Method for eliminating influence of high-calcium and high-magnesium raw materials on production of titanium dioxide by chlorination process

Abstract

The invention discloses a method for eliminating the influence of high-calcium and high-magnesium raw materials on the production of titanium dioxide by a chlorination process, which comprises the following steps: adding a ferric iron material into the raw materials for producing titanium dioxide by boiling chlorination, and after boiling chlorination, forming a compound complex by ferric chloride, calcium chloride and magnesium chloride; by utilizing the property that the compound is volatilized into a gas phase under the chlorination operation temperature condition, the compound overflows out of a chlorination furnace along with chlorination tail gas, and the adverse effect of calcium and magnesium on the reaction in boiling chlorination is eliminated.

Description

Technical Field

[0001] The invention relates to the technical field of producing titanium dioxide by chlorination process, and more specifically, to a method for eliminating the influence of high calcium and magnesium raw materials on producing titanium dioxide by chlorination process. Background Art

[0002] Titanium dioxide is TiO 2 , is an important inorganic chemical pigment, which is widely used in coatings, plastics, papermaking, printing inks, rubber and other industries. It is famous for its excellent optical properties and chemical stability. As a key pigment and additive, titanium dioxide plays a vital role in these industry applications, especially in providing whiteness and opacity.

[0003] There are two main production processes for titanium dioxide: sulfuric acid process and chlorination process. At present, the main production process for titanium dioxide abroad is chlorination process, while the main production process in China is sulfuric acid process. Based on the advantages of chlorination process such as better product quality, less emission of three wastes, and easy expansion of equipment, it will inevitably become the development trend of the domestic titanium dioxide industry.

[0004] In the process of producing titanium dioxide by the chlorination method, titanium tetrachloride must be produced first. After grinding rutile ore or high-titanium slag, etc., it is continuously subjected to chlorination reaction with petroleum coke and chlorine at high temperature. Titanium dioxide and oxides of iron, silicon, vanadium, calcium, magnesium and other metals are converted into corresponding chlorides. The reaction gas is first separated from the unreacted solid dust and non-volatile chlorides by a cyclone separator, and then cooled, condensed and post-treated step by step to obtain relatively high-purity refined titanium tetrachloride. In the boiling chlorination reaction process of producing titanium tetrachloride, calcium oxide and magnesium oxide are substances that react with chlorine first. The calcium chloride and magnesium chloride generated after the reaction have high boiling points. For substances with low melting points, during the production process of titanium dioxide, under the operating temperature conditions of boiling chlorination, calcium and magnesium chlorides are in a molten state and easily adhere to other materials to form lumps of material, which leads to deterioration of fluidization conditions and even dead bed, affecting the smooth operation of the chlorination furnace. Once this happens, the furnace needs to be stopped, cooled, and the materials taken out before restarting the furnace for production. Therefore, in industry, it is generally necessary to control the raw materials used in the chlorination furnace, generally requiring the CaO content to be less than 0.12%, and the CaO+MgO to be less than 1.5%. Therefore, in industry, titanium-rich materials that meet the standards are generally used for boiling chlorination to produce titanium dioxide. The use of high calcium and magnesium materials in boiling chlorination furnaces has not yet been industrialized.

[0005] However, the market and price of titanium-rich materials with low calcium and magnesium content are basically monopolized by a few foreign oligarchs, resulting in high prices and procurement difficulties, which has caused the production cost of titanium dioxide by the chloride process to rise. It is urgent to develop a new titanium dioxide chloride production process to reduce production costs. Summary of the invention

[0006] In view of the above, the present invention provides a method for eliminating the influence of high calcium and magnesium raw materials on the production of titanium dioxide by the chlorination process, eliminating the influence of high calcium and magnesium content in rich materials on boiling chlorination, achieving raw material adaptability, reducing production costs, and improving the technical and economic indicators of titanium dioxide chloride production.

[0007] The invention provides a method for eliminating the influence of high calcium and magnesium raw materials on the production of titanium dioxide by chlorination process, which comprises adding trivalent iron material to titanium-rich material for producing titanium dioxide by chlorination process, wherein the total content of CaO and MgO in the titanium-rich material is 1.5%-8.0%.

[0008] After adding trivalent iron material to the titanium-rich material used in the chlorination process to produce titanium dioxide, the reaction in the chlorination process of the titanium-rich material is as follows: the trivalent iron material is chlorinated to form ferric chloride, and at the same time, the calcium and magnesium oxides contained in the titanium-rich material are chlorinated to form calcium chloride and magnesium chloride, and then the ferric chloride reacts with calcium chloride and magnesium chloride to form ferric chloride calcium complex and ferric chloride magnesium complex respectively. The chemical reaction is: 2FeCl 3 +CaCl 2 =CaFe 2 Cl 8 , 2FeCl 3 +MgCl 2 =MgFe 2 Cl 8 Then the calcium ferric chloride complex and the magnesium ferric chloride complex are volatilized out of the chlorination furnace during the chlorination process at a temperature of 850~1050℃.

[0009] According to the present invention, trivalent iron material is added to a titanium-rich material with high calcium and magnesium contents. The ferric chloride calcium complex and ferric chloride magnesium complex generated in the chlorination process of the titanium-rich material are easily volatilized at 700-900° C., while the temperature of the chlorination process is 850-1050° C. Therefore, the ferric chloride calcium complex and the ferric chloride magnesium complex are volatilized in the chlorination process and overflow from the chlorination furnace together with the chlorination tail gas, thereby achieving the removal of calcium and magnesium oxides in the titanium-rich material in the titanium-rich material chlorination process step for producing titanium dioxide, avoiding the enrichment and agglomeration of calcium and magnesium oxides in the chlorination furnace after chlorination, eliminating the adverse effect of the high content of calcium and magnesium oxides in the titanium-rich material on the fluidized state during the chlorination operation, and also eliminating the need to pre-treat the titanium-rich material with high calcium and magnesium contents to reduce its calcium and magnesium contents, and not requiring the addition of additional process steps and equipment, thereby greatly reducing the production cost.

[0010] The molar ratio of the content of trivalent iron in the trivalent iron material to the total content of CaO and MgO in the titanium-rich material is 1 to 5:1. If the high calcium and magnesium chlorination raw material is directly put into the furnace, or the trivalent iron content is low, the calcium chloride and magnesium chloride generated after the calcium and magnesium reaction in the material are insufficient to form a complex with it, and the chlorination reaction system is discharged. The calcium and magnesium in the material accumulate in the chlorination furnace, and the chlorinated material will appear in the liquid phase in the furnace, unite with other materials, form large pieces of material, and cause a dead bed. It is necessary to stop the furnace and clean the material, and restart the furnace to resume production, which will inevitably affect the stability and smoothness of the chlorination operation and production efficiency, seriously affect the production of titanium dioxide chloride, and reduce the production technical and economic indicators; if the addition ratio is too high, the added material is titanium concentrate, the material grade is higher and the titanium slag is lower, which will inevitably affect the grade of the titanium-rich material entering the furnace, and the impurities brought in will increase, resulting in an increase in the cost of treating the chlorinated waste slag, affecting the entire economic benefits of titanium dioxide chloride production.

[0011] The ferric iron material is a material containing ferric iron or a mixture of ferric iron and titanium. The ferric iron reacts with chlorine to form ferric chloride, which forms a chlorinated complex with the chloride generated by the chlorination reaction of calcium and magnesium in the material. Moreover, ferric chloride is also a volatile substance. Under the chlorination operating temperature conditions, it overflows from the chlorination furnace together with the titanium tetrachloride tail gas generated by the reaction. Therefore, in the process of boiling chlorination, ferric chloride combines with calcium and magnesium chlorides and is discharged from the chlorination furnace, eliminating the adverse effects of high calcium and magnesium content in the material on the chlorination fluidization state.

[0012] The CaO content in the titanium-rich material is 0.12%~1.5%. The reactions of trivalent iron and calcium and magnesium oxides in the chlorination process are the same. Therefore, when the titanium-rich material contains less calcium oxide and more magnesium oxide, or more calcium oxide and less magnesium oxide, or even only contains calcium oxide or magnesium oxide, the addition of trivalent iron material can realize the formation of corresponding complexes between calcium and magnesium oxides and trivalent iron material during the chlorination process, and overflow the chlorination furnace together with the chlorination tail gas, eliminating the adverse effects of high calcium and magnesium content in the material on the chlorination fluidization state.

[0013] The titanium-rich material is selected from one or more of artificial rutile, natural rutile and high-titanium slag.

[0014] The methods of adding trivalent iron materials to the titanium-rich materials in the production of titanium dioxide by the chlorination process include: (1) Directly add ferric iron material; (2) Obtaining a titanium-rich material containing trivalent iron by oxidative modification of an iron-containing titanium-rich material, wherein the trivalent iron is the trivalent iron material added to the titanium-rich material for producing titanium dioxide by the chlorination process; (3) A titanium-rich material containing trivalent iron is obtained by oxidizing and modifying an iron-containing titanium-rich material, and a trivalent iron material is added at the same time.

[0015] The invention adds trivalent iron material to the raw material of boiling chlorination to produce titanium dioxide. After boiling chlorination, the ferric chloride forms ferric calcium chloride complex and ferric magnesium chloride complex with calcium chloride and magnesium chloride. The ferric calcium chloride complex and ferric magnesium chloride complex are volatilized into gas phase under chlorination operation temperature conditions, so that the ferric calcium chloride complex and ferric magnesium chloride complex overflow the chlorination furnace along with the chlorination tail gas, thereby eliminating the adverse effects of high calcium and magnesium content on the reaction in boiling chlorination. DETAILED DESCRIPTION

[0016] The embodiments of the present application will be described in more detail below. The application can be implemented in various forms, and should not be construed as being limited to the embodiments set forth herein, but rather these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the embodiments of the present application are only for exemplary purposes and are not intended to limit the scope of protection of the present application.

[0017] Embodiment 1: The tubular atmosphere furnace was installed in place, and the chlorine and nitrogen pipelines were connected. Quartz sand was used as a cushion layer to form an empty fluidized bed in the equipment. The electric furnace was turned on to raise the temperature of the fluidized bed reaction zone to 950°C and keep it warm. Nitrogen was used to replace the fluidized bed before adding materials, and nitrogen was continued to be passed. 4800g of high-titanium slag and 1600g of titanium concentrate were weighed and mixed to obtain reaction raw materials. 200g of reaction raw materials were weighed each time and 50g of petroleum coke was added as reaction materials. Then the reaction materials were transferred to the fluidized bed reactor. Nitrogen was used for protection during the process of adding materials and restoring the connection pipeline. When the temperature in the furnace recovered to 950°C, chlorine was passed in for chlorination reaction. During the chlorination process, the fluidization condition of the fluidized bed was observed. The high-titanium slag is a titanium-rich material, and its chemical composition is: TiO 2 86.13%, TFe 3.84%, CaO 0.93%, MgO 2.24%; titanium concentrate is a trivalent iron material, and its chemical composition is: TiO 2 56.1%, TFe 26.2%, CaO 0.11%, MgO 0.48%, Fe 2 O 3 32.8%; the chemical composition of the reaction materials entering the furnace is: TiO 2 80.12%, TFe 8.31%, CaO 0.77%, MgO 1.89%, Fe 2 O 3 6.56%.

[0018] Example 1 Iron-containing material titanium concentrate was added to the reaction material, and the molar ratio of iron-containing content in the titanium concentrate to the total content of CaO and MgO in the high-titanium slag was 1.34:1. After the introduction of chlorine, the fluidized bed remained in a good state. After each reaction for 15 minutes, the reaction material was continued to be added, and the material was reacted continuously for 15 times. The residue of the last reaction was collected and measured, and its chemical composition was analyzed and determined. The chlorination overflow rates of titanium, calcium, and magnesium in the material were calculated according to its mass and chemical composition, which were 95.7%, 92.6%, and 96.3%, respectively; at the same time, the chlorination process and the movement state of the tailings in the fluidized bed were observed. Under this condition, the material can maintain a good state in the fluidized bed.

[0019] Embodiment 2: The tubular atmosphere furnace was installed in place, and the chlorine and nitrogen pipelines were connected. Quartz sand was used as a cushion layer to form an empty fluidized bed in the equipment. The electric furnace was turned on to raise the temperature of the fluidized bed reaction zone to 1000°C and keep it warm. Nitrogen was used to replace the fluidized bed before adding materials, and nitrogen was continued to be passed. 4480g of high-titanium slag and 1920g of titanium concentrate were weighed and mixed to obtain reaction raw materials. 400g of reaction raw materials and 50g of petroleum coke were weighed each time as reaction materials. The reaction materials were transferred to the fluidized bed reactor. Nitrogen was used for protection during the process of adding materials and restoring the connection pipeline. When the temperature in the furnace recovered to 950°C, chlorine was passed in for chlorination reaction. During the chlorination process, the fluidized state of the fluidized bed was observed. The high-titanium slag is a titanium-rich material, and its chemical composition is: TiO 2 87.22%, TFe 3.27%, CaO 0.78%, MgO 2.32%; titanium concentrate is a trivalent iron material, and its chemical composition is: TiO 2 57.2%, TFe 27.1%, CaO 0.09%, MgO 0.42%, Fe 2 O 3 33.15%; the chemical composition of the reaction materials entering the furnace is: TiO 2 78.214%, TFe 10.42%, CaO 0.573%, MgO 1.75%, Fe 2 O 3 9.945%.

[0020] Example 2: Trivalent iron material titanium concentrate is added to the reaction material, and the molar ratio of the trivalent iron content in the titanium concentrate to the total content of CaO and MgO in the high-titanium slag is 2.3:1. After the introduction of chlorine, the fluidized bed still maintains a good state. After each reaction for 25 minutes, the mixed material is continued to be added, and the material is reacted continuously for 15 times. The residue of the last reaction is collected and measured, and its chemical composition is analyzed and determined. The chlorination overflow rates of titanium, calcium and magnesium in the material are calculated according to their mass and chemical composition, which are 95.5%, 98.6% and 99.7% respectively. At the same time, the chlorination process and the movement state of the tailings in the fluidized bed are observed. Under this condition, the material can maintain a good state in the fluidized bed.

[0021] Embodiment 3: In the chlorination process of boiling titanium dioxide, high-titanium slag with a high iron content is purchased as a chlorination raw material. Before use, it is subjected to an oxidation modification treatment to obtain oxidized high-titanium slag. The specific process is that before entering the chlorination furnace, diesel or natural gas is used as a combustion raw material. When air is introduced as a combustion-supporting and oxidizing medium, a rotary kiln is used to perform high-temperature oxidation treatment on the high-titanium slag. The iron in the high-titanium slag undergoes an oxidation reaction with oxygen in the air under aerobic conditions to directly form iron oxide. In the chlorination process, the iron oxide after the high-titanium slag iron oxidation reacts with CaO and MgO therein to form a chloride complex. The high-titanium slag is a titanium-rich material, and its chemical composition before and after oxidation is as follows: before oxidation of the high-titanium slag: CaO 0.87%, MgO1.97%; after oxidation of the high-titanium slag: CaO 0.84%, MgO 1.95%, Fe 2 O 3 7.90%.

[0022] Embodiment 3 is to use high-titanium slag with high iron content to oxidize to form high-titanium slag containing trivalent iron for self-reaction, and use the iron oxide formed by oxidation of the iron contained in the high-titanium slag as the trivalent iron material, and form a chlorinated complex with CaO and MgO therein after chlorination, and overflow the chlorination furnace with the chlorinated tail gas, thereby eliminating the influence of the high-calcium-magnesium high-titanium slag on the chlorination state of boiling chlorination; wherein the molar ratio of the trivalent iron content in the oxidized high-titanium slag to the total content of CaO and MgO therein is 1.03:1, and after the introduction of chlorine, the fluidized bed still maintains a good state. After 30 hours of reaction, the residue of the last reaction is collected and measured, and its chemical composition is analyzed and determined. According to its mass and chemical composition, the chlorination overflow rates of titanium, calcium and magnesium in the material are calculated, which are 95.9%, 97.4% and 98.7% respectively; at the same time, the chlorination process and the movement state of the tailings in the fluidized bed are observed. Under this condition, the material can maintain a good state in the fluidized bed, and the fluidized bed still maintains a good state.

[0023] Embodiment 4: The tubular atmosphere furnace was installed in place, chlorine and nitrogen pipelines were connected, quartz sand was used as a cushion layer, and the equipment formed an empty fluidized bed. The electric furnace was turned on to raise the temperature of the fluidized bed reaction zone to 1000°C and keep it warm. Nitrogen was used to replace the fluidized bed before adding materials, and nitrogen was continued to be passed. 4480g of the oxidized high-titanium slag of Example 3 and 1920g of titanium concentrate were weighed and mixed to obtain reaction raw materials. 400g of the reaction raw materials and 50g of petroleum coke with high-titanium slag were weighed each time as reaction materials. The reaction materials were transferred to the fluidized bed reactor. Nitrogen was used for protection during the process of adding materials and restoring the connection pipeline. When the temperature in the furnace recovered to 950°C, chlorine was passed in for chlorination reaction. During the chlorination process, the fluidized state of the fluidized bed was observed. The oxidized high-titanium slag was a titanium-rich material, and the iron oxide formed after the iron contained in the high-titanium slag was oxidized as a trivalent iron material, and its chemical composition was: TiO 2 87.11%, TFe 3.27%, CaO 0.84%, MgO 1.95%, Fe 2 O 3 7.9%; titanium concentrate is a trivalent iron material, and its chemical composition is: TiO 2 57.2%, TFe 27.1%, CaO 0.09%, MgO 0.42%, Fe 2 O 3 33.15%; the chemical composition of the reaction materials entering the furnace is: TiO 2 78.14%, TFe 10.42%, CaO 0.615%, MgO 1.42%, Fe 2 O 3 15.48%.

[0024] Example 4 is to use high-titanium slag with high iron content to form high-titanium slag containing trivalent iron as the reaction raw material, the iron oxide formed by oxidation of the iron contained in the high-titanium slag is used as the trivalent iron material, and the trivalent iron material titanium concentrate is added, the molar ratio of the trivalent iron content in the reaction material to the total content of CaO and MgO is 4.21:1, after the introduction of chlorine gas, the fluidized bed still maintains a good state, after each reaction for 25 minutes, continue to add the mixed material, and react the material for 15 times continuously. The residue of the last reaction is collected and measured, and its chemical composition is analyzed and determined. The chlorination overflow rates of titanium, calcium, and magnesium in the material are calculated according to their mass and chemical composition, which are 95.3%, 99.6%, and 99.3%, respectively; at the same time, the chlorination process and the movement state of the tailings in the fluidized bed are observed. Under this condition, the material can maintain a good state in the fluidized bed.

[0025] Comparative Example 1: Install the tubular atmosphere furnace in place, connect the chlorine and nitrogen pipelines, use quartz sand as a cushion layer, make the equipment form an empty fluidized bed, turn on the electric furnace, raise the temperature of the fluidized bed reaction zone to 950°C, and keep it warm. Use nitrogen to replace the fluidized bed before adding materials, and continue to pass nitrogen. Weigh 200g of high-titanium slag and add 50g of petroleum coke as the reaction material, and then transfer the reaction material to the fluidized bed reactor. Use nitrogen for protection during the process of adding materials and restoring the connection pipeline. When the temperature in the furnace returns to 950°C, pass chlorine for chlorination reaction. During the chlorination process, observe the fluidization condition of the fluidized bed; the high-titanium slag is a titanium-rich material, and its chemical composition is: TiO 2 86.13%, TFe 3.84%, CaO 0.93%, MgO 2.24%.

[0026] Comparative Example 1 does not add trivalent iron material, and observes the chlorination process and the movement state of tailings in the fluidized bed: before chlorine is introduced, the reaction material is in a fluidized state in the fluidized bed, and the fluidization is good, but after the chlorine is introduced, a dead bed immediately appears in the fluidized bed, and the fluidized reaction material material quickly forms a block, sintered in the fluidized bed, and is stationary, and the chlorination reaction effect is poor. The chlorine introduced has a short contact time due to the reaction material passing through the static solid, and there is no reaction to immediately overflow the reactor with the tail gas, resulting in chlorination failure, and the furnace must be shut down, and it is necessary to rebuild the bed for reaction; at the same time, the residue of the last reaction is collected and measured, and its chemical composition is analyzed and determined. According to its mass and chemical composition, the titanium, calcium, and magnesium chlorination overflow rates in the material are calculated, respectively: 4.7%, 3.5%, and 7.8%, respectively, indicating that after the dead bed appears in the fluidized bed, the material is sintered, the chlorination reaction stops, the material does not undergo chlorination reaction, and chlorine overflows with the tail gas, and a chlorine run accident occurs.

[0027] In summary, it can be seen from the above embodiments and comparative examples that a trivalent iron material is added to a titanium-rich material with a high calcium and magnesium content, a chlorination reaction occurs, ferric chloride is formed, and a complex reaction occurs with calcium chloride and magnesium chloride to generate a calcium ferric chloride complex and a magnesium ferric chloride complex, and the chlorinated complex can be effectively overflowed, eliminating the adverse effects of high calcium and magnesium content on the fluidization process of the chlorination reaction; and the chlorination yield of titanium is basically unchanged, proving that the present method will not have an adverse effect on the chlorinated product; at the same time, the trivalent iron material is added in the same way, and as the content of the trivalent iron material increases, the chlorination overflow rate of calcium and magnesium increases until all overflow the chlorination furnace, and the fluidized state of the chlorination process is good, which provides a new process for the production of titanium dioxide by the chloride process and reduces production costs.

[0028] In addition, the titanium-rich material uses one or more of artificial rutile, natural rutile, and high-titanium slag, and the total content of CaO and MgO is 1.5%~8.0%, which is the same condition as the titanium-rich material using high-titanium slag. The molar ratio of the content of trivalent iron in the added trivalent iron material to the total content of CaO and MgO in the titanium-rich material is 1~5:1. Both can achieve chlorination reaction between iron and calcium and magnesium in the chlorination process to form ferric calcium chloride complex and ferric magnesium chloride complex, and overflow from the chlorination furnace, eliminating the adverse effects of high calcium and magnesium contents on the reaction in boiling chlorination.

[0029] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in this application, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for eliminating the influence of high calcium and magnesium raw materials on the production of titanium dioxide by the chloride process, characterized in that: Trivalent iron material is added to the titanium-rich material for producing titanium dioxide by the chlorination process, wherein the total content of CaO and MgO in the titanium-rich material is 1.5%~8.0%.

2. The method for eliminating the influence of high calcium and magnesium raw materials on the production of titanium dioxide by the chloride process according to claim 1, characterized in that: After adding trivalent iron material to the titanium-rich material for producing titanium dioxide by the chlorination process, the reaction in the chlorination process of the titanium-rich material is as follows: the trivalent iron material is chlorinated to form ferric chloride, and at the same time, the calcium and magnesium oxides contained in the titanium-rich material are chlorinated to form calcium chloride and magnesium chloride, and then the ferric chloride reacts with calcium chloride and magnesium chloride to form ferric calcium chloride complex and ferric magnesium chloride complex, respectively, and the chemical reaction is: 2FeCl3+CaCl2= CaFe2Cl8, 2FeCl3+MgCl2= MgFe2Cl8, and then the ferric calcium chloride complex and ferric magnesium chloride complex evaporate out of the chlorination furnace during the chlorination process at a temperature of 850~1050℃.

3. The method for eliminating the influence of high calcium and magnesium raw materials on the production of titanium dioxide by the chlorination process according to claim 1, characterized in that: The molar ratio of the content of trivalent iron in the trivalent iron material to the total content of CaO and MgO in the titanium-rich material is 1-5:

1.

4. A method for eliminating the influence of high calcium and magnesium raw materials on the production of titanium dioxide by the chloride process according to any one of claims 1 to 3, characterized in that: The ferric iron material is a material containing ferric iron or a mixture containing ferric iron and titanium.

5. A method for eliminating the influence of high calcium and magnesium raw materials on the production of titanium dioxide by chloride process according to any one of claims 1 to 3, characterized in that: The CaO content in the titanium-rich material is 0.12% to 1.5%.

6. The method for eliminating the influence of high calcium and magnesium raw materials on the production of titanium dioxide by the chlorination process according to claim 5, characterized in that: The titanium-rich material is selected from one or more of artificial rutile, natural rutile and high-titanium slag.

7. The method for eliminating the influence of high calcium and magnesium raw materials on the production of titanium dioxide by the chloride process according to claim 1, characterized in that: The methods of adding trivalent iron materials to the titanium-rich materials in the production of titanium dioxide by the chlorination process include: (1) Directly add ferric iron material; (2) Obtaining a titanium-rich material containing trivalent iron by oxidative modification of an iron-containing titanium-rich material, wherein the trivalent iron is the trivalent iron material added to the titanium-rich material for producing titanium dioxide by the chlorination process; (3) A titanium-rich material containing trivalent iron is obtained by oxidizing and modifying an iron-containing titanium-rich material, and a trivalent iron material is added at the same time.