Preparation method of hydrolyzed metatitanic acid with narrow particle size distribution and high-whiteness rutile crude product

Abstract

The invention discloses a preparation method of hydrolyzed metatitanic acid with narrow particle size distribution and a high-whiteness rutile crude product, and belongs to the technical field of sulfuric acid process titanium dioxide production. By prolonging the first boiling time, canceling gray point observation, performing staged speed regulation stirring and optimizing the pressure maintaining and curing process, hydrolysis process parameters are optimized, and a staged calcination system adaptive to the characteristics of the hydrolysate is designed, so that the particle sizes of the hydrolysate are concentrated, the content of fine particles is low, and a titanium dioxide product with narrow particle size distribution, high whiteness, low yellowness and stable quality is finally obtained. The problems of wide particle size distribution, serious fine particle loss, large product quality fluctuation, over-burning / under-burning caused by mismatching of a hydrolysate and a calcination system and poor finished product performance in a traditional hydrolysis process are solved. The proportion of the hydrolysate with the particle size smaller than 1 micron is reduced by 0.5%, the hydrolysis rate is increased by 0.15%, the L value of the calcined finished product is larger than or equal to 95.5, the b value is smaller than or equal to 2.7, the daily output is increased to 15 batches, and remarkable economic and technical benefits are achieved.

Description

Technical Field

[0001] This invention relates to the field of sulfuric acid process titanium dioxide production technology, and in particular to a method for preparing hydrolyzed metatitanic acid with narrow particle size distribution and high-whiteness crude rutile. Background Technology

[0002] Hydrolysis and calcination are the two core processes in the production of titanium dioxide using the sulfuric acid process, and their compatibility directly determines the final product quality and production economics. An ideal production process must meet the following requirements: the hydrolysis products should have uniform particle size, concentrated distribution, and high hydrolysis rate; the calcination process should efficiently complete crystal transformation and impurity removal, while maintaining the narrow particle size characteristics of the hydrolysis products to avoid over-burning of fine particles or under-burning of coarse particles.

[0003] Existing technologies suffer from two major problems: First, traditional hydrolysis processes have significant drawbacks, such as reliance on manual judgment of the ash-turning point leading to quality fluctuations, the inability of uniform stirring to adapt to the needs of different reaction stages, the tendency to generate fine particles in the later stages causing material loss, and the difficulty in simultaneously achieving a high hydrolysis rate and particle size distribution. Second, traditional calcination regimes often use fixed parameters and are not designed to adapt to the characteristics of the hydrolysis products, resulting in a disconnect between hydrolysis and calcination. For example, when the proportion of fine particles in the hydrolysis products is high, the high temperature and long holding time of traditional calcination can easily cause over-burning and discoloration of the fine particles, increasing their yellowness (b-value). Furthermore, when the particle size distribution of the hydrolysis products is unstable, the particle size dispersion of the finished product after calcination further increases, affecting the performance of downstream applications. In addition, traditional processes have limited capacity, and the hydrolysis and calcination cycles are not coordinated, easily leading to material accumulation or equipment idleness.

[0004] Therefore, there is an urgent need to develop a method for synergistic optimization of hydrolysis and calcination. This method aims to obtain high-quality hydrolysis products by optimizing the hydrolysis process, and at the same time design a calcination regime that is adapted to the characteristics of the products, so as to achieve seamless integration of the two processes and ultimately obtain titanium dioxide products with narrow particle size distribution, high quality, and high production capacity. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for preparing hydrolyzed metatitanic acid with narrow particle size distribution and high-whiteness crude rutile.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention first proposes a method for preparing hydrolyzed metatitanic acid with a narrow particle size distribution and crude rutile with high whiteness, including a hydrolysis step and a calcination step, wherein the hydrolysis step and the calcination step are coordinated and adapted, and the specific steps are as follows:

[0008] S1. Hydrolysis process:

[0009] S1.1 First boil: Heat the seed-containing soluble titanium oxysulfate solution to boiling and maintain for 28-32 minutes with a stirring speed of 16-18 r / min. Extending the first boil time can ensure that the titanium solution is heated evenly and that the initial hydrolysis reaction proceeds uniformly. A higher stirring speed can prevent local overheating and avoid localized violent reactions that could lead to uneven particle size.

[0010] S1.2 First ripening: Stop heating and ripen steadily for 28-32 minutes, stirring at 7-8 r / min; a lower stirring speed can reduce collision and breakage between particles and promote the initial stable growth of particles.

[0011] S1.3, Second Boiling: Reheat to boiling and maintain for 18-22 minutes with a stirring speed of 10-12 r / min. At this speed, the reaction system can be uniformly mixed while avoiding damage to the generated particles caused by excessive stirring.

[0012] S1.4, Pressure holding and maturation: Under constant pressure, maintain pressure for 2 hours 20 minutes to 2 hours 40 minutes, and control the stirring speed in three stages: 10-12 r / min for the first hour, 7-8 r / min for the middle hour, and 4-6 r / min for the last 20-40 minutes; reduce the stirring speed in stages to adapt to the changes in hydrolysis rate and reduce the generation of fine particles; the constant pressure environment further ensures the stability of the reaction.

[0013] S1.5 Second ripening: Stop stirring and let it stand for 18-22 minutes to obtain hydrated titanium dioxide precipitate; after stopping stirring, the fine particles generated by incomplete hydrolysis will form larger particles through agglomeration, reducing material loss in the subsequent washing and calcination process, and making the hydrolysis reaction more complete.

[0014] The hydrolysis reaction principle is as follows: Under seeding and heating conditions, soluble titanium oxysulfate hydrolyzes to form a hydrated titanium dioxide precipitate that is insoluble in water. The reaction equation is: .

[0015] S1.6 Seed Crystal Addition: Add rutile seed crystals to the hydrated titanium dioxide precipitate at a rate of 3%-5%;

[0016] S2. Calcination process: The hydrated titanium dioxide precipitate is fed into a rotary kiln with an air velocity of 0.7-0.9 m / s and an oxidizing air atmosphere, and the following steps are performed sequentially:

[0017] S2.1 Preheating and drying section: The room temperature is raised to 250-300℃ at a rate of 6-8℃ / min, and the material retention time is 20-30min; free water is gently removed to avoid rapid evaporation of moisture that could cause particle breakage and to maintain the integrity of the particle structure.

[0018] S2.2 Crystallization and Dehydration Section: Heating to 390-410℃, heating rate 3-5℃ / min, material retention time 30-40min; removing water of crystallization ( This helps maintain the stability of the particle structure and prevents particles from agglomerating and clumping due to excessively rapid dehydration.

[0019] S2.3, Sulfate Decomposition Section: Heat to 640-660℃, heating rate 2-3℃ / min, material retention time 35-45min; fully decompose residual sulfate ions ( The process reduces impurity content and avoids sulfate residue that could increase the yellowness of the finished product; the generated SO2 is treated by a lime slurry absorption tower before being discharged in compliance with standards.

[0020] S2.4 Crystal Transformation Section: Heat to 840-860℃, heating rate 3-4℃ / min, material residence time 40-50min; promote the conversion of anatase to rutile (conversion rate ≥98%), rely on the advantage of uniform hydrolysis product particles to improve the synchronization of conversion and avoid quality fluctuations caused by insufficient local conversion.

[0021] S2.5 Crystal growth stage: Heat to 920-940℃, heating rate 2-3℃ / min, material residence time 20-30min; compared with the traditional calcination process, the peak temperature is reduced by 20-30℃ and the holding time is shortened by 10-15min, avoiding overheating and discoloration caused by fine particles due to their large specific surface area and fast heat conduction.

[0022] S2.6 Cooling Section: Cool from 920-940℃ to below 120℃ at a rate of 5-7℃ / min, hold for 25-35 minutes, and cool in air atmosphere to obtain high-whiteness rutile crude product. Rapid cooling avoids excessive crystal growth, prevents material moisture absorption, and maintains stable particle structure.

[0023] Preferably, in S1: the first boiling time is 30 min and the rotation speed is 17 r / min; the first maturation time is 30 min and the rotation speed is 7.5 r / min; the second boiling time is 20 min and the rotation speed is 11 r / min; the holding time is 2 h 30 min and the rotation speed is 5 r / min in the later stage; and the second maturation time is 20 min.

[0024] Preferably, in S2, the oxygen content of the oxidizing air atmosphere is 5%-8%.

[0025] Preferably, in step S2.3, the SO2 generated in the sulfate decomposition section is treated by a lime slurry absorption tower before being discharged.

[0026] Preferably, in S2.6, in S2, the material retention time is controlled by adjusting the rotary kiln operating speed and the length of each calcination section.

[0027] Preferably, the temperature difference in each calcination stage of S2 is controlled within ±5℃, and two temperature measuring points are set for each stage for real-time monitoring.

[0028] Preferably, the daily capacity of the four hydrolysis pots in the S1 hydrolysis process is 15 batches, and the daily processing capacity of the rotary kiln in the S2 calcination process matches the hydrolysis capacity.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. More concentrated and stable particle size distribution: Through optimization of the hydrolysis process, the D10 of the hydrolysis product increases by 0.11μm compared with the original process, and the proportion of <1μm particles decreases by 0.5%; combined with the appropriate calcination regime, the D50 of the finished product after calcination is stable at 2.1-2.2μm, and the proportion of <1μm particles is ≤13.5%. The narrow particle size distribution characteristic runs through the entire production process, perfectly matching the downstream crushing and coating processes.

[0031] 2. Significantly improved finished product quality: The elimination of the hydrolysis ash point observation process and the precise temperature control during calcination have avoided human error and over-burning issues. The whiteness (L value) of the finished product has increased from 95.31 in the traditional process to ≥95.5, the yellowness (b value) has decreased from 2.96 to ≤2.7, the crystal form conversion rate is ≥98%, and the residual sulfate is ≤0.05%. All indicators are better than the industry average.

[0032] 3. Improved material utilization and production capacity: The hydrolysis process promotes fine particle agglomeration by stopping stirring and maturation, reducing the solid titanium content in wastewater from 0.074 to 0.057 and reducing material loss; the calcination cycle is coordinated with the hydrolysis rhythm, increasing the daily production capacity from 14 batches to 15 batches, an increase of 7.1%, while the calcination energy consumption is reduced by 5-8% compared with the traditional process (due to the reduction of peak temperature and cycle optimization).

[0033] 4. Easier and more environmentally friendly operation: The hydrolysis process eliminates the need for manual observation of the ash turning point, and the calcination process uses PLC automatic temperature control, which reduces the difficulty of operation and the rate of human error; the SO2 generated in the sulfate decomposition section is absorbed and treated by lime milk, and the exhaust gas meets the emission standards, making it more environmentally friendly. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0035] Example 1:

[0036] The preparation method of hydrolyzed metatitanic acid with narrow particle size distribution and crude rutile with high whiteness is as follows:

[0037] S1. Hydrolysis process:

[0038] S1.1, First boil: The seeded titanium sulfate solution is introduced into the hydrolysis vessel, heated to boiling, maintained for 30 minutes, and stirred at 17 r / min.

[0039] S1.2 First ripening: Stop heating and let it ripen steadily for 30 minutes, stirring at 7.5 r / min;

[0040] S1.3, Second Boil: Reheat to boiling and maintain for 20 minutes, stirring at 11 r / min;

[0041] S1.4, Pressure holding and curing: Hold at constant pressure for 2 hours and 30 minutes, with a rotation speed of 11 r / min for the first hour, 7.5 r / min for the middle hour, and 5 r / min for the last 30 minutes;

[0042] S1.5 Second ripening: Stop stirring and let it stand for 20 minutes to obtain hydrated titanium dioxide precipitate;

[0043] S1.6 Seed Addition: Add rutile seed crystals to the hydrated titanium dioxide precipitate at a concentration of 4%.

[0044] S2, calcination process, wind speed 0.8 m / s, oxygen content of oxidizing air atmosphere is 8%:

[0045] S2.1 Preheating and drying section: room temperature → 300℃, heating rate 7℃ / min, residence time 25min;

[0046] S2.2 Crystallization and dehydration section: 180℃→400℃, heating rate 4℃ / min, residence time 35min;

[0047] S2.3, Sulfate decomposition section: 400℃→650℃, heating rate 2.5℃ / min, residence time 40min;

[0048] S2.4, Crystal transformation section: 650℃→850℃, heating rate 3.5℃ / min, residence time 45min;

[0049] S2.5, Crystal growth section: 850℃→930℃, heating rate 2.5℃ / min, hold for 25min;

[0050] S2.6 Cooling section: 930℃→110℃, cooling rate 6℃ / min, residence time 30min, cooling air temperature 25℃.

[0051] Example 2:

[0052] The preparation method of hydrolyzed metatitanic acid with narrow particle size distribution and crude rutile with high whiteness is as follows:

[0053] S1. Hydrolysis process:

[0054] S1.1, First boil: Maintain for 28 minutes, stirring speed 16 r / min;

[0055] S1.2, First maturation: Maintain for 28 minutes, stirring speed 7 r / min;

[0056] S1.3, Second Boil: Maintain for 18 minutes, stirring speed 10 r / min;

[0057] S1.4, Pressure holding and curing: Hold pressure for 2 hours and 20 minutes, with a rotation speed of 10 r / min for the first hour, 7 r / min for the middle hour, and 4 r / min for the last 20 minutes;

[0058] S1.5, Second maturation: Let it stand for 18 minutes to mature;

[0059] S1.6 Seed Addition: Rutile seed crystals were added to the hydrated titanium dioxide precipitate, with the amount of rutile seed crystals added being 43%.

[0060] S2. Calcination process:

[0061] S2.1 Preheating and drying section: 250℃, stay for 20 minutes;

[0062] S2.2 Crystallization and dehydration section: 390℃, stay for 30 min;

[0063] S2.3, Sulfate decomposition section: 640℃, hold for 35 min;

[0064] S2.4, Crystal transformation section: 840℃, stay for 40 min;

[0065] S2.5, Crystal growth section: 920℃, stay for 20 minutes;

[0066] S2.6 Cooling section: stay for 25 minutes.

[0067] Example 3:

[0068] The preparation method of hydrolyzed metatitanic acid with narrow particle size distribution and crude rutile with high whiteness is as follows:

[0069] S1. Hydrolysis process:

[0070] S1.1, First boil: Maintain for 32 minutes, stirring speed 18 r / min;

[0071] S1.2, First maturation: Maintain for 32 minutes, stirring speed 8 r / min;

[0072] S1.3, Second Boil: Maintain for 22 minutes, stirring speed 12 r / min;

[0073] S1.4, Pressure holding and curing: Hold pressure for 2 hours and 40 minutes, with a rotation speed of 12 r / min for the first hour, 8 r / min for the middle hour, and 6 r / min for the last 40 minutes;

[0074] S1.5, Second maturation: Let it stand for 22 minutes;

[0075] S1.6 Seed Addition: Add rutile seed crystals to the hydrated titanium dioxide precipitate at a concentration of 5%;

[0076] S2. Calcination process:

[0077] S2.1 Preheating and drying section: 275℃, stay for 30 minutes;

[0078] S2.2 Crystallization and dehydration section: 410℃, stay for 40 min;

[0079] S2.3, Sulfate decomposition section: 660℃, stay for 45 min;

[0080] S2.4, Crystal Transformation Section: 860℃, hold for 50 min;

[0081] S2.5, Crystal growth section: 940℃, stay for 30 min;

[0082] S2.6 Cooling section: stay for 35 minutes.

[0083] The following comparison model was also set:

[0084] Comparative Example 1: The stirring mode of the hydrolysis process was changed to a traditional fixed speed: 11 r / min was maintained throughout the process (the staged speed adjustment was canceled), and the other hydrolysis parameters (first boil 30 min, ash point canceled, pressure holding 2.5 h, stirring stop for 20 min) and calcination parameters were the same as those in Example 1.

[0085] Comparative Example 2: The hydrolysis process was restored to the traditional "observation of the ash point after boiling": 30 minutes after boiling, steam was passed through to observe the ash point (takes 25 minutes). The remaining hydrolysis parameters (staged speed adjustment, pressure holding for 2.5 hours, and 20 minutes of maturation after stirring) and calcination parameters were consistent with those of Example 1.

[0086] Comparative Example 3: Hydrolysis was stopped directly after 2.5 hours of pressure holding, and the "stop stirring and let stand for 20 minutes to mature" was cancelled. The remaining hydrolysis parameters (staged speed adjustment, cancellation of ash point) and calcination parameters were the same as those in Example 1.

[0087] Comparative Example 4: The peak temperature of the calcination crystal growth section was changed to the traditional 980℃ (stay for 35 min), and the remaining calcination parameters and hydrolysis parameters were the same as in Example 1.

[0088] Comparative Example 5: The calcination process was carried out with a uniform heating rate (5℃ / min), and the pauses at each stage were eliminated (the temperature was directly raised from room temperature to 930℃ and then cooled). The remaining calcination parameters (peak temperature 930℃, staged wind speed) and hydrolysis parameters were consistent with those of Example 1.

[0089] Comparative Example 6: The wind speed was fixed at 0.5 m / s throughout the calcination process (staged wind speed adjustment was canceled), and the remaining calcination parameters (staged heating and dwell time, peak temperature 930℃) and hydrolysis parameters were the same as in Example 1.

[0090] Performance testing: Crystal form conversion rate, particle size distribution (D10, D50, D90, percentage of <1μm), whiteness (L value), yellowness (b value), hydrolysis rate, solid titanium in wastewater, and dissolved titanium in wastewater were tested. The results are shown below:

[0091] Table 1. Detection results of products in each group

[0092]

[0093] Data Analysis:

[0094] From the perspective of particle size distribution, Examples 1-3 exhibit a significant advantage in narrow particle size distribution: D10 remains stable at 0.57-0.59 μm, with <1 μm particles accounting for only 13.66%-13.80%, and D50 fluctuates within ±0.03 μm, demonstrating the synergistic effect of staged adjustable-speed stirring and maturation with stirring stopped. In contrast, in Comparative Example 1 (uniform stirring), D10 decreased to 0.45 μm, and the proportion of <1 μm particles increased to 15.32%, with a significant increase in the number of fine particles, proving that staged speed adjustment can adapt to the reaction requirements of different hydrolysis stages and avoid particle unevenness caused by local overheating. In Comparative Example 3 (maturation without stirring stopped), the proportion of <1 μm particles reached 14.89%, and the titanium solids in the wastewater were 0.071, an increase of 24.6% compared to Example 1, confirming that stopping stirring can promote the aggregation of fine particles and reduce loss.

[0095] In terms of optical performance, Example 1 showed the best results with an L value of 95.62 and a b value of 2.68, followed closely by Examples 2-3 (L value ≥ 95.51, b value ≤ 2.72), with minimal fluctuations (L value ±0.08 to ±0.09). Comparative Example 2 (recovery of the graying point) exhibited an L value fluctuation of ±0.11 and a b value increase to 2.83 due to human error, resulting in a significant decrease in batch stability. Comparative Example 4 (high-temperature calcination), while showing a slightly higher crystal form conversion rate (98.7%), saw a surge in the b value to 3.05 and a decrease in whiteness to 95.28, highlighting the crucial role of "low-temperature short dwell time" in controlling over-burning of fine particles. The superior optical performance of these examples is a result of the synergistic effect of eliminating the graying point, precise temperature control during calcination, and narrow particle size distribution.

[0096] Data on hydrolysis efficiency and material loss show that the hydrolysis rate of all examples is ≥96.60%, slightly higher than that of Comparative Example 1 (96.41%) and Comparative Example 2 (96.52%), and the titanium solids in the wastewater are stable at 0.057-0.059, far lower than those of Comparative Example 3 (0.071) and Comparative Example 1 (0.068). It is noteworthy that the hydrolysis rate of the calcination-related comparative examples (4-6) is consistent with that of Example 1 (96.66%), indicating that hydrolysis parameters are the core factor affecting the hydrolysis rate, while calcination parameters mainly affect subsequent crystal transformation and performance optimization; the data are logically consistent.

[0097] Regarding the crystal form conversion rate, Examples 1-3 all achieved ≥98.2%, while Comparative Example 5 (without segmented residence time) only achieved 96.3%, a difference of 2.2 percentage points. This demonstrates that segmented residence times can ensure that sulfate decomposition and crystal form conversion occur simultaneously. Comparative Example 6 (fixed wind speed) achieved a conversion rate of 97.8%, slightly lower than the Examples, reflecting the optimization effect of the oxidizing atmosphere flow velocity on heat and mass transfer.

[0098] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing hydrolyzed metatitanic acid with narrow particle size distribution and crude rutile with high whiteness, characterized in that, The process includes a hydrolysis step and a calcination step, which are coordinated and adapted together. The specific steps are as follows: S1. Hydrolysis process: S1.1, First boil: Heat the seed-containing soluble titanium oxysulfate solution to boiling and maintain for 28-32 minutes, stirring at 16-18 r / min; S1.2 First ripening: Stop heating and ripen steadily for 28-32 minutes, stirring speed 7-8 r / min; S1.3, Second Boil: Reheat to boiling and maintain for 18-22 minutes, stirring at 10-12 r / min; S1.4, Pressure holding and maturation: Hold under constant pressure for 2 hours 20 minutes to 2 hours 40 minutes, and control the stirring speed in three stages: 10-12 r / min for the first hour, 7-8 r / min for the middle hour, and 4-6 r / min for the last 20-40 minutes; S1.5 Second ripening: Stop stirring and let it stand for 18-22 minutes to obtain hydrated titanium dioxide precipitate; S1.6 Seed Crystal Addition: Add rutile seed crystals to the hydrated titanium dioxide precipitate at a rate of 3%-5%; S2. Calcination process: The hydrated titanium dioxide precipitate is fed into a rotary kiln with an air velocity of 0.7-0.9 m / s and an oxidizing air atmosphere, and the following steps are performed sequentially: S2.1 Preheating and drying section: The room temperature is raised to 250-300℃, the heating rate is 6-8℃ / min, and the material retention time is 20-30min; S2.2 Crystallization and dehydration section: Heat to 390-410℃, heating rate 3-5℃ / min, material retention time 30-40min; S2.3, Sulfate decomposition section: Heat to 640-660℃, heating rate 2-3℃ / min, material retention time 35-45min; S2.4 Crystal transformation section: Heat to 840-860℃, heating rate 3-4℃ / min, material residence time 40-50min; S2.5 Crystal growth section: Heat to 920-940℃, heating rate 2-3℃ / min, material residence time 20-30min; S2.6 Cooling section: Cooling from 920-940℃ to below 120℃ at a rate of 5-7℃ / min, with a material retention time of 25-35min, to obtain high-whiteness rutile crude product.

2. The method for preparing narrow-particle-size hydrolyzed metatitanic acid and high-whiteness crude rutile according to claim 1, characterized in that, In S1: the first boiling time is 30 min and the rotation speed is 17 r / min; the first maturation time is 30 min and the rotation speed is 7.5 r / min; the second boiling time is 20 min and the rotation speed is 11 r / min; the holding time is 2 h 30 min and the rotation speed is 5 r / min in the later stage; the second maturation time is 20 min.

3. The method for preparing narrow-particle-size hydrolyzed metatitanic acid and high-whiteness crude rutile according to claim 1, characterized in that, In S2, the oxygen content of the oxidizing air atmosphere is 5%-8%.

4. The method for preparing narrow-particle-size hydrolyzed metatitanic acid and high-whiteness crude rutile according to claim 1, characterized in that, In S2.3, the SO2 generated in the sulfate decomposition section is treated by a lime slurry absorption tower before being discharged.

5. The method for preparing narrow-particle-size hydrolyzed metatitanic acid and high-whiteness crude rutile according to claim 1, characterized in that, In S2, the material retention time is controlled by adjusting the rotary kiln operating speed and the length of each calcination section.

6. The method for preparing narrow-particle-size hydrolyzed metatitanic acid and high-whiteness crude rutile according to claim 1, characterized in that, The temperature difference in each calcination stage of S2 is controlled within ±5℃, and two temperature measuring points are set up for each stage for real-time monitoring.

7. The method for preparing narrow-particle-size hydrolyzed metatitanic acid and high-whiteness crude rutile according to claim 1, characterized in that, The daily capacity of the four hydrolysis pots in the S1 hydrolysis process is 15 batches, and the daily processing capacity of the rotary kiln in the S2 calcination process matches the hydrolysis capacity.

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