TiCl₄

Titanium Tetrachloride（TiCl₄）

1.Raw Material Routes
The main raw materials for titanium tetrachloride production include natural rutile, synthetic rutile, and high-titanium slag.
Among these, natural rutile (TiO₂ 90%–97%) has the highest TiO₂ grade, but is scarce in resources and expensive. It is mainly used for the production of high-end chloride-process titanium dioxide, titanium sponge, and semiconductor-grade titanium tetrachloride. Domestic production is extremely low, and it relies heavily on imports from Australia and Sierra Leone.Synthetic rutile (TiO₂ 90%–95%) is processed from ilmenite. Its quality is close to that of natural rutile, with a cost higher than high-titanium slag but lower than natural rutile. It is suitable for chloride processes that require higher-grade feedstocks. High-titanium slag (TiO₂ 70%–95%) is the dominant raw material for titanium tetrachloride production in China, accounting for over 90% of the domestic production capacity. It offers moderate cost, stable supply, and mature process technology, making it well-suited for fluidized-bed chlorination. The main domestic production areas for high-titanium slag are Panxi in Sichuan, Yunnan, and Inner Mongolia. With sufficient domestic supply and stable prices, it offers the best compatibility with the fluidized-bed chlorination process and significantly lower costs compared to rutile-based feedstocks. It can also be further purified to produce high-purity titanium tetrachloride, balancing cost efficiency with product grade flexibility.

2.Process Technology Scheme
2.1 Chlorination Process Technology Scheme
There are two industrial processes for the production of TiCl₄ fluidized-bed chlorination and molten-salt chlorination.Fluidized-bed chlorination features large single-unit capacity, advanced technology, high chlorination efficiency (≥95%), and simple, stable operation. Apart from the former Soviet Union, which adopted a distinct molten-salt chlorination process for titanium tetrachloride production, nearly all other producers worldwide employ the fluidized-bed chlorination process. It represents the mainstream and development trend for industrial TiCl₄ production. However, the fluidized-bed chlorination process imposes relatively stringent requirements on feedstock particle size and composition, with particularly strict limits on calcium and magnesium content (MgO1.0%, CaO0.5%). In contrast, the molten-salt chlorination process has more lenient feedstock requirements and can tolerate higher calcium and magnesium levels. Nevertheless, the scale-up of molten-salt chlorination furnaces is difficult, making equipment large-scaleization challenging. In addition, there is no satisfactory treatment method for the spent salt and residue generated, posing environmental concerns.Therefore, under current technological conditions, the construction of large-scale chlorination plants should adopt the internationally accepted fluidized-bed chlorination process.
2.2 Selection of Purification Process Technology
Crude titanium tetrachloride typically contains harmful elements such as oxygen, nitrogen, carbon, iron, and silicon, which increase the hardness of titanium sponge and must be removed.
The purification process consists of three stages: distillation - rectification - hemical treatment. The distillation stage removes high-boiling-point impurities, the rectification stage removes low-boiling-point impurities, and the chemical treatment removes vanadium.
There are four primary methods for vanadium removal from titanium tetrachloride worldwide: copper wire, aluminum powder, H₂S, and organic compounds. The comparison of these methods is presented in the table below.

Comparison of Four Industrial Vanadium Removal Methods

Organic mineral oil-based vanadium removal is currently a relatively advanced and commonly used vanadium removal process. Due to its low cost, non-toxicity, abundant availability, and low specific consumption, mineral oil can simultaneously remove chromium, iron, aluminum, and other metals and impurities during vanadium removal, while enabling continuous production of purified titanium tetrachloride. It is therefore favored by most producers.

3.Process Description
(1) Raw Material Preparation Section
High-titanium slag from the raw material warehouse is conveyed by pneumatic conveying pump to the high-titanium slag feed hopper located in front of the furnace. The particle size of the high-titanium slag is provided by the supplier in accordance with the required specifications. Petroleum coke from the warehouse is first crushed by an impact crusher and then finely ground by a high-pressure suspension roller mill. Petroleum coke with qualified particle size is then conveyed by pneumatic conveying pump to the petroleum coke feed hopper in front of the furnace for use in the fluidized-bed chlorination furnace.
(2) Chlorination Section
The high-titanium slag and petroleum coke in the front-of-furnace feed hoppers are metered by screw electronic scales, and then fed in a specified ratio and at a controlled flow rate by screw conveyors into the front-of-furnace mixed material hopper. The mixed material is then discharged through a rotary valve and a screw feeder, and is introduced into the chlorination furnace from the middle section under the assistance of nitrogen carrier gas.
The buffer tank in front of the chlorination furnace is respectively fed with compressed air, chlorine gas and (nitrogen), each controlled by a shut-off valve. Under normal operating conditions, only chlorine gas is introduced. The gases are distributed through a distributor to the respective nozzles at the bottom of the chlorination furnace, fluidizing the mixed material in the furnace. The chlorination reaction takes place at 950–1050°C. Products with relatively low boiling points are discharged from the furnace in gaseous form, while a small amount of fine particles is carried into the expansion section, where they settle back into the fluidized bed for further reaction. High-boiling-point substances and unreacted solid materials remain in the fluidized bed and are periodically discharged from the furnace through the slag outlet.
The mixed gas exiting from the top of the chlorination furnace at approximately 950°C comes into contact with sprayed TiCl4 and purified vanadium-containing slurry. The TiCl₄ in the slurry evaporates, lowering the gas temperature to 200–250°C. The solid components in the slurry serve as seed crystals, promoting the crystallization of gaseous substances such as FeCl₃, FeCl₂, and AlCl₃ onto them. These solids settle at the bottom of the dust collector and are discharged into the dust collection slurry tank, where they are continuously slurried by the dust collection circulation pump. The gas then enters a wet dust collector for further dust removal and purification before being sent to the TiCl₄ condensation system. The slurry from the wet dust collector is returned for atomization temperature control, allowing recovery of TiCl₄ and additional dust removal.
The condensation system consists of three stages of spray equipment connected in series. First, the gaseous TiCl₄ is condensed using a circulating crude TiCl₄ cooling stream that exchanges heat with cooling water, and then further condensed by a circulating TiCl₄ stream cooled with chilled brine, minimizing the TiCl₄ content in the gas. The condensed crude TiCl₄ is sent to the crude TiCl₄ storage tank or directly to the purification system.
After TiCl₄ mist droplets are recovered by a mist eliminator, the non-condensable gas enters the tail gas treatment section, where it is scrubbed with dilute hydrochloric acid and water in two stages of tail gas absorption towers to absorb HCl. The treated gas meeting emission standards is then discharged to atmosphere through a stack by a fan. The scrubbing liquid is gradually returned from the later stage to the front stage. When the hydrochloric acid concentration reaches 28%, it is discharged to the hydrochloric acid storage tank for sale. The dilute hydrochloric acid scrubbing liquid is cooled by a graphite cooler. A third-stage caustic scrubbing system is employed during start-up, shutdown, or abnormal operating conditions.
The dust collection slurry is pumped from the slurry storage tank by the filter press slurry pump to the filter press for filtration. The filtrate is sent to the FeCl₃ storage tank for sale. The filter cake is washed with industrial water to a pH of 4–5, then blown dry with compressed air, neutralized with lime, and sent to the disposal yard. The washing water is sent to the wastewater tank for return to the slurrying process.
(3) Purification Section
Crude TiCl₄ from the crude TiCl₄ storage tank or intermediate tank is fed through the overhead tank at a controlled flow rate into the reboiler. It is heated by forced external circulation, with a specified proportion of mineral oil added. Under controlled temperature and pressure, the VOCl₃ in the crude TiCl₄ reacts to form higher-boiling-point VOCl₂, which remains in the liquid phase, while TiCl₄ is vaporized. When the solid-to-liquid ratio in the material reaches a certain value, a portion is discharged to the slurry tank and returned to the chlorination dust collection atomization system for TiCl₄ recovery, while high-boiling-point impurities are sent to the dust collection residue. The TiCl₄ vapor passes through a packed tower for separation of high-boiling-point impurities. The TiCl₄ gas exiting the top of the tower is condensed; part is returned as reflux, and the remainder is sent to a float valve tower for rectification.
Part of the TiCl₄ enters the rectification float valve tower from the middle section, coming into countercurrent contact with TiCl₄ vapor rising from the tower bottom, which contains impurities such as SiCl₄. On each tray, mass transfer occurs between the gas and liquid phases under countercurrent flow. Due to the decreasing temperature gradient, less volatile TiCl₄ is gradually cooled into the liquid phase and flows downward. Upon reaching a specified purity, it is discharged from the tower bottom to the intermediate inspection tank. After sampling and quality verification, it is sent to the finished product tank for sale. The more volatile SiCl₄ and non-condensable impurity gases continue to rise and exit from the top of the tower, entering the condenser and being collected in the intermediate tank. A portion is returned as reflux for temperature control of the float valve tower, while the remainder is sent to the SiCl₄ storage tank. Non-condensable gases are sent to the off-gas treatment section. Mixtures containing certain proportions of TiCl₄ and SiCl₄ may be sent to another rectification float valve tower for further separation, allowing additional TiCl₄ recovery and production of high-purity refined SiCl₄ for sale.
The vanadium residue slurry entering the slurry system is returned to the chlorination system for temperature control and TiCl₄ recovery.

4.Process flow diagram (PFD)

Schematic diagram of chlorination process

Schematic diagram of purification process
 

5. Consumption Quotas
Using high-titanium slag as raw material, the consumption quotas per ton of product are shown in Table1.

Table1 Consumption Quotas per Ton of Titanium Tetrachloride Product

6. Main Process Equipment
(1) Chlorination Furnace
The fluidized-bed chlorination furnace is a vertical cylindrical vessel with a flat bottom and a spherical crown top head. The shell is made of carbon steel, lined with special refractory bricks. The furnace body has three slag outlets, located at the bottom and the upper side. Each slag outlet serves a different function: the upper side outlet is used for periodic slag discharge during normal operation, while the bottom outlet is used during furnace shutdown for slag removal. The lower section of the furnace is equipped with a bottom plate, which is fitted with several chlorine gas nozzles made of INCONEL 600 material.
Titanium-rich feed material and petroleum coke are introduced from the middle section of the furnace, while chlorine gas is fed from the bottom. The operating temperature inside the furnace is maintained at 950–1050°C.
(2) Solid-Phase Dust Removal Equipment
Dust removal is carried out by two gravity settlers connected in series with partition plates. The settlers consist of two independent cylindrical chambers, with their bottoms interconnected by a dust hopper. The mixed gas enters from the upper side of the first chamber, flows downward through the chamber, passes through the dust hopper, then rises through the second chamber and exits from the upper side to the next stage of equipment. The internal surface of the first-stage settler is lined with refractory concrete, and a rotary atomizer is installed at the top for spraying slurry. Two dust discharge ports are located at the bottom center of the dust hopper, each connected to a slag pot by valves.
(3) Liquid-Phase Dust Collection Equipment
The liquid-phase dust collection equipment consists of a tower body, slurry circulation pumps, agitators, a circulation pump tank, and a shell-and-tube heat exchanger. The tower body is composed of two cylindrical chambers with their bottoms interconnected. Each chamber is equipped with slurry spray nozzles at the top. The mixed gas enters from the upper side of the first chamber, flows downward through the chamber, passes through the bottom into the second chamber, rises upward, and exits from the upper side to the next stage of equipment. During this process, the mixed gas comes into contact with liquid TiCl₄, which is cooled by the heat exchanger and sprayed downward. The solid particles that escaped from the solid dust collector are further captured. The slurry then enters the circulation pump tank and is sent to the top of the chlorination furnace for temperature control and TiCl₄ recovery.
(4) Condensation Equipment
The three-stage condensation system consists of refrigeration units, scrubber towers, shell-and-tube heat exchangers, and circulation pump tanks. Each stage of the spray tower is composed of two cylindrical chambers with their bottoms interconnected. The furnace gas enters from the upper section of the first chamber, flows downward, then passes through the bottom into the second chamber, flows upward, and exits from the top to the next condensation stage. Several nozzles are installed inside the tower. The condensate, which is cooled TiCl₄ liquid, is sprayed from the top of the tower and flows downward, coming into co-current and countercurrent contact with the furnace gas. The TiCl₄ in the furnace gas condenses into liquid and, together with some impurities, enters the circulation pump tank. After being cooled by heat exchangers, it is recycled to condense the mixed gas. The TiCl₄ in the circulation pump tank continuously overflows to the intermediate storage tank.
(5) Tail Gas Absorption Equipment
Tail gas absorption consists of four stages of scrubbing absorption towers. Each stage is composed of two FRP towers and a circulation pump tank. The scrubbing liquid, using clean water, is sprayed from the top of the tower, flowing downward in co-current and countercurrent contact with the furnace gas. Hydrogen chloride and other impurities in the furnace gas condense into liquid, flow into the circulation pump tank, and are then sent to the storage tank.
The last stage serves as a safeguard measure, using 20% caustic soda solution as the scrubbing liquid. It is activated when the unit is operating abnormally or when tail gas concentrations exceed the permissible limits. The sodium hypochlorite generated is sent to the storage tank.
(6) Vanadium Removal Distillation Equipment
The vanadium removal distillation equipment consists of tube-and-tube heat exchangers, reactors, circulation pumps, a packed tower, condensers, a reflux drum, and an oil feeding system.
Heating is provided by two tube-and-tube heat exchangers connected in series. The surface of the reactor vessel is insulated with a layer of asbestos and Portland cement for thermal insulation.
(7) Silicon Removal Rectification Equipment
The silicon removal rectification equipment consists of a float valve tower, a distillation kettle, a double-tube condensers, and an inspection tank. The float valve tower comprises 40 trays, with a tower height of approximately 12,320 mm. The distillation kettle is heated by a steam-heated internal tube heat exchanger. The purification equipment also includes float valve towers, electrically heated distillation kettles, and double-tube heat exchangers.