A new process and device for preparing titanium tetrachloride suitable for the characteristics of my country's titanium resources

Abstract

This invention innovatively optimizes the design of existing boiling chlorination equipment for titanium tetrachloride production, resulting in a new process and apparatus with more rational overall structure and functionality. By adding a molten salt section with specialized functions, the process achieves uniform chlorine gas flow distribution, preheating, molten salt purification, insulation, storage, and controlled emission. It also addresses the availability of raw materials suitable for my country's titanium resources (high-calcium-magnesium-high-titanium slag). It also avoids the adverse effects of high-boiling-point chlorides accumulating in the lower portion of the boiling section, which negatively impacts continuous and stable production, thereby achieving continuous and stable production of titanium tetrachloride using high-calcium-magnesium-high-titanium slag. It also strengthens the thermodynamic and kinetic conditions for the chlorination reaction of unreacted charge material that falls to the bottom of the fluidized bed (the upper surface of the heating carrier), improving raw material utilization. Furthermore, it improves the quality of the high-boiling-point chloride salt, making it a valuable material. This represents a new process and apparatus for producing titanium tetrachloride that is suitable for my country's titanium resources.

Description

Technical Field

[0001] The invention relates to the field of industrial production of titanium dioxide and titanium sponge.

[0002] In particular, the invention relates to a device for preparing titanium tetrachloride which is suitable for the characteristics of my country's titanium resources (high calcium, magnesium and high titanium slag). Background Art

[0003] my country's titanium resources are very rich, with reserves ranking first in the world, accounting for 48% of the world's proven total reserves. Ilmenite accounts for 98% of my country's total titanium reserves, while rutile accounts for only 2%.

[0004] Ilmenite is beneficiated to obtain titanium concentrate, which is then smelted and reduced in an electric furnace to separate titanium dioxide and iron from the titanium concentrate. The resulting concentrate with a high titanium dioxide content is called high-titanium slag.

[0005] High-titanium slag is the main raw material for the industrial production of titanium tetrachloride, titanium dioxide and sponge titanium products. 90% of my country's ilmenite can only produce high-calcium-magnesium high-titanium slag products with a total calcium oxide and magnesium oxide content of about 8.5%. Only a small part of the titanium ore can produce high-titanium slag products with lower calcium and magnesium oxide content.

[0006] Boiling chlorination is the main method for industrial production of titanium tetrachloride in my country, and the high-titanium slag suitable for current boiling chlorination production is mostly smelted from a mixture of domestic and imported ores.

[0007] This process involves chlorinating a mixture of high-titanium slag and petroleum coke in a fluidized chlorine atmosphere within a fluidized furnace. It is a traditional application of fluidized bed technology in titanium tetrachloride production. Due to the intense relative motion between the solid and gas phases, mass and heat transfer is excellent, significantly enhancing production. However, this process has a major disadvantage: impurity oxides in the high-titanium slag are also chlorinated in the fluidized chlorination furnace at temperatures of 800-1000°C, producing corresponding chlorides and gases such as CO and CO₂. Chlorides with boiling points below the chlorination temperature, such as FeCl₃ (sublimed gas), AlCl₃ (sublimed gas), SiCi₃, as well as gases such as CO and CO₂, evaporate and escape the chlorination furnace along with TiCi₄. After subsequent cooling, dust collection, leaching, sedimentation, and filtration, liquid titanium tetrachloride is obtained. Chlorides with boiling points above the chlorination temperature, such as CaCl₂, MgCl₂, FeCl₂, and MnCl₂, remain in the furnace along with unreacted TiO₂ and carbon powder, forming slag. As the chlorination reaction proceeds, more and more slag is generated. These slags accumulate in the lower part of the boiling furnace, which not only occupies the effective working space of the boiling section, but also increases the resistance of chlorine gas and destroys the distribution state of chlorine gas, seriously worsening the production conditions of boiling chlorination. This forces us to discharge the slag under the conditions of stopping chlorination and stopping the material. Moreover, the higher the content of calcium and magnesium oxides in the high-titanium slag, the shorter the slag discharge cycle and the higher the slag discharge frequency. This slag discharge process will undoubtedly affect the continuity of chlorination production and may even lead to the inability to carry out production in severe cases. In view of this situation, the existing boiling chlorination production process has strict restrictions on the total amount of impurities calcium oxide and magnesium oxide in the high-titanium slag product. Initially, it cannot exceed 1%. Later, with the growth of my country's titanium tetrachloride production capacity, the demand for high-titanium slag has also increased rapidly. However, the supply of high-titanium slag products that can meet the quality requirements is seriously insufficient. This has forced us to relax the quality restrictions on high-titanium slag, and the total amount of calcium oxide and magnesium oxide has been relaxed to no more than 2.6%. Even if this type of high-titanium slag raw material is obtained, it is mostly obtained by mixing imported ore and domestic ore for smelting.

[0008] my country's existing boiling chlorination process and equipment have the following defects:

[0009] ① The characteristics of my country's titanium resources are mainly high calcium magnesium oxide. The existing high titanium slag raw materials that meet the traditional boiling chlorination production of titanium tetrachloride are mostly smelted from a mixture of domestic and imported ores;

[0010] ② In the existing boiling chlorination technology and equipment, calcium oxide and magnesium oxide react in the process to form high-boiling-point chlorides such as calcium chloride and magnesium chloride, which are retained at the bottom of the furnace and mixed with other chlorides and unreacted oxides, making the chlorination reaction unable to proceed continuously;

[0011] ③ The high-boiling point chlorides retained at the bottom of the furnace are mixed with the unreacted charge, resulting in charge loss and reducing the effective utilization rate of the charge;

[0012] ④ The high-boiling point chlorides mixed with the charge cannot be recycled due to their poor quality and become harmful solid waste, resulting in waste of valuable materials and environmental pollution. Summary of the Invention

[0013] The purpose of the present invention is to provide a new process and device for preparing titanium tetrachloride that is suitable for the characteristics of my country's titanium resources (high calcium, magnesium and high titanium slag) based on the current status of my country's titanium resources and in combination with the defects of the above-mentioned existing boiling chlorination technology and equipment, so as to improve the technical equipment level and technical and economic indicators of my country's titanium tetrachloride production.

[0014] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a device for preparing titanium tetrachloride from high-calcium-magnesium-high-titanium slag, wherein the working space of the molten salt section is filled with a heating carrier, the material of which should simultaneously meet the following conditions: (1) no chemical reaction with chlorine. (2) no pollution of materials. (3) suitable specific resistivity. (4) suitable strength. (5) good filtering performance for chloride molten salt; the shape of the heating carrier should be convenient for achieving the desired airflow distribution effect by adjusting the packing density of different areas; sufficient porosity is required between the heating carriers to ensure that there is sufficient storage space for high-boiling point chlorides; three heating electrodes are evenly arranged along the circumferential direction at the lower part of the heating carrier, and the three heating electrodes pass through the furnace shell and extend into the furnace to contact the heating carrier; a chlorine distributor is arranged on the upper part of the heating carrier, and the chlorine distributor passes through the furnace shell and the refractory lining and extends into the furnace and is distributed on the upper part of the heating carrier; a molten salt discharge port is provided at the bottom of the molten salt section, and the molten salt discharge port is discharged from the bottom surface of the furnace along the side. It passes through the refractory lining and the furnace shell and extends out of the furnace through the flow channel; the fault slag discharge port passes through the refractory lining and the furnace shell from the side wall of the upper surface of the heating carrier and extends out of the furnace through the flow channel, and the boiling section is directly above the molten salt section; a feeder is provided in the middle and upper part of the boiling section, and the feeder extends into the furnace from outside the furnace through the furnace shell and the refractory lining; above the boiling section is a transition section, and above the transition section is an expansion section. Several groups of cooling water inlet and outlet pipes are respectively provided on the upper part of the boiling section, the middle part of the boiling section and the lower part of the furnace top cover according to temperature needs. Above the expansion section is the furnace top cover, and the furnace top cover is provided with a furnace gas outlet, a mud spraying port and a titanium tetrachloride nozzle, and the furnace gas outlet is connected to the dust collecting cooler downstream of this device.

[0015] Preferably, the heating carrier is a high-quality carbon block in various forms.

[0016] Preferably, the heating electrode is a metal-high-quality graphite combination electrode with a water cooling device, and the thermocouple is inserted longitudinally from the outside to the inside to the depth of the electrode refractory lining.

[0017] Preferably, the chlorine distributor is a special steel-ceramic composite pipe fitting, and the chlorine distributor is arranged on the upper surface of the molten salt section or slightly below it.

[0018] Preferably, the heating electrode passes through the furnace shell and the refractory lining and extends into the furnace, and the portion extending into the furnace is connected to the heating carrier.

[0019] Preferably, the molten salt discharge port extends from the side wall of the furnace bottom through the refractory lining and the furnace shell through the flow channel to the outside of the furnace.

[0020] Preferably, the faulty slag discharge port extends from the side wall of the upper surface of the heating carrier through the refractory lining and the furnace shell through the flow channel to the outside of the furnace.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention innovatively optimizes the design of an existing boiling chlorination furnace device to form a device with more reasonable overall structure and functions. By designing a molten salt section with specific functions, including arranging a heating carrier, a heating electrode, a chlorine distributor and a molten salt discharge port, the device has the functions of uniform chlorine gas flow distribution and preheating, molten salt purification, heat preservation, storage and controllable discharge, thereby solving the problem of the availability of raw materials suitable for the characteristics of my country's titanium resources (high-calcium-magnesium-high-titanium slag). High-boiling-point chlorides are allowed to smoothly enter the molten salt section from the boiling section in a molten state, avoiding the adverse effects on the continuous and stable production caused by the retention and accumulation of high-boiling-point chlorides in the lower part of the boiling section, thereby achieving the continuous and stable operation of the production of titanium tetrachloride using high-calcium-magnesium-high-titanium slag by boiling chlorination. The thermodynamic and kinetic conditions for the chlorination reaction of unreacted furnace charge falling to the bottom of the boiling bed (the upper surface of the heating carrier) are strengthened, which is conducive to improving the utilization rate of raw materials. The quality of the high-boiling-point chloride salt is improved to make it a useful material. The present invention is a new process and device for preparing titanium tetrachloride by boiling chlorination suitable for the characteristics of my country's titanium resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the present invention.

[0024] In the figure: a molten salt section, b boiling section, c transition section, d expansion section, 1 mud injection port, 2 cooling water inlet pipe, 3 feeding port, 4 chlorine distributor, 5 heating electrode, 6 titanium tetrachloride nozzle, 7 furnace gas outlet pipe, 8 cooling water outlet pipe, 9 fault slag discharge port, 10 molten salt discharge port, 11 expansion section refractory lining, 12 boiling section refractory lining, 13 molten salt section refractory lining, 14 heating carrier. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] Please refer to the attached figure, which shows a device for preparing titanium tetrachloride from high calcium, magnesium and titanium slag, including a molten salt section a. The entire working space is filled with a heating carrier 14. In order to meet the comprehensive performance of the heating carrier, the heating carrier is selected to be a high-quality carbon block.

[0027] The size of the working space of the molten salt section and the gaps between the heating carriers determine the capacity of the molten salt, which needs to be determined based on the production capacity of the device and the characteristics of the raw materials.

[0028] When the heating carrier carbon block 14 is filled, it should be in close contact with the working surface of the heating electrode 5 to ensure that the heating electrode 5 and the heating carrier 14 work properly.

[0029] The heating electrode 5 is a water-cooled metal-graphite electrode with excellent performance.

[0030] Reasonable placement of the upper portion of the heating carrier 14 is beneficial to the chlorination of unreacted oxides (charges) falling on its surface and the filtration and purification of molten salt, and is beneficial to further uniform distribution of the chlorine gas flow, and also has the function of a chlorine pre-distributor.

[0031] The heating electrode 5 is arranged at the lower part of the molten salt section, which is conducive to the molten salt becoming an effective conductor and at the same time the molten salt effectively protects the electrode.

[0032] Several groups of cooling water inlet pipes 2 and corresponding cooling water outlet pipes 8 are provided in the furnace to ensure the temperature drop requirement of the air flow in the furnace.

[0033] The expansion section refractory lining 11, the boiling section refractory lining 12 and the molten salt section refractory lining 13 ensure the long-term working performance of the boiling chlorination furnace in high temperature and corrosive medium environments.

[0034] The chlorine distributor 4 is arranged on the upper surface of the heating carrier of the molten salt section or slightly below it, depending on the need for uniform distribution of the chlorine gas flow.

[0035] The fault slag discharge port 9 is used for slag discharge when the unreacted oxide solid residue layer accumulated on the heating carrier 14 thickens to a certain extent during the normal production cycle of the boiling chlorination furnace and the furnace pressure difference increases to exceed the normal range.

[0036] To sum up, the inventive device, through the precise combination of the furnace cover slurry spray port 1, the cooling water inlet pipe 2, the feed port 3, the chlorine distributor 4, the heating electrode 5, the titanium tetrachloride nozzle 6, the furnace gas outlet pipe 7, the cooling water outlet pipe 8, the fault slag discharge port 9, the molten salt discharge port 10, the expansion section refractory lining 11, the boiling section refractory lining 12, the molten salt section refractory lining 13 and the heating carrier 14, forms a new process and device with complete functions suitable for preparing titanium tetrachloride from high calcium, magnesium and high titanium slag. The invention solves the problem of the availability of high-calcium-magnesium-high-titanium slag raw materials; enables high-boiling-point chlorides to smoothly enter the molten salt section from the boiling section in a molten state, avoids the adverse effects on the continuous and stable production caused by the retention and accumulation of high-boiling-point chlorides in the lower part of the boiling section, and realizes the continuous and stable operation of the production of titanium tetrachloride by boiling chlorination of high-calcium-magnesium-high-titanium slag; strengthens the thermodynamic and kinetic conditions for the chlorination reaction of unreacted furnace charges falling to the bottom of the boiling bed (the upper surface of the heating carrier), which is conducive to improving the utilization rate of raw materials; improves the quality of high-boiling-point chloride salts to make them useful materials; and is a new process and device for preparing titanium tetrachloride by boiling chlorination suitable for the characteristics of my country's titanium resources.

[0037] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An apparatus for preparing titanium tetrachloride from high-calcium-magnesium-high-titanium slag, comprising a cylindrical fluidized bed, comprising a fluidized section (b) for the primary reaction of the high-calcium-magnesium-high-titanium slag, petroleum coke, and chlorine; a transition section (c) for mitigating the rising velocity of the furnace gas; an expansion section (d) for dilute-phase chlorination during the free settling of dust in the furnace gas; and a molten salt section (a) for accumulating and maintaining the heat of high-boiling-point chlorides in the liquid phase. The apparatus is characterized in that: The top heating carrier interface of the bottom molten salt section (a) directly connects to the boiling section (b) above it; from the top of the boiling section (b) through a 60° cone angle to the transition section (c) above it; from the top of the transition section (c) directly connects to the expansion section above it; from the expansion section (d) into the furnace top to the furnace gas outlet at the furnace top; The bottom of the molten salt section (a) is provided with a molten salt discharge port (10), a chlorine distributor (4) is arranged on the upper surface or slightly below, a heating electrode (5) is provided at the lower part, and the entire space of the molten salt section (a) is filled with a heating carrier (14) with gaps left, and the heating carrier (14) is a carbon block.

2. The device for preparing titanium tetrachloride from high calcium, magnesium and titanium slag according to claim 1, characterized in that: The upper part of the boiling section (b), the middle part of the expansion section (d) and the lower part of the furnace top are required to be provided with a plurality of groups of cooling water inlet pipes (2) and corresponding cooling water outlet pipes (8) according to the temperature drop requirements; the furnace top is also provided with a slurry spraying port (1), a titanium tetrachloride nozzle (6) and a furnace gas outlet pipe (7); the middle and lower part of the boiling section (b) is provided with a feeding port (3); the molten salt section (a) is provided with a fault slag discharge port (9) located at the upper part of the heating carrier (14).

3. The device for preparing titanium tetrachloride from high calcium, magnesium and titanium slag according to claim 1, characterized in that: A total of three heating electrodes are provided on the same circumferential plane of the heating electrode (5), with an angle of 120° between them.

4. The device for preparing titanium tetrachloride from high calcium, magnesium and titanium slag according to claim 1, characterized in that: The chlorine distributor (4) is located on the upper part of the heating carrier (14), and the molten salt discharge port (10) is located at the bottom of the molten salt section.

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