Preparation process of high-activity anti-caking calcium hydroxide

Abstract

The application discloses a preparation process of high-activity anti-coagulation calcium hydroxide, and comprises the following steps: S1, calcining and crushing limestone into powder, and screening out impurities; S2, mixing and stirring the quicklime with anhydrous ethylene glycol and anhydrous ethanol into slurry; S3, feeding the slurry into a gradient digester, and performing digestion reaction by layer-by-layer water injection from top to bottom; and S4, filtering and drying the slurry after the digestion reaction. By forming the slurry of the quicklime and the anhydrous ethylene glycol, and then performing gradient reaction with water, the 'undercooked' problem caused by local overheating in the digestion reaction process is avoided, and the use of low-boiling-point ethanol further guarantees the high activity of the product.

Description

Technical Field

[0001] This invention relates to the field of calcium hydroxide production technology, and in particular to a preparation process for highly active, anti-coagulation calcium hydroxide. Background Technology

[0002] Calcium hydroxide, commonly known as slaked lime or quicklime, is produced by slaking quicklime with water. With the rapid development of industrial modernization and the increasing emphasis on environmental protection, calcium hydroxide has been widely used. Currently, the production process of calcium hydroxide is the traditional calcination, slaking, and impurity removal process. First, limestone is calcined at 900-1100℃ to obtain calcium oxide, which is then slaked with water to obtain calcium hydroxide. After impurity removal, drying, and pulverization, the product is obtained. During the slaking process, excessively high local temperatures can cause a layer of calcium hydroxide film to form more quickly on the surface of the originally dense sintered calcium oxide particles, hindering water penetration and resulting in "half-cooked" calcium hydroxide. Local overheating can also cause calcium hydroxide to recrystallize in the saturated slurry, leading to grain growth and reduced activity.

[0003] Patent 202511568042.X discloses a three-stage continuous quicklime digestion production process based on reaction process control. By setting up three digesters to carry out the reaction in steps, the problem caused by local overheating is reduced. However, the method has a spray device in the first digester. The droplets formed by the spray fall on the calcium oxide powder and form particles, which causes local small-scale overheating. It is difficult to quickly disperse the particles using the internal stirring device alone. At the same time, although the three digesters are integrated, the material in the previous digester can only be discharged into the next digester for processing after all the material in the previous digester has reached the set conditions. This makes continuous production impossible and results in low efficiency. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a preparation process for highly active anti-coagulation calcium hydroxide, so as to solve the problems of local overheating during the digestion of the prior art, resulting in the presence of calcium oxide cores and the inability to continuously and efficiently generate calcium hydroxide.

[0005] The objective of this invention is achieved through the following technical solution: a preparation process for highly active anti-coagulation calcium hydroxide, comprising the following steps, S1. Calcining and crushing limestone into powder, then sieving out impurities; S2. Mix quicklime with anhydrous ethylene glycol and anhydrous ethanol to form a slurry; S3. The slurry is fed into a gradient digester and water is injected layer by layer from top to bottom to carry out the digestion reaction; S4. Filter and dry the slurry after the digestion reaction.

[0006] Preferably, in step S3, the digestion reaction temperature is controlled at 85-150°C.

[0007] Preferably, the gradient digester includes a shell and a rotating shaft coaxially arranged inside the shell. The top of the shell has a feed inlet, and the bottom of the shell has a discharge outlet. Multiple digestion beds are arranged sequentially from top to bottom inside the shell. Each digestion bed includes a lower grinding disc, an upper grinding disc, and a collection hopper. The rotating shaft passes through the upper grinding disc and the lower grinding disc in sequence. The rotating shaft is fixedly connected to the lower grinding disc and drives it to rotate. The upper grinding disc has a material inlet and a liquid inlet. The collection hopper is sealed inside the shell and is located above the upper grinding disc. The bottom of the collection hopper has a discharge pipe for conveying material to the material inlet. The shell has a liquid inlet pipe for conveying water to the liquid inlet.

[0008] Preferably, the housing is provided with multiple exhaust ports, which are located between the hopper and the upper grinding disc.

[0009] Preferably, the injection port and the liquid injection port are eccentrically arranged, and the distance between the liquid injection port and the rotating shaft is less than the distance between the injection port and the rotating shaft.

[0010] Preferably, a fixing plate is fixedly provided on the inner wall of the housing, and a first limiting post is provided on the fixing plate. One end of the first limiting post is fixedly connected to the upper grinding disc, and the other end of the first limiting post passes through the fixing plate and is slidably connected to it. A first spring is fitted on the first limiting post.

[0011] Preferably, the lower grinding disc is provided with a retaining ring that intermittently blocks the material movement between the upper grinding disc and the lower grinding disc. The retaining ring is fitted outside the upper grinding disc and is slidably and sealingly connected to the upper grinding disc.

[0012] Preferably, the retaining ring is provided with a second limiting post, a second spring, and a baffle plate. The baffle plate is fixedly connected to the retaining ring. One end of the second limiting post is fixedly connected to the baffle plate, and the other end of the second limiting post passes through the fixing plate and is slidably connected to it. The second spring is fitted on the second limiting post and is located between the baffle plate and the fixing plate. A top rod is vertically fixed on the lower grinding disc, and an inclined block matching the top rod is fixed on the retaining ring.

[0013] Preferably, the housing is provided with a material collecting ring, which is fixed inside the housing. The material collecting ring is fitted outside the lower grinding disc and there is a material passage gap between them. The housing is provided with multiple air inlets, which are located between the upper and lower adjacent digestion beds.

[0014] The present invention has the following advantages: 1. This invention provides a process for preparing calcium hydroxide. By forming a slurry with quicklime and anhydrous ethylene glycol, and then carrying out a gradient reaction with water, the "half-cooked" problem caused by local overheating due to the addition of a large amount of water is avoided, allowing the reaction to proceed in an orderly and stable manner. At the same time, the low-boiling-point ethanol added during the reaction can guide the precipitation of calcium hydroxide, which helps to form a product with high porosity and large specific surface area, thereby improving the product activity. Moreover, the peristaltic effect of the airflow generated by ethanol evaporation can achieve a stirring effect on the material, and the large amount of steam generated can also hinder contact with carbon dioxide, avoiding deactivation by reaction with carbon dioxide, further improving the product activity. 2. The digestion reaction process of the present invention is carried out in a gradient reactor. The designed gradient reactor can form multiple digestion beds, which not only achieves the three effects of mixing, grinding and temperature control of materials in the digestion reaction process, but also enables continuous production of calcium hydroxide, thereby improving production efficiency. 3. Through the linkage between the retaining ring and the upper and lower grinding discs, the second spring, the push rod, and the inclined block, the digestion reaction is continuously carried out within the grinding gap formed by the upper and lower grinding discs, ensuring the temperature control and grinding effect of the digestion reaction. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the process flow of the present invention; Figure 2 This is a cross-sectional schematic diagram of the gradient digester of the present invention; Figure 3 yes Figure 2 A magnified schematic diagram of the partial structure at point A in the middle; Figure 4 This is a schematic diagram of a partial three-dimensional structure inside the gradient digester of the present invention.

[0016] In the diagram, 1. Shell; 2. Inlet; 3. Outlet; 4. Rotating shaft; 5. Digestion bed; 6. Lower grinding disc; 7. Upper grinding disc; 8. Injection port; 9. Liquid injection port; 10. Liquid injection pipe; 11. Collection hopper; 12. Discharge pipe; 13. Fixing plate; 14. First limiting post; 15. First spring; 16. Second limiting post; 17. Second spring; 18. Baffle plate; 19. Baffle ring; 20. Push rod; 21. Inclined block; 22. Collection ring; 23. Air inlet; 24. Exhaust port. Detailed Implementation

[0017] 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 only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0019] A preparation process for highly active anti-coagulation calcium hydroxide, such as... Figure 1 As shown, it includes the following steps: S1. After crushing the limestone into blocks, calcine it in a kiln at 900-1100℃, crush it into powder, and then screen out over-burned, under-burned blocks and impurities; S2. Mix quicklime with anhydrous ethylene glycol and anhydrous ethanol to form a slurry. The weight ratio of anhydrous ethylene glycol to quicklime is 5-8%, and the weight ratio of anhydrous ethanol to quicklime is 25-35%. Strictly control water to avoid premature digestion. The slurry is easy to transport later. S3. The slurry is fed into a gradient digester and water is injected layer by layer from top to bottom for digestion. The digestion reaction temperature is controlled at 85-150℃. The water ratio is gradually increased by injecting water layer by layer, so that the slurry reacts in stages. A large amount of heat is released during the digestion process. The temperature of the reaction is controlled so that the ethanol in the slurry reaches the boiling point and evaporates in large quantities. On the one hand, this can remove a large amount of heat and avoid local overheating. On the other hand, the ethanol vaporizes when heated and creates pores that escape, peeling off the calcium hydroxide shell covering the surface of calcium oxide. This achieves a stirring effect and promotes the reaction. At the same time, the large amount of ethanol volatilized can protect the calcium hydroxide and prevent it from contacting carbon dioxide and thus avoiding its deactivation. S4. After the digestion reaction, the slurry is filtered and dried, and the filtrate can be recycled for reuse.

[0020] The equipment used to control the reaction ratio is a gradient digester, such as... Figure 2 , Figure 3As shown, the gradient digester includes a shell 1, a rotating shaft 4 coaxially arranged inside the shell 1, and a motor located at the top of the shell 1. The motor drives the rotating shaft 4 to rotate. The top of the shell 1 has a feed inlet 2, and the bottom of the shell 1 has a discharge outlet 3. Multiple digestion beds 5 are arranged sequentially from top to bottom inside the shell 1. Each digestion bed 5 includes a lower grinding disc 6, an upper grinding disc 7, and a collection hopper 11. The rotating shaft 4 passes through the upper grinding disc 7 and the lower grinding disc 6 in sequence. The rotating shaft 4 is fixedly connected to the lower grinding disc 6 and drives it to rotate. There is a small gap between the rotating shaft 4 and the upper grinding disc 7. A fixing plate 13 is fixedly installed on the inner wall of the shell 1. The fixing plates 13 are symmetrically located inside the shell 1. Each fixed plate 13 is provided with a first limiting post 14. One end of the first limiting post 14 is fixedly connected to the top surface of the upper grinding disc 7, and the other end of the first limiting post 14 passes through the fixed plate 13 and slides up and down with it. A first spring 15 is fitted on the first limiting post 14. The first spring 15 pushes the upper grinding disc 7 to squeeze the lower grinding disc 6. The upper grinding disc 7 and the lower grinding disc 6 form a stationary grinding disc and a moving grinding disc, and a grinding surface is formed between the two. The rapidly rotating lower grinding disc 6 can centrifuge the material evenly outward. Water will expand after reacting with calcium oxide, and the first spring 15 will increase the grinding and mixing effect on the material.

[0021] The upper grinding disc 7 is provided with a feeding port 8 and a liquid injection port 9. The collecting hopper 11 is sealed inside the housing 1 and is located above the upper grinding disc 7. The bottom of the collecting hopper 11 is provided with a discharge pipe 12 for feeding material to the feeding port 8. The housing 1 is provided with a liquid injection pipe 10 for feeding water to the liquid injection port 9. Water for digestion reaction is introduced into the liquid injection pipe 10. The feeding port 8 and the liquid injection port 9 are eccentrically set. The distance of the liquid injection port 9 from the rotating shaft 4 is less than the distance of the feeding port 8 from the rotating shaft 4. Compared with the central feeding mixing, it can avoid the formation of dead zones. The eccentric setting of the feeding port 8 and the liquid injection port 9 can first form a water film, and then mix with the falling material to form a mixed thin layer for reaction, realizing the stirring and mixing of materials. The heat generated will also be quickly transferred to the upper grinding disc 7 and the lower grinding disc 6. Even if local thermal reaction forms particles, they will be ground and broken, so that the reaction can continue.

[0022] The rotating lower grinding disc 6 can generate centrifugal force to make the material between the grinding surfaces move outward quickly. However, if the speed is too fast, the material will detach from the grinding surface. The lower grinding disc 6 is provided with a baffle ring 19 that intermittently blocks the material movement between the upper grinding disc 7 and the lower grinding disc 6. The baffle ring 19 is fitted outside the upper grinding disc 7 and slides up and down to seal the upper grinding disc 7. When the baffle ring 19 moves downward, it blocks the channel for the material to move outward, causing the material to stay between the grinding surfaces and intercepting the reaction on the lower grinding disc 6. Then the baffle ring 19 moves upward to discharge the reacted material.

[0023] like Figure 4As shown, the retaining ring 19 is provided with a second limiting post 16, a second spring 17, and a baffle 18. The baffle 18 is fixedly connected to the retaining ring 19. One end of the second limiting post 16 is fixedly connected to the baffle 18, and the other end of the second limiting post 16 passes through the fixing plate 13 and slides up and down with it. The second spring 17 is fitted on the second limiting post 16 and is located between the baffle 18 and the fixing plate 13. A top rod 20 is vertically fixed on the lower grinding disc 6. An inclined block 21 matching the top rod 20 is fixed on the retaining ring 19. The cross-section of the inclined block 21 is a right triangle. The top rod 20 pushes the inclined surface of the inclined block 21, causing the retaining ring 19 to move upward.

[0024] like Figure 2 As shown, the shell 1 is provided with multiple exhaust ports 24, which are located between the hopper 11 and the upper grinding disc 7. The shell 1 is provided with a material collection ring 22, which is fixed inside the shell 1. The material collection ring 22 is fitted outside the lower grinding disc 6 and there is a material passage gap between them. The shell 1 is provided with multiple air inlets 23, which are located between the upper and lower adjacent digestion beds 5. The air inlets 23 are connected to external cold air. The airflow moves upward through the material passage gap, and after carrying away the heat on the upper grinding disc 7 and the lower grinding disc 6, it is discharged from the exhaust port 24.

[0025] Working principle: A mixed slurry of anhydrous ethylene glycol, anhydrous ethanol, and calcium oxide is conveyed from the feed inlet 2 to the collecting hopper 11 and enters the inlet 8 through the discharge pipe 12 at the bottom. The motor drives the rotating shaft 4 to rotate the lower grinding disc 6, which evenly disperses the material on the disc surface. Water is injected into the inlet 9 through the liquid injection pipe 10 to mix with the dispersed material and react with the grinding effect, so that the reaction continues. The rotating lower grinding disc 6 drives the top rod 20 to rotate. During the rotation, the inclined block 21 moves upward, which drives the retaining ring 19, the baffle plate 18, and the second limiting post 16 to move upward and squeeze the second spring 17, thus controlling the discharge of the ground material. The channel opens, and the material is thrown onto the collecting ring 22 and falls through the gap between it and the lower grinding disc 6 onto the collecting hopper 11 of the next layer. After the top rod 20 passes the inclined block 21, the second spring 17 resets and pushes the retaining ring 19 downward to block the discharge channel for grinding again. Water and calcium oxide undergo digestion reaction in the cavity formed by the grinding surface. The heat released between the grinding surfaces vaporizes the ethanol. Combined with the grinding effect of the grinding surface, the material is fully activated and the reaction is complete. The retaining ring 19 moves upward again, and the ethanol vapor escapes and is discharged from the exhaust port 24. The digestion reaction continues throughout the process. The gradient reaction achieves precise temperature control and ensures the high activity of the product.

[0026] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A preparation process for highly active anti-coagulation calcium hydroxide, characterized in that, Includes the following steps, S1. Calcining and crushing limestone into powder, then sieving out impurities; S2. Mix quicklime with anhydrous ethylene glycol and anhydrous ethanol to form a slurry; S3. The slurry is fed into a gradient digester and water is injected layer by layer from top to bottom to carry out the digestion reaction; S4. Filter and dry the slurry after the digestion reaction.

2. The preparation process of highly active anti-coagulation calcium hydroxide according to claim 1, characterized in that, In step S3, the digestion reaction temperature is controlled at 85-150℃.

3. The preparation process of highly active anti-coagulation calcium hydroxide according to claim 1, characterized in that: The gradient digester includes a shell (1) and a rotating shaft (4) coaxially arranged inside the shell (1). The top of the shell (1) is provided with a feed inlet (2) and the bottom of the shell (1) is provided with a discharge outlet (3). Multiple digestion beds (5) are arranged sequentially from top to bottom inside the shell (1). Each digestion bed (5) includes a lower grinding disc (6), an upper grinding disc (7), and a collection hopper (11). The rotating shaft (4) passes through the upper grinding disc (7) and the lower grinding disc (6) in sequence. The rotating shaft (4) is fixedly connected to the lower grinding disc (6) and drives it to rotate. The upper grinding disc (7) is provided with a material inlet (8) and a liquid inlet (9). The material collection hopper (11) is sealed inside the housing (1). The material collection hopper (11) is located above the upper grinding disc (7). The bottom of the material collection hopper (11) is provided with a material discharge pipe (12) for conveying material to the material inlet (8). The housing (1) is provided with a liquid inlet pipe (10) for conveying water to the liquid inlet (9).

4. The preparation process of highly active anti-coagulation calcium hydroxide according to claim 3, characterized in that: The housing (1) is provided with a plurality of exhaust ports (24), which are located between the hopper (11) and the upper grinding disc (7).

5. The preparation process of highly active anti-coagulation calcium hydroxide according to claim 3, characterized in that: The injection port (8) and the liquid injection port (9) are eccentrically arranged, and the distance of the liquid injection port (9) from the rotating shaft (4) is less than the distance of the injection port (8) from the rotating shaft (4).

6. The preparation process of highly active anti-coagulation calcium hydroxide according to claim 4, characterized in that: The inner wall of the housing (1) is fixedly provided with a fixing plate (13), and a first limiting post (14) is provided on the fixing plate (13). One end of the first limiting post (14) is fixedly connected to the upper grinding disc (7), and the other end of the first limiting post (14) passes through the fixing plate (13) and slides up and down with it. A first spring (15) is fitted on the first limiting post (14).

7. The preparation process of highly active anti-coagulation calcium hydroxide according to claim 6, characterized in that: The lower grinding disc (6) is provided with a retaining ring (19) that intermittently blocks the material movement between the upper grinding disc (7) and the lower grinding disc (6). The retaining ring (19) is fitted outside the upper grinding disc (7) and the retaining ring (19) slides up and down to seal the upper grinding disc (7).

8. The preparation process of highly active anti-coagulation calcium hydroxide according to claim 7, characterized in that: The retaining ring (19) is provided with a second limiting post (16), a second spring (17), and a baffle (18). The baffle (18) is fixedly connected to the retaining ring (19). One end of the second limiting post (16) is fixedly connected to the baffle (18). The other end of the second limiting post (16) passes through the fixing plate (13) and slides up and down with it. The second spring (17) is fitted on the second limiting post (16) and is located between the baffle (18) and the fixing plate (13). A top rod (20) is vertically fixed on the lower grinding disc (6). An inclined block (21) matching the top rod (20) is fixed on the retaining ring (19).

9. The preparation process of highly active anti-coagulation calcium hydroxide according to claim 1, characterized in that: The housing (1) is provided with a material collection ring (22), which is fixed inside the housing (1). The material collection ring (22) is fitted outside the lower grinding disc (6) and there is a material passage gap between them. The housing (1) is provided with multiple air inlets (23), which are located between the upper and lower adjacent digestion beds (5).

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