Energy-saving and pollution-reducing method for calcination process of titanium dioxide by sulfuric acid method

Abstract

The present application belongs to the technical field of energy saving and consumption reduction of titanium dioxide production, and particularly relates to a method for energy saving and pollution reduction in the calcination process of sulfuric acid method titanium dioxide. The present application realizes the cascade utilization of high-temperature to medium-low-temperature waste heat through the integrated scheme of "preheating and quality improvement + oxygen-rich calcination + tail gas synergistic desulfurization and denitrification + resource utilization of by-products", that is, the calcination tail gas (1000-1100℃) is first used to generate steam for production through a waste heat boiler, and then is used for preheating and drying metatitanic acid after being cooled, thereby realizing the cascade utilization of high-temperature to medium-low-temperature waste heat, and simultaneously, the oxygen-rich combustion improves the fuel efficiency, the natural gas combustion is more sufficient, the energy consumption per unit product is reduced by 30-40%, and the ammonia method is used to simultaneously remove SO2 and NO x in a single reactor, the desulfurization efficiency is greater than or equal to 95%, the denitrification efficiency is greater than or equal to 85%, the concentration of dust in the tail gas after being removed by a bag filter is less than or equal to 10 mg / Nm3 for emission, the unity of environmental benefits and economic benefits is realized, and a new path is provided for the green upgrading of the sulfuric acid method titanium dioxide industry.

Description

Technical Field

[0001] This invention belongs to the field of energy conservation and emission reduction technology in titanium dioxide production, specifically relating to an energy-saving and pollution-reducing method for the calcination process of sulfuric acid titanium dioxide. Background Technology

[0002] The sulfuric acid process is currently the main technology for titanium dioxide production in my country. Its calcination step, a core process for converting metatitanic acid (H₂TiO₃) into pigment-grade titanium dioxide (TiO₂), has long faced the dual challenges of high energy consumption and heavy pollution. With the deepening of national energy conservation and emission reduction policies, the industry has placed unprecedentedly stringent requirements on the greening and low-carbon transformation of production processes. Traditional technologies and their improvements still have systemic shortcomings in addressing these challenges.

[0003] Traditional rotary kiln calcination processes require temperatures of 850-950℃, resulting in extremely high energy consumption. Industry analysis indicates that the calcination heat consumption per ton of titanium dioxide can reach as high as 3.2108 million kcal, with up to 74.5% of this heat used to evaporate moisture in metatitanic acid and carried away directly by the exhaust gas. Only about 25% of the heat is actually used for material decomposition and crystal transformation. This not only leads to significant energy waste but also results in persistently high overall energy consumption per unit of product, far exceeding international advanced levels (2.5-3 million kcal / ton of titanium dioxide). Furthermore, the high-temperature exhaust gas produced in this process has a complex composition, containing high concentrations of sulfur dioxide (SO2, 500-1500 mg / Nm³) and nitrogen oxides (NOx). x (300-800 mg / Nm³) and titanium dioxide dust. Traditional treatment methods often use simple methods such as "cyclone dust collector + water spray desulfurization", with a desulfurization efficiency of only 60-70%, and cannot effectively remove NO. x This technology is completely unable to meet the increasingly stringent ultra-low emission standards. Energy consumption and environmental protection have become two major bottlenecks restricting the sustainable development of the sulfuric acid process titanium dioxide industry.

[0004] To address these issues, the industry has proposed several improvement solutions, but these solutions are mostly localized optimizations and have failed to form a collaborative solution from source to end.

[0005] In terms of energy conservation and consumption reduction, existing technologies mainly focus on waste heat recovery and raw material pretreatment. Patent CN102080928A discloses a method for utilizing the thermal energy of rotary kiln calcination flue gas. Its core lies in using high-temperature flue gas to concentrate 20% of the waste acid in the production process to 30%, and returning part of the purified flue gas back into the kiln for reuse. Although this method achieves preliminary utilization of waste heat and recovery of materials (kiln ash), its energy-saving perspective is limited to the tail gas end and does not address the root cause of the high energy consumption in the calcination process itself.

[0006] Theoretical research and practice have shown that strengthening raw material pretreatment is a more effective energy-saving approach. For example, using a diaphragm press to increase the solid content of metatitanic acid slurry from 35% to over 55% can significantly reduce the heat required for water evaporation in the kiln, theoretically reducing heat consumption in the calcination section by approximately 27.9%. Other short-process technologies achieve cost reduction and efficiency improvement by eliminating the titanium liquid concentration step and optimizing salt treatment and calcination conditions (such as controlling the calcination temperature at 840℃). However, these methods mostly focus on improvements in single stages and lack deep integration with the calcination kiln and exhaust gas system for the cascade utilization of thermal energy.

[0007] In terms of exhaust gas treatment, existing technologies face the dilemma of low treatment efficiency, high cost, and insufficient resource utilization.

[0008] Traditional and improved desulfurization technologies, such as the limestone-gypsum method combined with the sodium alkali method, can improve desulfurization efficiency to meet emission standards, but they are essentially still "end-of-pipe treatments" that convert pollutants into new solid wastes (such as gypsum), failing to achieve resource recovery and unable to synergistically denitrify.

[0009] Resource utilization technologies, such as patent CN117018859A, propose a method to produce sulfuric acid from sulfur-containing tail gas through catalytic desulfurization and utilize the waste heat of the tail gas to dry the raw materials, embodying the idea of ​​"turning waste into treasure." However, this solution mainly targets SO2 and still does not address NO. x The problem of simultaneous removal is present, and the process chain is long, resulting in high system integration complexity.

[0010] In summary, existing technologies exhibit a disconnect between "energy saving" and "pollution reduction." Therefore, there is an urgent need to provide a comprehensive new process for energy saving and pollution reduction in the sulfuric acid process for titanium dioxide calcination, in order to promote the green upgrading of this process. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide an energy-saving and pollution-reducing method for the calcination process of sulfuric acid titanium dioxide. Through an integrated solution of "preheating and upgrading + oxygen-enriched calcination + tail gas co-desulfurization and denitrification + by-product resource utilization", the energy consumption of calcination is reduced, the tail gas treatment efficiency is improved, and a win-win situation of energy saving and environmental protection is achieved.

[0012] The technical solution adopted is as follows: A method for energy conservation and pollution reduction in the calcination process of sulfuric acid titanium dioxide includes the following steps: (1) Preheating and upgrading of metatitanic acid: The metatitanic acid is sent to a paddle dryer for drying, and the residual heat of the calcination tail gas is used to preheat the metatitanic acid; the water volatilized during the preheating process is recovered by condensation to avoid entering the calcination kiln and affecting the calcination efficiency. (2) Oxygen-enriched calcination: The preheated metatitanic acid is fed into the rotary kiln, and oxygen-enriched air is introduced as the combustion-supporting gas. Natural gas is used as the fuel. The temperature of the front and rear sections of the rotary kiln is controlled to carry out oxygen-enriched calcination. Natural gas is used as the fuel. Oxygen-enriched combustion can improve combustion efficiency, reduce fuel consumption, and reduce exhaust emissions. (3) Waste heat recovery from tail gas: The high-temperature tail gas generated by calcination is first fed into the waste heat boiler to generate saturated steam, which is used for steam production in the enterprise; the cooled tail gas is then sent to the paddle dryer to provide heat for the preheating of metatitanic acid, and further recover the waste heat tail gas. (4) Co-processing of tail gas desulfurization and denitrification: The tail gas after waste heat recovery enters the co-processing desulfurization and denitrification reactor. Ammonia water is injected into the reactor as an absorbent, and a catalyst is added at the same time. The reaction temperature and pressure are controlled so that the ammonia water reacts with SO2 to produce ammonium sulfate, which then reacts with NO. x The reaction produces ammonium nitrate; the exhaust gas after the reaction is filtered by a bag filter to remove dust and is discharged in compliance with standards. (5) By-product recovery: The slurry produced by synergistic desulfurization and denitrification is filtered and dried to obtain mixed ammonium salt.

[0013] Preferably, in step (1), the moisture content of metatitanic acid is 30-40%, and the moisture content after drying is ≤5%; the metatitanic acid is preheated to 150-200℃ using the residual heat of the calcination tail gas.

[0014] Preferably, in step (2), the oxygen content in the oxygen-enriched air is 25-30 wt%.

[0015] Preferably, in step (2), the temperature of the front section of the rotary kiln is controlled at 800-850℃ and the temperature of the rear section is controlled at 900-950℃; the oxygen-enriched calcination time is 30-40 min.

[0016] Preferably, in step (3), the temperature of the high-temperature tail gas generated by calcination is 1000-1100℃; and the pressure of the saturated steam generated is 0.8-1.0 MPa.

[0017] Preferably, in step (3), the temperature of the cooled exhaust gas is 300-350℃; the calcined exhaust gas in step (1) is exhaust gas cooled to 300-350℃.

[0018] Preferably, in step (4), the temperature of the tail gas after waste heat recovery is 150-200℃; the synergistic desulfurization and denitrification reactor adds V2O5-TiO2 catalyst while injecting ammonia water to achieve SO2 and NO x Highly efficient synchronous removal.

[0019] Preferably, in step (4), the mass fraction of ammonia water is 20-25%, and the added catalyst is 0.5-1.0% of the mass of ammonia water; the reaction temperature is controlled at 180-220℃ and the pressure at 0.1-0.2 MPa; and the dust content after filtration is ≤10mg / Nm³.

[0020] Preferably, the ammonia injection acceleration rate is related to the SO2 and NO content in the exhaust gas. x Concentration is adjusted in a coordinated manner to ensure desulfurization efficiency ≥95% and denitrification efficiency ≥90%.

[0021] Preferably, in step (5), the mixed ammonium salt includes ammonium sulfate and ammonium nitrate, which are recycled as raw materials for compound fertilizer.

[0022] The inner wall lining of the rotary kiln is made of high-temperature resistant refractory material (Al2O3-SiO2), which extends the service life of the equipment.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In terms of energy saving, the method of the present invention can enable deep recovery and utilization of multi-stage waste heat, which can significantly reduce system energy consumption.

[0024] For the first time, the calcination tail gas (1000-1100℃) is first used to generate production steam in a waste heat boiler, and then cooled down for use in the preheating and drying of metatitanic acid. This achieves the cascade utilization of waste heat from high temperature to medium and low temperature. At the same time, oxygen-enriched combustion improves fuel efficiency, makes natural gas burn more completely, and reduces the energy consumption per unit product by 30-40%, from the traditional 800-1000MJ / t to 500-650MJ / t. After preheating, the moisture content of metatitanic acid is reduced from 30-40% to ≤5%, which significantly reduces the heat required for moisture evaporation during the calcination stage and reduces the heat load of the rotary kiln by 15-20%. With the same output, the total amount of combustion air is reduced, thereby reducing exhaust emissions and lowering the energy consumption of the subsequent exhaust gas treatment system.

[0025] (2) In terms of pollution reduction, this invention innovatively adopts an ammonia-based synergistic desulfurization and denitrification process to simultaneously remove SO2 and NO in a single reactor. x The desulfurization efficiency is ≥95%, and the denitrification efficiency is ≥85%, far exceeding that of traditional segmented treatment processes. By adding a V2O5-TiO2 catalyst, a highly efficient reaction is achieved within a medium-temperature window of 180-220℃, avoiding the increased energy consumption required by traditional SCR processes which require high temperatures (300-400℃). Pollutants are utilized as resources, achieving near-zero waste emissions.

[0026] This invention converts desulfurization and denitrification products into a mixed fertilizer of ammonium sulfate and ammonium nitrate, realizing the recovery and utilization of sulfur and nitrogen resources and solving the problem of solid waste generated by the traditional limestone-gypsum process. The concentration of dust in the exhaust gas after passing through a bag filter is ≤10mg / Nm³, far below the national emission standard (30mg / Nm³).

[0027] This invention achieves pollution prevention and control throughout the entire process. During the preheating stage, moisture is condensed and recovered, preventing moisture from entering the rotary kiln and affecting calcination stability and increasing exhaust gas humidity. Oxygen-enriched combustion reduces the introduction of nitrogen, thereby suppressing thermal NOx. x The generation of these pollutants reduces the amount of pollutants produced at the source.

[0028] (3) In terms of comprehensive benefits, this invention has formed a complete technical system of "waste heat utilization - oxygen-enriched high-efficiency combustion - pollutant synergistic removal - by-product resource utilization" through process coupling and system optimization. Under the same production scale, the overall energy consumption can be reduced by 20-25%, the total pollutant emissions can be reduced by 40-50%, and the by-products can also generate additional economic benefits, realizing the unity of environmental and economic benefits, and providing a practical and feasible technical path for the green upgrading of the sulfuric acid process titanium dioxide industry. Attached Figure Description

[0029] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0030] The accompanying drawings are for illustrative purposes only; to enable those skilled in the art to better understand the technical solutions of the present invention, the preferred embodiments of the present invention are described below in conjunction with specific examples, but should not be construed as limiting the present patent.

[0031] Unless otherwise specified, the test methods or experimental methods described in the following examples are conventional methods; the materials and instruments used are obtained from conventional commercial sources or prepared by conventional methods unless otherwise specified.

[0032] Example 1 An energy-saving and pollution-reducing method for the calcination process of sulfuric acid titanium dioxide, the specific steps of which are as follows: (1) Preheating and upgrading of metatitanic acid: Metatitanic acid with a moisture content of 30% is fed into a paddle dryer and preheated to 150°C using the residual heat of the calcination tail gas and dried to a moisture content of ≤5%; the water volatilized during the preheating process is condensed and recovered to avoid entering the calcination kiln and affecting the calcination efficiency.

[0033] (2) Oxygen-enriched calcination: The preheated metatitanic acid is fed into the rotary kiln and oxygen-enriched air (oxygen content 25wt%) is introduced as the combustion-supporting gas. Natural gas is selected as the fuel. The temperature of the front section of the rotary kiln is controlled at 800℃ and the temperature of the rear section is controlled at 900℃. The material residence time is 30min. Oxygen-enriched combustion can improve combustion efficiency, reduce fuel consumption, and reduce exhaust emissions.

[0034] (3) Waste heat recovery from tail gas: The high-temperature tail gas (around 1000℃) generated by calcination is first fed into the waste heat boiler to generate saturated steam of around 0.8MPa, which can be used for steam production in enterprises; the tail gas cooled to around 300℃ is then sent to the paddle dryer to provide heat for the preheating of metatitanic acid and further recover waste heat.

[0035] (4) Co-processing of tail gas desulfurization and denitrification: The tail gas (temperature around 150℃) after waste heat recovery enters the co-processing desulfurization and denitrification reactor. Ammonia water (mass fraction 20%) is injected into the reactor as an absorbent, and 0.5% catalyst (V2O5-TiO2) is added at the same time. The reaction temperature is controlled at 180℃ and the pressure at 0.1MPa. The ammonia water reacts with SO2 to produce ammonium sulfate, which reacts with NO... x The reaction produces ammonium nitrate; the exhaust gas is filtered by a bag filter to remove dust (dust content ≤10mg / Nm³), meeting emission standards. Based on monitored SO2 and NO... x The concentration of ammonia water is adjusted to control the injection rate, ensuring a desulfurization efficiency of ≥95% and a denitrification efficiency of ≥90%.

[0036] (5) By-product recovery: The slurry produced by synergistic desulfurization and denitrification is filtered and dried to obtain mixed ammonium salt (ammonium sulfate + ammonium nitrate), which can be recycled as raw material for compound fertilizer.

[0037] The oxygen-enriched air is produced by an oxygen generator, and the oxygen content can be adjusted in real time according to the calcination effect.

[0038] Example 2 An energy-saving and pollution-reducing method for the calcination process of sulfuric acid titanium dioxide, the specific steps of which are as follows: (1) Preheating and upgrading of metatitanic acid: Metatitanic acid with a moisture content of 40% is fed into a paddle dryer and preheated to 200°C using the residual heat of the calcination tail gas and dried to a moisture content of ≤5%; the water volatilized during the preheating process is condensed and recovered to avoid entering the calcination kiln and affecting the calcination efficiency.

[0039] (2) Oxygen-enriched calcination: The preheated metatitanic acid is fed into the rotary kiln and oxygen-enriched air (oxygen content 30wt%) is introduced as the combustion-supporting gas. Natural gas is selected as the fuel. The temperature of the front section of the rotary kiln is controlled at 850℃ and the temperature of the rear section is controlled at 950℃. The material residence time is 40min. Oxygen-enriched combustion can improve combustion efficiency, reduce fuel consumption, and reduce exhaust emissions.

[0040] (3) Waste heat recovery from tail gas: The high-temperature tail gas (around 1100℃) generated by calcination is first fed into the waste heat boiler to generate saturated steam of around 1.0MPa, which can be used for steam production in enterprises; the tail gas cooled to around 350℃ is then sent to the paddle dryer to provide heat for the preheating of metatitanic acid and further recover waste heat.

[0041] (4) Co-processing of tail gas desulfurization and denitrification: The tail gas (temperature around 200℃) after waste heat recovery enters the co-processing desulfurization and denitrification reactor. Ammonia water (mass fraction 25%) is injected into the reactor as an absorbent, and 1.0% catalyst (V2O5-TiO2) is added at the same time. The reaction temperature is controlled at 220℃ and the pressure at 0.2MPa. The ammonia water reacts with SO2 to produce ammonium sulfate, which reacts with NO... x The reaction produces ammonium nitrate; the exhaust gas is filtered by a bag filter to remove dust (dust content ≤10mg / Nm³), meeting emission standards. Based on monitored SO2 and NO... x The concentration of ammonia water is adjusted to control the injection rate, ensuring a desulfurization efficiency of ≥95% and a denitrification efficiency of ≥90%.

[0042] (5) By-product recovery: The slurry produced by synergistic desulfurization and denitrification is filtered and dried to obtain mixed ammonium salt (ammonium sulfate + ammonium nitrate), which can be recycled as raw material for compound fertilizer.

[0043] The oxygen-enriched air is produced by an oxygen generator, and the oxygen content can be adjusted in real time according to the calcination effect.

[0044] Application Example 1 This method was implemented using the calcination process of a 50,000-ton-per-year sulfuric acid process titanium dioxide production line as the target for modification: Metatitanic acid preheating and upgrading: Metatitanic acid with a moisture content of 35% is fed into a paddle dryer, preheated to 180℃ using the waste heat of calcination tail gas, and dried to a moisture content of 4.2%, with a 90% condensation and recovery rate of volatile water; Oxygen-enriched calcination: Preheated metatitanic acid is fed into a rotary kiln, and oxygen-enriched air with an oxygen content of 28% is introduced. The natural gas consumption is 120 Nm³ / t of product. The temperature of the front section of the rotary kiln is 820℃, the temperature of the rear section is 930℃, the material residence time is 35 min, and the purity of the titanium dioxide after calcination is 98.5%. Waste heat recovery from exhaust gas: High-temperature exhaust gas at 1050℃ is fed into a waste heat boiler to generate 0.9MPa saturated steam (steam production of 0.8t / t product), which is used for post-processing pulping; the exhaust gas cooled to 320℃ enters a paddle dryer, and after preheating, the exhaust gas temperature drops to 180℃. Co-processing of tail gas desulfurization and denitrification: 22% ammonia water is injected into the co-processing reactor, and 0.8% V2O5-TiO2 catalyst is added. The reaction temperature is 200℃ and the pressure is 0.15MPa. Before treatment, the SO2 concentration in the tail gas is 1200mg / Nm³, and the NO concentration is... xAfter treatment, the concentration of SO2 was 45 mg / Nm³ and the concentration of NO was 600 mg / Nm³. x Concentration 52 mg / Nm³, dust content 8 mg / Nm³; Byproduct recovery: The slurry was pressure filtered and dried to obtain mixed ammonium salts (75% ammonium sulfate and 23% ammonium nitrate), with a recovery rate of 98% and 0.065 tons of ammonium salts recovered per ton of product.

[0045] Implementation results: Energy consumption per unit product decreased from 920MJ / t to 580MJ / t, saving 4.8 million yuan in natural gas costs annually; exhaust emissions fully met standards, and by-product ammonium salt generated 1.95 million yuan in economic benefits annually; the investment payback period for equipment upgrades was 1.5 years.

[0046] The results of comparing the application example 1 of the present invention with the conventional process are shown in Tables 1-3.

[0047] (1) Energy consumption comparison, the results are shown in Table 1.

[0048] Table 1. Energy consumption comparison between application example 1 of the present invention and conventional processes. (2) Comparison of exhaust pollutant emission concentrations, the results are shown in Table 2.

[0049] Table 2 Comparison of exhaust gas pollutant emission concentrations between Example 1 of the present invention and conventional processes (3) Comparison of by-product recovery volume and economic benefits trend, the results are shown in Table 3.

[0050] Table 3 Comparison of the recycling benefits of Application Example 1 of the present invention with traditional processes The amount of by-products recovered is linearly positively correlated with the production scale. Based on an ammonium salt price of 3,000 yuan / ton, a scale of 50,000 tons / year would generate an annual revenue increase of 1.95 million yuan, reflecting the value of resource utilization.

[0051] The method of this invention produces exhaust emissions of approximately 75% (oxygen-enriched combustion emission reduction), while traditional processes produce 100% exhaust emissions, thus achieving the dual benefits of energy saving and pollution reduction.

[0052] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for energy conservation and pollution reduction in the calcination process of sulfuric acid titanium dioxide, characterized in that, Includes the following steps: (1) Preheating and upgrading of metatitanic acid: The metatitanic acid is sent to a paddle dryer for drying, and the residual heat of the calcination tail gas is used to preheat the metatitanic acid; the water volatilized during the preheating process is recovered by condensation. (2) Oxygen-enriched calcination: The preheated metatitanic acid is fed into the rotary kiln, and oxygen-enriched air is introduced as the combustion gas. Natural gas is used as the fuel. The temperature of the front and rear sections of the rotary kiln is controlled to carry out oxygen-enriched calcination. (3) Waste heat recovery from tail gas: The high-temperature tail gas generated by calcination is first fed into the waste heat boiler to generate saturated steam, which is used for steam production in the enterprise; the cooled tail gas is then sent to the paddle dryer to provide heat for the preheating of metatitanic acid, and further recover the waste heat tail gas. (4) Co-processing of tail gas desulfurization and denitrification: The tail gas after waste heat recovery enters the co-processing desulfurization and denitrification reactor. Ammonia water is injected into the reactor as an absorbent, and a catalyst is added at the same time. The reaction temperature and pressure are controlled so that the ammonia water reacts with SO2 to produce ammonium sulfate, which then reacts with NO. x The reaction produces ammonium nitrate; the exhaust gas after the reaction is filtered by a bag filter to remove dust and is discharged in compliance with standards. (5) By-product recovery: The slurry produced by synergistic desulfurization and denitrification is filtered and dried to obtain mixed ammonium salt.

2. The energy-saving and pollution-reducing method for the calcination process of sulfuric acid titanium dioxide according to claim 1, characterized in that, In step (1), the moisture content of metatitanic acid is 30-40%, and the moisture content after drying is ≤5%; the metatitanic acid is preheated to 150-200℃ using the residual heat of the calcination tail gas.

3. The energy-saving and pollution-reducing method for the calcination process of sulfuric acid titanium dioxide according to claim 1, characterized in that, In step (2), the oxygen content in the oxygen-enriched air is 25-30 wt%.

4. The energy-saving and pollution-reducing method for the calcination process of sulfuric acid titanium dioxide according to claim 1, characterized in that, In step (2), the temperature of the front section of the rotary kiln is controlled at 800-850℃ and the temperature of the rear section is controlled at 900-950℃; the oxygen-enriched calcination time is 30-40 min.

5. The energy-saving and pollution-reducing method for the calcination process of sulfuric acid titanium dioxide according to claim 1, characterized in that, In step (3), the temperature of the high-temperature tail gas generated by calcination is 1000-1100℃; the pressure of the saturated steam generated is 0.8-1.0 MPa.

6. The energy-saving and pollution-reducing method for the calcination process of sulfuric acid titanium dioxide according to claim 1, characterized in that, In step (3), the temperature of the cooled exhaust gas is 300-350℃; the calcined exhaust gas mentioned in step (1) is the exhaust gas cooled to 300-350℃.

7. The energy-saving and pollution-reducing method for the calcination process of sulfuric acid titanium dioxide according to claim 1, characterized in that, In step (4), the temperature of the tail gas after waste heat recovery is 150-200℃; the synergistic desulfurization and denitrification reactor adds V2O5-TiO2 catalyst while injecting ammonia water to achieve SO2 and NO x Highly efficient synchronous removal.

8. The energy-saving and pollution-reducing method for the calcination process of sulfuric acid titanium dioxide according to claim 1, characterized in that, In step (4), the mass fraction of ammonia water is 20-25%, and the added catalyst is 0.5-1.0% of the mass of ammonia water; the reaction temperature is controlled at 180-220℃ and the pressure is 0.1-0.2 MPa; the dust content after filtration is ≤10mg / Nm³.

9. A method for energy conservation and pollution reduction in the calcination process of sulfuric acid titanium dioxide according to claim 8, characterized in that, Ammonia injection acceleration rate and SO2 and NO in exhaust gas x Concentration is adjusted in a coordinated manner to ensure desulfurization efficiency ≥95% and denitrification efficiency ≥90%.

10. The energy-saving and pollution-reducing method for the calcination process of sulfuric acid titanium dioxide according to claim 1, characterized in that, In step (5), the mixed ammonium salts include ammonium sulfate and ammonium nitrate, which are recycled as raw materials for compound fertilizer.

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