A method of producing reduced ilmenite
By using a pot furnace for self-heating and waste heat recovery, the problems of high cost and incomplete reduction in the production of ilmenite have been solved, achieving low-cost and high-efficiency reduction and producing high-quality reduced ilmenite that meets national standards.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG YUXIAO ZIRCONIUMTITANIUM MINING CO LTD
- Filing Date
- 2026-03-30
- Publication Date
- 2026-06-02
AI Technical Summary
The existing process for reducing ilmenite consumes a lot of heat, resulting in high production costs, and traditional processes suffer from incomplete reduction.
The reduction of carbon-containing pellets is carried out using a pot furnace. The high-temperature reduction is maintained by a combustible gas self-heating flue, combined with the recovery of waste heat by a steam generator. The carbothermic reduction reaction is achieved by intermittent feeding and micro-positive pressure control of the reduction atmosphere.
It reduces the production cost of reduced ilmenite, improves reduction efficiency, and produces products of higher quality than those made using traditional processes, meeting national standards.
Smart Images
Figure CN122128545A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ironmaking technology, and more particularly to a method for producing reduced ilmenite. Background Technology
[0002] Reduced ilmenite is a dark gray mineral powder. Because its main component is TiO2, it plays a stabilizing role in the arc, thus improving the processing performance of welding electrodes. Simultaneously, reduced ilmenite contains nearly 30% elemental iron, which can significantly improve the deposition efficiency of welding materials. Therefore, reduced ilmenite is widely used in the field of welding materials.
[0003] For the production cost of reduced ilmenite, besides the titanium ore itself, the most significant factor is the heat consumed during the reduction process. For example: Total mass of materials: 1000 kg titanium concentrate + 250 kg anthracite = 1250 kg - Specific heat capacity of titanium concentrate: 0.8 kJ / (kg·℃) - Anthracite specific heat capacity: 0.85 kJ / (kg·℃) - Mixed average specific heat capacity: ≈0.81 kJ / (kg·℃) - Temperature rise: 25℃ → 1190℃, ΔT = 1165℃ - Insulation: 3 hours - 1 kWh = 3600 kJ Total power consumption: 1000 kWh Statistics show that the heat energy required to maintain the reduction reaction is approximately RMB 500-700. Most factories still use coal or natural gas as their main heat source and employ rotary kilns or tunnel kilns to produce reduced ilmenite, which results in the high price per ton of reduced titanium. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides a method for producing reduced ilmenite. The method utilizes the heat of a pot furnace to reduce carbon-containing ilmenite pellets, while the combustible gases generated from the pellets continue to heat the combustion chamber, thus sustaining the reduction process without the need for external heat.
[0005] The technical solution of this invention is: A method for producing reduced ilmenite includes the following steps: 1) When carbon-containing pellets are intermittently added to the feed inlet of the pot furnace via a feeder, calcined coke particles are added after each batch of pellets is fed, and the top door of the feed inlet is closed; the addition of calcined coke particles increases air permeability and prevents the pellets from agglomerating. 2) As the carbon-containing pellets continue to drop due to material discharge through the lower discharge port, add the second batch of titanium ore carbon-containing pellets, followed by calcined coke particles. Close the top gate of the feed port and continue this feeding cycle. 3) Titanium ore carbon-containing pellets and calcined coke particles enter the preheating section, the medium-temperature section, and the high-temperature section, respectively. In the high-temperature section at a temperature of 1150-1300℃, the titanium concentrate in the titanium ore carbon-containing pellets reacts with the carbon therein, reducing the ferrous oxide therein to elemental iron, while titanium dioxide does not participate in the reaction. 4) In the medium and high temperature ranges, the titanium ore carbon-containing pellets contain volatiles and emit combustible gases. The combustible gases enter the fire channel through the side holes of the furnace and are ignited. The temperature of the fire channel is adjusted according to the air supply of the fire channel air fan. 5) The bottom of the pot furnace is the cooling zone of the entire furnace, which is connected to a steam generator. The red-hot pellets calcined in the high-temperature section are cooled in this zone, and the heat during cooling is carried away by the steam generator and converted into steam. 6) After passing through the cooling zone, it is discharged by the lower star-shaped feeder to the vibrating conveyor and sent to the next crushing and magnetic separation process, thus producing reduced titanium products.
[0006] Furthermore, The star-shaped feeder is an intermittent feeder. While feeding, it maintains a slight positive pressure of ≈0.3MPa or higher inside the furnace to maintain the reducing atmosphere inside the furnace.
[0007] Furthermore, The main equation for reduction is: FeO + C = Fe + CO, or it can be expressed as titanium concentrate participating in a carbothermic reduction reaction, with the equation: TiFeO3 + C = CO + TiO2 + Fe; at this time, the elemental iron obtained from the reaction adheres to the surface of the titanium concentrate particles.
[0008] Furthermore, The pot furnace can be heated by adding 3 pots of raw petroleum coke and 1 pot of ore pellets, or by adding ore pellets to all pots, and the temperature can be kept within the range of 1050-1200℃.
[0009] Furthermore, The formula for carbon-containing pellets is as follows: S1, 70-82 parts of titanium concentrate, of which titanium dioxide grade is greater than 50%, mesh size range 60-160 mesh, total iron 26-33%, phosphorus and sulfur ≤0.03%; S2, 12-20 parts of low-sulfur anthracite powder, with fixed carbon greater than 85%, sulfur less than 1%, and mesh size below 180 mesh; S3, 1-2 parts of desulfurizing agent, including one or more of calcium hydroxide, sodium carbonate, and sodium bicarbonate; S4, 5-8 parts of binder, of which 95% is water, 5% is pregelatinized starch or other binder.
[0010] The above ingredients are mixed in a forced mixer for 10 minutes and then pressed into balls by a 12-15MPa briquetting machine. The ball diameter is ≥20mm and ≥50mm. Then, they are dried at 200℃ to reduce the moisture content to 1-1.5%, with a compressive strength ≥1500N / ball and a drop height ≥2 times / 0.5 meters. After that, they are fed into the tank furnace.
[0011] After the reduction process is completed, the pellets are cooled, crushed, magnetically separated, impacted, and air-separated to obtain reduced ilmenite.
[0012] Reduced ilmenite can be further processed by acid washing or etching to obtain titanium-rich materials, and then roasted to obtain synthetic rutile.
[0013] The beneficial effects of this invention are 1. Utilize the low-cost self-heating mechanism of a pot furnace for producing calcined coke to produce reduced ilmenite or reduced iron or other carbothermally reduced metal oxides.
[0014] 2. The pelletizing formula and method are significantly different from those of traditional rotary kilns used for producing reduced ilmenite. When the temperature exceeds 1200℃, ring sintering occurs, but pellets do not. Moreover, they are more conducive to operation inside the pot furnace, increasing permeability and enhancing the reduction effect. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the workflow of the present invention; Figure 2 This is a diagram illustrating other feeding methods. Detailed Implementation
[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0017] The working principle of a petroleum coke canister calciner is to heat raw petroleum coke under air-isolated conditions to produce a large amount of combustible gas. This gas is adsorbed into the adjacent fire channel through negative pressure, and the heat generated after the combustible gas is ignited with appropriate air is used to supply the canister in the calciner, maintaining it at a temperature between 1150-1300℃. Finally, the raw petroleum coke is calcined at high temperature to remove volatile matter, moisture, and sulfur, resulting in calcined coke, which has a wide range of applications in the carbon industry.
[0018] 1. The furnace temperature is maintained at the high-temperature range of 1150-1300℃, which is also the normal reduction temperature for reducing ilmenite.
[0019] 2. The production of calcined coke must be carried out in a reducing atmosphere.
[0020] 3. Keep it for at least 3 hours.
[0021] 4. The reaction must be continuous and have a constant supply of heat.
[0022] All four conditions are necessary for the production of reduced ilmenite.
[0023] I. The detailed process flow of this invention is as follows: 1. When carbon-containing pellets are intermittently added to the feed inlet of titanium ore through a feeder, 30 kg of calcined coke particles are added after each batch of 200 kg pellets is fed, and the top gate of the feed inlet is closed. The addition of calcined coke particles can increase air permeability and prevent the pellets from agglomerating.
[0024] 2. As the carbon-containing pellets continue to drop due to material discharge through the discharge port below, add a second batch of 200 kg pellets, followed by 30 kg of calcined coke particles. Close the top gate of the feeding port and continue feeding in this cycle.
[0025] 3. The pellets and calcined coke particles enter the preheating section, the medium-temperature section, and the high-temperature section, respectively. Especially in the high-temperature section at 1150-1300℃, the titanium concentrate in the pellets reacts with the carbon in it, reducing the ferrous oxide in it to elemental iron, while titanium dioxide does not participate in the reaction.
[0026] 4. In the medium and high temperature sections, the carbon-containing pellets emit a large amount of combustible gas due to their volatile components. The gas enters the fire channel through the furnace side holes and is ignited. The temperature of the fire channel is adjusted according to the air supply of the fire channel fan.
[0027] 5. The bottom of the pot furnace is the cooling zone of the entire furnace, which is connected to a steam generator. The red-hot pellets after high-temperature calcination are cooled in this zone, and the heat during cooling is carried away by the steam generator and converted into steam (selling the steam can generate additional profits).
[0028] 6. After passing through the cooling zone, the material is discharged via the lower star-shaped feeder to the vibrating conveyor and sent to the next crushing and magnetic separation process, thus producing reduced titanium products. The star-shaped feeder is an intermittent discharge method, which can maintain a slight positive pressure of ≈0.3MPa or above inside the furnace while discharging material, thus effectively maintaining the reducing atmosphere inside the furnace.
[0029] 7. Its main equation is as follows: FeO + C = Fe + CO. Alternatively, it can be described as titanium concentrate participating in a carbothermic reduction reaction. The equation is: TiFeO3 + C = CO + TiO2 + Fe At this point, the elemental iron obtained from the reaction adheres to the surface of the titanium concentrate particles.
[0030] 8. At this time, the pot furnace can be heated in the manner of 3 pots of raw petroleum coke and 1 pot of pellets, or in the manner of adding pellets to all pots. This scheme depends on the precise control of the furnace temperature. As long as the temperature can be kept within the range of 1050-1200℃, it will not affect the product quality if the temperature exceeds this range. This is obviously different from the traditional process of rotary kiln production of reduced ilmenite.
[0031] 9. Using a pot furnace to produce reduced ilmenite is the lowest-cost and most thorough method of reducing ilmenite to date.
[0032] II. Pellet Formulation: S1. Titanium concentrate 70-82%wt (Titanium dioxide grade greater than 50%, mesh size 60-160, total iron 26-33%, phosphorus and sulfur ≤0.03%) S2. Low-sulfur anthracite pulverized coal 12-20%wt (fixed carbon greater than 85%, sulfur less than 1%, mesh size below 180 mesh) S3. Desulfurizing agent 1-2%wt (one or more of calcium hydroxide, sodium carbonate, sodium bicarbonate, etc.) S4 binder 5-8%wt (water 95%wt, pregelatinized starch 5%wt or other binders) The total composition is 100% wt.
[0033] The above ingredients are mixed in a forced mixer for 10 minutes and then pressed into balls using a 12-15MPa briquetting machine, with a ball diameter of ≥20mm and a particle size of ≥50mm. The balls are then dried at 200℃ to reduce the moisture content to 1-1.5%, achieving a compressive strength of ≥1500N / ball and a drop resistance of ≥2 times / 0.5 meters. They are then fed into a tank furnace.
[0034] After the reduction process is completed, the pellets are cooled, crushed, magnetically separated, impacted, and air-separated to obtain reduced ilmenite.
[0035] Reduced ilmenite can be further processed by acid washing or etching to obtain titanium-rich materials, and then roasted to obtain synthetic rutile.
[0036] III. Experimental Data: After the pellets are reduced in a pot furnace, their reduction state is determined, primarily based on the ferrous oxide content. First batch: Eight samples were taken from the pellets produced each day. After cooling, crushing, impact, air separation, and magnetic separation, 100-gram samples were selected for testing. The ferrous oxide content was analyzed in the following order: 2.74% 3.32% 1.92% 3.45% 4.01% 1.99% 2.43% 4.11% Second batch: Eight samples were taken from each day's pellet production. After cooling, crushing, impact, air separation, and magnetic separation, 100-gram samples were selected for testing. The ferrous oxide content was analyzed as follows: 3.24% 3.12% 2.22% 3.03% 3.31% 2.59% 3.54% 2.19% The national standard for reduced ilmenite stipulates that the ferrous content in reduced ilmenite shall not exceed 7%, indicating that its reduction process is significantly superior to that of traditional methods.
[0037] Experimental results on pellet diameter A. Pellet diameter 10mm. Eight samples were taken from pellets produced in a single day. After cooling, crushing, impact, air separation, and magnetic separation, 100g samples were selected for analysis. The ferrous oxide content results are as follows: 6.89% 7.28% 6.98% 7.88% 8.23% 9.01% 6.92% 5.43% A. Pellet diameter 30mm. Eight samples were taken from pellets produced in a single day. After cooling, crushing, impact, air separation, and magnetic separation, 100g samples were selected for analysis. The ferrous oxide content results are as follows: 2.67% 3.56% 2.26% 3.88% 3.30% 2.42% 3.67% 3.45% This experiment clearly shows that if the particle size is too small, it will cause poor air permeability, uneven heat conduction and insufficient reducibility. Therefore, changing the particle size of the pellets can effectively solve these problems. However, the particle size should not be too large, otherwise it will affect the feeding of the feeder. Moreover, if the particle size is too large, it will lead to insufficient internal reduction.
[0038] Influence of pellet formulation one, S1, titanium concentrate 100 (titanium dioxide grade greater than 50%, total iron 26-33%, phosphorus and sulfur both ≤0.03%) S2, low-sulfur anthracite pulverized coal 25 (fixed carbon greater than 85%, sulfur less than 1%, mesh size below 180 mesh) S3, desulfurizing agent 2 (one or more of calcium hydroxide, sodium carbonate, sodium bicarbonate, etc.) S4, binder 10 (water 100, pregelatinized starch 4 or other binder) Laboratory results: TiO2 59.2%, FeO 3.56%, P 0.028%, S 0.031%, C 0.12% It fully complies with national standards, and its FeO content is significantly lower than the national standard, making it a high-quality reduced ilmenite.
[0039] two, S1. Titanium concentrate 100 (Titanium dioxide grade greater than 50%, total iron 26-33%, phosphorus and sulfur both ≤0.03%) S2. Low-sulfur anthracite pulverized coal 7 (fixed carbon greater than 85%, sulfur less than 1%, mesh size below 180 mesh) S3. Desulfurizing agent 2 (one or more of calcium hydroxide, sodium carbonate, sodium bicarbonate, etc.) S4. Binder 10 (water 100, pregelatinized starch 4 or other binder) Laboratory results: TiO2 55.8%, FeO 9.32%, P 0.029%, S 0.033%, C 0.18% It does not meet national standards, and its FeO content is significantly higher than the national standard, making it an unqualified reduced ilmenite.
[0040] This experiment shows that when anthracite is used as a reducing agent, insufficient amount of it will directly lead to a poor reduction effect.
[0041] The above description is merely a preferred embodiment of the present invention and is used only to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.
Claims
1. A method for producing reduced ilmenite, characterized in that, The work includes the following steps: 1) When carbon-containing pellets are intermittently added to the feed inlet of the pot furnace via a feeder, calcined coke particles are added after each batch of pellets is fed, and the top door of the feed inlet is closed; the addition of calcined coke particles increases air permeability and prevents the pellets from agglomerating. 2) When the titanium ore carbon-containing pellets continue to drop as the material is discharged through the discharge port below, add the second batch of titanium ore carbon-containing pellets, followed by calcined coke particles, and close the top gate of the feed port. This feeding cycle continues. 3) Titanium ore carbon-containing pellets and calcined coke particles enter the preheating section, the medium-temperature section, and the high-temperature section, respectively. In the high-temperature section at a temperature of 1150-1300℃, the titanium concentrate in the titanium ore carbon-containing pellets reacts with the carbon therein, reducing the ferrous oxide therein to elemental iron, while titanium dioxide does not participate in the reaction. 4) In the medium and high temperature ranges, the titanium ore carbon-containing pellets contain volatiles and emit combustible gases. The combustible gases enter the fire channel through the side holes of the furnace and are ignited. The temperature of the fire channel is adjusted according to the air supply of the fire channel air fan. 5) The bottom of the pot furnace is the cooling area of the entire furnace, which is connected to the steam generator. That is, the red-hot pellets after high-temperature calcination are cooled in this area, and the heat during cooling is carried away by the steam generator and converted into steam. 6) After passing through the cooling zone, it is discharged by the lower star-shaped feeder to the vibrating conveyor and sent to the next crushing and magnetic separation process, thus producing reduced titanium products.
2. The method according to claim 1, characterized in that, The star-shaped feeder is an intermittent feeder. While feeding, it maintains a slight positive pressure of ≈0.3MPa or higher inside the furnace to maintain the reducing atmosphere inside the furnace.
3. The method according to claim 1, characterized in that, The main equation for reduction is: FeO + C = Fe + CO, or it can be expressed as titanium concentrate participating in a carbothermic reduction reaction, with the equation: TiFeO3 + C = CO + TiO2 + Fe; at this time, the elemental iron obtained from the reaction adheres to the surface of the titanium concentrate particles.
4. The method according to claim 1, characterized in that, The pot furnace can be heated by adding three pots of raw petroleum coke and one pot of ore pellets, or by adding pellets to all pots, so that the temperature is always controlled within the range of 1050-1200℃.
5. The method according to claim 4, characterized in that, The furnace can also be fed using a method of two tanks of raw petroleum coke and one tank of pellets.
6. The method according to claim 4, characterized in that, The furnace can also be fed by one tank of raw oil and one tank of pellets.
7. The method according to claim 4, 5, or 6, characterized in that, The formula for carbon-containing pellets is as follows: S1, 70-82 parts of titanium concentrate, of which titanium dioxide grade is greater than 50%, mesh size range 60-160 mesh, total iron 26-33%, phosphorus and sulfur ≤0.03%; S2, 12-20 parts of low-sulfur anthracite powder, with fixed carbon greater than 85%, sulfur less than 1%, and mesh size below 180 mesh; S3, 1-2 parts of desulfurizing agent, including one or more of calcium hydroxide, sodium carbonate, and sodium bicarbonate; S4, 5-8 parts of binder, of which 95% is water, 5% is pregelatinized starch or other binder.
8. The method according to claim 7, characterized in that, The above ingredients are mixed in a forced mixer for 10 minutes and then pressed into balls by a 12-15MPa briquetting machine. The ball diameter is ≥20mm and ≥50mm. Then, they are dried at 200℃ to reduce the moisture content to 1-1.5%, with a compressive strength ≥1500N / ball and a drop height ≥2 times / 0.5 meters. After that, they are fed into the tank furnace.
9. The method according to claim 7 or 8, characterized in that, After the reduction process is completed, the pellets are cooled, crushed, magnetically separated, impacted, and air-separated to obtain reduced ilmenite.
10. The method according to claim 9, characterized in that, Reduced ilmenite can be further processed by acid washing or etching to obtain titanium-rich materials, and then roasted to obtain synthetic rutile.