic beneficiation. The interelectrode voltage in electrostatic beneficiation was 18 kV. As a result, the particles are 72
．． It was separated into 6% conductive particles and 27.4% non-conductive particles. The composition of each particle is shown in Table 2.

Table 2 Most of the conductive particles are reactive substances (TiO□, C)
It is. 3/4 of the non-conductive particles are made up of poorly reactive substances (S
iOZ, Al-t03, Zr0z, etc.).

By reintroducing conductive particles into the chlorination furnace and discarding non-conductive particles, it is possible to prevent the accumulation of refractory substances in the furnace without raising the reaction temperature or fluidized bed height more than necessary. Prevented.

At the stage when the hardly reactive substance accounted for 25 wt% in the flow rate, particles were extracted and separated under the above conditions to reduce the content of the hardly reactive substance to 5 wt%. This allowed the reaction to continue at the same reaction temperature of 990°C. Also,
This operation also suppressed erosion of the furnace lining material and extended the furnace life by about 1.5 times.

O Result 2 The operation was carried out under the same conditions as Result 1 except that the particles were cooled to room temperature in the heat exchanger 4. The separation efficiency between conductive particles and non-conductive particles and the composition of each particle were almost the same as in Example Results 1, as shown in Table 3. However, if the particles are cooled to room temperature, there is a concern that chlorides will adhere to the particle surface, changing the surface conductivity and reducing the separation efficiency, so it is recommended that the cooling temperature be 90°C or higher. good.

Table 3 O Implementation Results 3 The non-conductive particles separated and extracted in Implementation Results 1 were subjected to electrostatic beneficiation again. The interelectrode voltage was 20 kV, and the particle feed rate in the electrostatic separator was 120 kg/Hr.

As shown in Table 4, the results show that the non-conductive particles were 19
．． It was separated into 3% conductive particles and 80.7% non-conductive particles. As a result, the concentration of the hardly reactive substance in the non-conductive particles is further increased by electrostatic beneficiation multiple times, and the amount of the reactive substance discarded together with the non-conductive particles is reduced.

Since there is no need for a table, coke is not consumed unnecessarily, and since there is no need to increase the height of the fluidized bed, erosion of the lining material is suppressed, making it possible to improve economic efficiency from both of these aspects. becomes.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram illustrating typical steps of the method of the present invention. In the figure, 1: fluidized chlorination furnace, 3: fluidized bed, 5: electrostatic separator. [Effect of the invention]

Claims (1)

[Claims] 1. In a method for producing titanium tetrachloride by chlorinating titanium-containing raw materials in a fluidized chlorination furnace, the particles that form the fluidized bed in the fluidized chlorination furnace are extracted outside the furnace, and the extracted particles are electrostatically sorted to make them conductive. separated into conductive and non-conductive,
A method for producing titanium tetrachloride, characterized in that accumulation of refractory substances in the furnace is prevented by excluding non-conductive particles while reinjecting conductive particles into the furnace.