From ore to sponge titanium – titanium metallurgy process

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From ore to sponge titanium – Titanium metallurgy process. Published on April 30, 2026, at 00:19. Xinjiang. The core stages of titanium metallurgy include ore processing and enrichment → preparation of titanium-rich materials → production of titanium tetrachloride (TiCl4) → purification of crude TiCl4 → production of sponge titanium through magnesiothermic reduction (Kroll process) → purification via vacuum distillation → and further processing of titanium through melting. The most widely used industrial method is the Kroll process (magnesium reduction), while the Hunter process (sodium reduction) is used only for the production of high-purity titanium powder on a limited scale. I. Titanium ore beneficiation The core processes of titanium metallurgy consist of seven main steps: titanium ore beneficiation and enrichment → preparation of titanium-rich materials → production of titanium tetrachloride (TiCl₄) → purification of crude TiCl₄ → production of sponge titanium via magnesium thermal reduction (Kroll process) → vacuum distillation for purification → deep processing of molten titanium. Industrially, the Kroll process (magnesium reduction method) is the dominant technique; the Hunter process (sodium reduction method) is used only for the niche production of high-purity titanium powder. I. Ilmenite processing (raw ore → titanium concentrate, with TiO₂ content of 45%~55%) 1. Raw materials: Industrial ilmenite mainly consists of ferroilmenite (FeTiO₃, accounting for over 90% of titanium resources), rutile (TiO₂, high purity), and vanadium-titanium magnetite ； China’s titanium resources are concentrated in the Panxi region of Sichuan, Yunnan, and Chengde in Hebei. The titanium reserves associated with vanadium-titanium magnetite in the Panxi region account for 90% of the country’s total, making it the core base for titanium metallurgy in China. 2. Mineral processing: Utilizing the differences in density, magnetism, electrical conductivity, and surface hydrophobicity between ilmenite and gangues (quartz, feldspar, chlorite, ilmenite pyroxene), ilmenite is separated through combined sorting methods, while harmful impurities such as SiO₂, Al₂O₃, MgO, and CaO are removed. 3. Process 1: Crushing and grinding: Rough crushing with jaw crushers → fine crushing with cone crushers → grinding in ball mills. The particle size after grinding should be such that particles smaller than -0.074 mm account for 60%~75%, to ensure the complete dissociation of ilmenite; the original rock ore needs to be ground to an even finer particle size. 2. Re-selection and pre-enrichment: Equipment includes spiral chutes (rough separation), shaking tables (fine separation), and centrifugal concentrators (recovery of fine particles) ； Utilizing the difference in density between ilmenite (4.7–4.8 g/cm³) and gangue (2.6–2.7 g/cm³), this method can discard 40%–50% of low-grade tailings. It is suitable for beach sand deposits and coarsely disseminated ores; it features low costs and no pollution, but the recovery rate is approximately 65%–75%. 3. Magnetic separation (key process): Ilmenite has weak magnetism (specific magnetic susceptibility of 250~350×10⁻⁶ cm³/g), while the gangue is non-magnetic ； A combination of weak magnetic separation (0.2~0.4T, for iron removal) and strong magnetic separation (0.8~1.4T, for titanium selection) is employed, using wet drum magnetic separators and vertical ring high-gradient magnetic separators as the equipment ； The TiO₂ grade of the concentrate obtained through strong magnetic separation can reach 47%~50%, while the impurity Fe₂O₃ level is reduced to below 8%. 4. Flotation (improvement of fine-grained concentrate quality): For -45μm fine-grained ilmenite, pretreatment with sulfuric acid for 30 minutes (pH=1.8) is carried out to remove surface Mg and Ca impurities ； Reagent system: collector oleic acid/hydroxamic acid (50–80 g/t), inhibitor water glass (1200–1500 g/t), activator Pb(NO3)2 (100–150 g/t) ； The pH is controlled at 4.5–5.5, the flotation temperature is 25–30°C; the TiO₂ content in the concentrate increases to 52%–55%, with a recovery rate of 80%–85%. 5. Electroseparation (concentrate purification of placer ores): Ilmenite has good electrical conductivity, while zircon and quartz have poor conductivity. Separation is carried out using a high-voltage electric field (20–30 kV). The equipment used is a roller-type electrostatic separator. The ore must be dried in advance until its moisture content is less than 1%. This process is used to separate ilmenite from zircon; the impurity content of the concentrate, ZrO₂, is less than 0.5%. Pangang Group Mining Company: It employs a combined process of crushing, grinding, gravity separation, magnetic separation, and flotation to process 10 million tons of vanadium-titanium magnetite per year, producing 800,000 tons of titanium concentrate (with 47% TiO2) annually; it is the largest titanium concentrate production base in China. II. Preparation of titanium-enriched materials from titanium concentrate to titanium slag/artificial rutile: TiO₂ content is ≥80% in the titanium concentrate, while it is only 45%~55%; direct chlorination requires high energy consumption and involves many impurities. Therefore, it is necessary to prepare titanium-enriched materials (titanium slag, artificial rutile), which represents a key preliminary step in the production of titanium dioxide and sponge titanium via chlorination methods. (I) Electric furnace reduction smelting method (used for producing titanium slag; the industrial mainstream method, with TiO₂ content ranging from 80% to 95%)
1. Process: Titanium concentrate (FeTiO₃) and coke (reducing agent) are heated to temperatures between 1600–1800°C. Under these conditions, iron oxides are reduced to metallic iron (which has a high density and sinks to the bottom), while titanium oxides accumulate on the upper layer, forming titanium slag. This process enables effective separation of titanium from iron. 2. Reaction equations: FeTiO₃ + C → Fe + TiO₂ + CO↑ (main reaction); 2Fe₂O₃ + 3C → 4Fe + 3CO₂↑ (reduction of impurity iron); TiO₂ + C → TiO + CO↑ (formation of a small amount of low-valent titanium). Equipment: hermetically sealed DC electric arc furnace (10,000–45,000 kVA; the most common model in China is 25,000 kVA), with the furnace body being water-cooled; graphite electrodes with a diameter of 600–800 mm ； Ratio: Titanium concentrate: coke = 100:18~22 (fixed carbon ≥90%), additive fluorite (CaF₂) 2%~3% (to reduce slag melting point) ； Temperature: Pool temperature 1650~1750°C, furnace top temperature 800~900℃ ； Cycle: It takes 6–10 hours to smelt 100 tons of charge; the outlet temperature is 1500–1550°C for titanium slag and 1450–1500°C for molten iron℃ ； Separation: Allow to stand for 30–60 minutes; the lower layer of molten iron (containing 2%–3% Ti) is recovered, while the upper layer of titanium slag is quenched in water or cooled slowly and then crushed to a particle size of 0.5–5 mm. 4. Specifications: High-titanium slag (TiO₂ ≥ 92%, designed for the chlorination process); ordinary titanium slag (TiO₂ 80%~85%, used in the sulfuric acid process for titanium dioxide production), with impurities of MgO + CaO < 5% and Fe < 5%. Yunnan Xinli Nonferrous Metals: The 25,000 kVA submergence arc furnace has an annual production capacity of 100,000 tons of high-titanium slag (with 94% TiO₂). This product is supplied to domestic titanium sponge and titanium dioxide producers utilizing the chlorination process ； Pangang Titanium’s 12,500 kVA electric arc furnace produces 80,000 tons of titanium slag per year. (II) Leaching of synthetic rutile with hydrochloric acid, TiO₂ ≥ 90% 1. Process principle: Titanium concentrate is first oxidized and roasted at 600–700°C, and then leached with 20%–25% hydrochloric acid to dissolve impurities such as iron, magnesium, and calcium; titanium oxide remains insoluble. After solid-liquid separation, synthetic rutile is obtained. 2. Core reaction equation: FeTiO₃ + 4HCl → TiCl₄ + FeCl₂ + 2H₂O (impurity leaching); TiO₂ (titanium slag) does not react with dilute hydrochloric acid (selective leaching). 3. Equipment: horizontal rotary calciner, high-pressure leaching tank (lined with rubber/titanium), plate and frame filter press ； Temperature: 650°C, time: 2–3 hours, air volume: 1.2–1.5 times the theoretical amount ； Leaching: Hydrochloric acid concentration of 22%, liquid-solid ratio of 4:1, temperature of 100–110°C, pressure of 0.2–0.3 MPa, time of 4–6 hours ； Washing: dilute hydrochloric acid → washing with water; the filtrate is used to recover hydrochloric acid (by distillation), and the filter cake is dried at 120°C. Advantages: High TiO₂ content (92%~95%) and low impurities ； Disadvantages: Hydrochloric acid is highly corrosive; equipment costs are high; energy consumption for acid recovery is significant. Only a few domestic enterprises use it. III. Titanium tetrachloride (TiCl₄): Titanium-rich materials → crude TiCl₄. TiCl₄ is a key intermediate product in the production of sponge titanium and titanium dioxide. At room temperature, it is a colorless liquid (boiling point: 136.4°C; melting point: -24°C). Industrially, fluidized-bed chlorination (the mainstream method) and fixed-bed chlorination are employed. China has developed a unique fluidized-bed chlorination furnace without sieve plates, which is well-suited for processing low-grade titanium slag from Panzhihua ores. 1. The process involves reacting titanium-rich feedstock (TiO₂), petroleum coke (reducing agent), and chlorine gas (chlorinating agent) at high temperatures of 800–1000°C to produce gaseous TiCl₄. Impurities such as Fe, Al, and Mg form FeCl₃, AlCl₃, and MgCl₂, which are discharged along with the furnace gases; upon condensation, crude TiCl₄ is obtained. 2. Reaction equations: TiO₂ + 2C + 2Cl₂ → TiCl₄↑ + 2CO↑ (main reaction, 850–950°C); TiO₂ + C + 2Cl₂ → TiCl₄↑ + CO₂↑ (side reaction, <800°C); Fe₂O₃ + 3C + 3Cl₂ → 2FeCl₃↑ + 3CO↑ (chlorination of impurities). 3. Fluidized chlorination process – the industrial standard method; it involves a fluidized chlorination furnace without sieve plates, as well as components such as a screw feeder, chlorine compressor, flue gas condenser, bag filter, and spray tower. Operation steps: 1. Raw material pretreatment: Titanium slag (particle size 0.1~1 mm) + petroleum coke (particle size 0.2~2 mm, fixed carbon ≥95%) are mixed in a ratio of 100:20~25, and then dried until the moisture content is <0.5% ； 2. Heating inside the furnace: First, nitrogen is introduced to displace the air, and the temperature is raised to 600°C; then chlorine is introduced ； 3. Chlorination reaction: The furnace temperature is controlled at 850–950°C; the amount of chlorine gas introduced is 1.1–1.2 times the theoretical amount. The fluidization velocity of the material layer in the furnace is 0.3–0.5 m/s, and the residence time is 15–25 minutes ； 4. Furnace gas treatment: Furnace gas (TiCl₄, FeCl₃, CO) → Cyclone dust removal (to remove solid particles) → Primary condensation (at 80–100°C; condenses FeCl₃ and AlCl₃) → Secondary condensation (at 20–40°C; condenses TiCl₄) → Off-gas treatment (alkaline solution absorbs Cl₂ and CO) ； 5. Slag discharge: Unreacted coke powder and MgCl₂ slag are periodically discharged from the furnace bottom, enabling continuous production. Indicators: Crude TiCl₄ composition: TiCl₄ 92%~95%, VOCl₃ 1%~3%, FeCl₃ 0.5%~1.5%, SiCl₄ 0.2%~0.8% ； The chlorination efficiency is 90%–95%, and the daily production capacity of a single furnace is 50–150 tons of crude TiCl₄. Pangang Titanium Industry: Screenless fluidized chlorination furnace (2.8m in diameter), with a daily production capacity of 120 tons of crude TiCl₄ per furnace. It is suitable for processing Pangang’s titanium slag, which has a high MgO content; this furnace effectively addresses the problem of slag formation and blockage encountered in conventional screen-type furnaces ； Zunyi Titanium Industry (a veteran domestic sponge titanium producer): It has a 3.0m chlorination furnace, with an annual output of 80,000 tons of crude TiCl₄. IV. Purification of crude titanium tetrachloride: Crude TiCl₄ → pure TiCl₄, with impurities <0.01%. Crude TiCl₄ contains impurities such as VOCl₃, FeCl₃, SiCl₄, and AlCl₃. Direct reduction would result in excessive levels of oxygen and vanadium in the resulting titanium sponge. The key step is to remove VOCl₃ (the most critical impurity), as well as FeCl₃ and SiCl₄. The predominant industrial processes are the combined copper powder vanadium removal and distillation process, as well as the aluminum powder vanadium removal process. Copper powder vanadium removal + double-column distillation process – the mainstream method in China. 1. Principle of vanadium removal: An oxidation-reduction reaction occurs between copper powder and VOCl₃, resulting in the formation of solid VCl₂ precipitate that is insoluble in TiCl₄; this enables the separation of vanadium ； FeCl₃ and SiCl₄ are separated by distillation (due to differences in boiling points). 2. Reaction equations: Cu + VOCl₃ → CuCl + VCl₂↓ (main vanadium removal reaction); 2Cu + FeCl₃ → 2CuCl + Fe↓ (side reaction for iron removal). 3. Parameters: 1. Copper powder vanadium removal tower: packed tower (diameter 1.2–1.8 m, height 15–20 m), with packing made of red copper Bauler rings (φ25 mm) ； Operating temperature: 130–135°C (boiling point of TiCl₄); atmospheric pressure. The amount of copper powder added is 1.2–1.5 times the molar amount of VOCl₃. Residence time: 2–3 hours ； 2. Crude distillation tower (for removing high-boiling substances): plate-type distillation tower, with a tower temperature of 136–140°C; TiCl₄ and SiCl₄ are obtained at the top of the tower, while FeCl₃ and VCl₂ residues are discharged from the bottom ； 3. Distillation column (for removing low-boiling substances): Packed distillation column; column temperature is 134–136°C. SiCl₄ (boiling point: 57.6°C) is discharged from the top of the column, while pure TiCl₄ (purity ≥99.99%) is obtained at the bottom. 4. Specifications: Pure TiCl₄: V＜0.005%, Fe＜0.001%, Si＜0.002%, Cl₂＜0.001%, meeting the national standards for titanium sponge production (GB/T 25954-2010). (II) The aluminum powder method for vanadium removal is highly efficient. 1. Principle: Aluminum powder reduces VOCl₃ to form VCl₃ precipitate, resulting in a higher vanadium removal efficiency; no copper slag is generated, making it more environmentally friendly. 2. Reaction equation: Al + 3VOCl₃ → AlCl₃ + 3VCl₃↓ Luoyang Shuangrui Wanji Titanium Industry: Utilizes an aluminum powder-based vanadium removal process; has a pure TiCl₄ production capacity of 150,000 tons per year. The vanadium content in the product is less than 0.003%. The product is used in the production of aerospace-grade titanium sponge. V. Magnesium thermoreduction process – Kroll process: Pure TiCl₄ is converted into spongy titanium. This is the only mainstream industrial process. Invented in 1940 by Luxembourgish scientist Wilhelm Kroll, this process is used to produce over 95% of the world’s spongy titanium. The core step involves reducing TiCl₄ with magnesium under a high-temperature inert atmosphere, resulting in the formation of spongy titanium and MgCl₂. The process consists of three stages: reduction, vacuum distillation, and crushing/sizing. 1. Principle of the reduction reaction: Under argon protection (which isolates O₂ and N₂ to prevent oxidation and nitridation of titanium), liquid magnesium reduces gaseous TiCl₄ at 800–850°C, producing porous titanium sponge (with pores containing Mg and MgCl₂). 2. Reaction equations: TiCl₄(g) + 2Mg(l) → Ti(s) + 2MgCl₂(l) ΔH = -513 kJ/mol (main reaction, 825°C); TiCl₄ + Mg → TiCl₂ + MgCl₂ (intermediate reaction); TiCl₂ + Mg → Ti + MgCl₂ (deep reduction). 3. Reduction process – integrated reduction-distillation. Equipment: a combined reduction-distillation reactor (steel reactor vessel), with a diameter of 1.8–2.4 m and a height of 6–8 m, lined with molybdenum plates and equipped with external electric heating ； Operating steps: 1. Charging and preheating: Add magnesium ingots (industrial pure magnesium ≥99.8%) to the reactor; use 20%–30% excess Mg (to ensure complete reduction of TiCl₄). Evacuate the reactor, then purge it with argon (pressure: 0.05–0.1 MPa). Heat to 650–700°C until the magnesium ingots melt ； 2. Reduction of TiCl₄ feed: Pure TiCl₄ is slowly poured in through pipes from the top of the tank, at a feed rate of 80–120 kg/h; the temperature inside the tank is maintained at 800–850°C, and a slight positive pressure of argon (0.02–0.05 MPa) is applied to prevent air from entering ； The reaction lasts for 40–60 hours, with a molar ratio of TiCl₄ to Mg of 1:2.3–2.5 ； 3. Determination of the reaction endpoint: After the addition of TiCl₄ is complete, maintain the temperature for 2–3 hours; if there are no yellow-green TiCl₄ vapors in the tank, the reduction process is complete ； 4. Direct vacuum distillation (core of the combined method): After reduction is complete, without cooling, the temperature is raised directly to 950–1050°C; the vacuum system is activated, with a vacuum level of 1–5 Pa, and the distillation process lasts 40–50 hours ； Mg (boiling point 1090°C) and MgCl₂ (boiling point 1412°C) evaporate and are condensed in the external condenser; pure sponge titanium remains inside the tank ； 5. Cooling and discharge: After distillation is complete, argon is introduced to cool the mixture to room temperature; then the tank lid is opened and the sponge titanium mass is removed. Parameters: The production capacity per tank is 5–10 tons of sponge titanium; the reduction temperature is 825°C, the distillation temperature is 1000°C, the vacuum level is 3 Pa, and the argon consumption is 0.8–1.2 m³ per ton of titanium. 4. Principle of vacuum distillation: Taking advantage of the large difference in boiling points between Mg, MgCl₂, and titanium (the boiling point of titanium is 3287°C), under high temperature and high vacuum, the impurities Mg and MgCl₂ volatilize and are separated, raising the purity of sponge titanium to 99.6%–99.9%. 5. Hunter method – a less common sodium reduction process. Invented by Hunter in 1910, it uses metallic Na as a reducing agent; the reaction temperature is 800–900°C. The reaction equation is: TiCl₄ + 4Na → Ti + 4NaCl ； Advantages: fast reaction speed, fine titanium sponge powder ； Disadvantages: High cost of Na, difficulty in recovering NaCl; it is used only for high-purity titanium powder (in aerospace applications). Zunyi Titanium Industry in China produces it in small quantities, with a production capacity of less than 10,000 tons per year. VI. Post-treatment of sponge titanium: Crushing → Classification → Finished product 1. Crushing: The sponge titanium lumps (which are low in hardness and porous) are first roughly crushed using jaw crushers, then moderately crushed with cone crushers, and finally finely crushed in ball mills to remove the surface oxide layer (the outer layer contains a high amount of titanium oxide and needs to be removed) ； 2. Classification: Classified by particle size: 0.83~12.7mm (industrial grade), 0.1~0.83mm (fine particles), ＜0.1mm (titanium powder) ； 3. Packaging: Sealed packaging under argon protection; classified according to the national standard GB/T 2524-2019 as Grade 0 (Ti≥99.9%), Grade 1 (Ti≥99.8%), Grade 2 (Ti≥99.7%), and Grade 3 (Ti≥99.6%) ； 4. Impurities: Grade 0 sponge titanium: O＜0.05%, Fe＜0.03%, Cl＜0.05%, N＜0.01%. Pangang Titanium Industry: Produces 15,000 tons of grade 0 sponge titanium per year, which is supplied to the aerospace and military industries ； Baotai Huashen Titanium Industry: The single reactor in its combined process has a production capacity of 8 tons, enabling an annual output of 20,000 tons of sponge titanium; it ranks among the top three in terms of production capacity in China. VII. Advanced processing of titanium melting – Sponge titanium → Titanium ingots → Titanium products. Sponge titanium has a porous structure and cannot be used directly; it must first be melted into titanium ingots, which are then processed into sheets, tubes, and rods. The mainstream industrial method is vacuum arc remelting (VAR), while electron beam melting (EBM) is used for high-end applications. 1. Vacuum arc remelting (VAR, the mainstream method): Sponge titanium is pressed into electrodes; within a vacuum furnace, the high temperature of the arc (3000°C) is used to melt the titanium, and a water-cooled copper crucible is used for cooling, thereby removing impurities such as oxygen, nitrogen, and chlorine to produce a dense titanium ingot. Pure titanium ingots (TA1, TA2), titanium alloy ingots (TC4, TA15), with an oxygen content of <0.08%. 2. Titanium processing enterprises: Titanium ingots are forged, rolled, extruded, and drawn to produce titanium sheets, tubes, rods, and wires, which are used in aircraft engines, chemical equipment, medical devices, and offshore engineering ； The leading domestic companies are Baotai Group, Western Materials, and Pangang Titanium Industry.