Process for producing nano calcium carbonate powder

Abstract

The application provides a production process of nano calcium carbonate powder and relates to the technical field of calcium carbonate, and comprises the following steps: S1: raw lime and hot soft water are introduced into a clarifying machine, heated and mixed, and slag is discharged to obtain coarse slurry which is stored in a coarse slurry tank; S2: the coarse slurry is introduced into a hydrocyclone to separate out slag which is discharged, the slurry is discharged into a fine slurry tank, refrigerated and introduced into a crystal guide agent to obtain fine slurry; S3: the fine slurry is introduced into a three-tower for three-step rectification, and carbon dioxide is synchronously introduced, and two-step coarse slurry tank refrigeration is carried out; in the application, the clean water generated in the whole production process is discharged into the production line of light calcium carbonate, and the light calcium carbonate is jointly produced to recycle and purify the clean water; the discharged slag is washed, combined with clay and the like to form a brick blank, the brick blank is aged through three-tower tail gas to obtain finished bricks, the waste slag is recycled and utilized by jointly producing the bricks, and the carbonization tail gas is recycled by utilizing the brick embryo aging process, so that the nano calcium carbonate production is zero-pollution, zero-emission and more environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of calcium carbonate technology, and in particular to a production process for nano-calcium carbonate powder. Background Technology

[0002] Nano-calcium carbonate is a novel ultra-fine solid powder material developed in the 1980s. Its particle size distribution is between 0.01 and 0.1 μm. Due to the ultra-optimization of nano-calcium carbonate particles, its molecular structure and surface electronic structure are altered, forming quantum technology size effect, small size effect, surface effect and macroeconomic quantum effect that are not present in ordinary calcium bicarbonate. It is widely used in plastics, papermaking industry, building materials, inks, architectural coatings, sealants and adhesives and other fields.

[0003] The key process for manufacturing nano-calcium carbonate involves carbonation, including intermittent carbonation, continuous spray carbonation, and high-gravity carbonation. Carbonation is currently the most widely used industrial method for preparing nano-calcium carbonate, allowing for good control over the particle size, distribution, morphology, and dispersibility of calcium carbonate. However, the preparation process of nano-calcium carbonate is complex, and its production inevitably generates dust and "three wastes" pollution, specifically waste gas, waste residue, and wastewater. How to reduce or achieve zero emissions is a key issue that needs to be addressed for the development of the nano-calcium carbonate industry. Therefore, this invention proposes a production process for nano-calcium carbonate powder to solve the problems existing in the prior art. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a production process for nano-calcium carbonate powder. This process achieves zero pollution and zero emissions in the production of nano-calcium carbonate, making it more environmentally friendly.

[0005] To achieve the objectives of this invention, the invention is implemented through the following technical solution: a production process for nano-calcium carbonate powder, comprising the following steps:

[0006] S1: Quicklime and hot soft water are passed into the cleaning machine for heating and mixing. The residue is discharged and the coarse slurry is stored in the coarse slurry tank.

[0007] S2: The coarse slurry is fed into a hydrocyclone separator to separate the slag and discharge it. The slurry is then discharged into a fine slurry tank for cooling and a crystallizing agent is introduced to obtain a fine slurry.

[0008] S3: The refined slurry is fed into the three towers for three-step distillation, with carbon dioxide being introduced simultaneously. After passing through two-step raw slurry tanks for cooling, it finally reaches the cooked slurry tank. The clear water is discharged, the cooked slurry is discharged into the activation tank, and the tail gas from the three towers is discharged.

[0009] S4: Activate the tank by introducing activator, then discharge it into the aging tank for aging, and then discharge it into the filter to separate it into filtrate and filtrate.

[0010] S5: the filtrate is introduced into a sedimentation tank, the precipitate and the clean water are separated, the clean water is discharged, the filter cake and the precipitate are introduced into a dryer to be dried into solids, and the solids are discharged into a pulverizer to be pulverized;

[0011] S6: the pulverized material is discharged into a cyclone separator to be separated to obtain nano calcium carbonate;

[0012] S7: the discharged residue is introduced into a residue washing tank to be washed with water, the residue washing water is discharged, then the residue is mixed with clay and purified waste water to be made into green bricks, the tail gas discharged from the three towers is used to age the green bricks, and finished bricks are obtained;

[0013] S8: the discharged clean water is introduced into a light calcium carbonate production line to react with quicklime, and the residue washing water is introduced into a purifier as raw material for a second reaction.

[0014] Further improvement lies in that, in S1, steam is generated during the heating and mixing reaction, and the steam is discharged into a heat exchanger to recover heat in the steam.

[0015] Further improvement lies in that, in S2, the crystal directing agent is an organic base or a crystal seed, and after the slurry is discharged into a fine slurry tank and introduced into the crystal directing agent, stirring is performed by stirring blades, the stirring speed is controlled to be 300-600 r / min, and the stirring is performed for 60-120 min.

[0016] Further improvement lies in that, S3 comprises the following steps:

[0017] S31: the fine slurry is introduced into a pre-tower for first rectification, carbon dioxide is introduced synchronously, and the discharged slurry is discharged to a first-step green slurry tank for refrigeration treatment;

[0018] S32: the gas discharged from the pre-tower is discharged into a middle tower, the discharged slurry in the first-step green slurry tank is introduced into the middle tower for second rectification, and then the discharged slurry is discharged to a second-step green slurry tank for refrigeration treatment;

[0019] S33: the gas discharged from the middle tower is discharged into a post-tower, the discharged slurry in the second-step green slurry tank is introduced into the post-tower for third rectification, and then the discharged slurry is introduced into a mature slurry tank to obtain mature slurry;

[0020] S34: the clean water in the mature slurry tank is discharged, and the tail gas of the post-tower is discharged.

[0021] Further improvement lies in that, in S4, the preparation process of the activating agent is as follows: the following components are selected as raw materials according to a mass ratio: 25-35 parts of NaOH solution, 30-40 parts of C17H35COOH, 3-10 parts of sodium castor oil sulfonate, and 50-100 parts of water, the above raw materials are mixed and stirred at 60-70 ℃ for 50-70 min, and the stirring speed is controlled to be 200-250 r / min to obtain the activating agent.

[0022] Further improvement lies in that in the S4, the activator is introduced into the activation tank and stirred by the stirring blade, the stirring speed is controlled to be 400-600r / min, the stirring time is 10-15min, the temperature is controlled to be normal temperature during aging, and the aging time is controlled to be within 1 day.

[0023] Further improvement lies in that in the S5, after the filtrate is introduced into the precipitation tank, the precipitation is performed for 1-2h until the filtrate is obviously layered, the upper clear water is overflowed and discharged, the lower precipitate is collected into the dryer, and the filter cake is introduced synchronously for mixing and synchronous drying, and the temperature is controlled to be 80-90 DEG C during drying to dry the moisture.

[0024] Further improvement lies in that in the S6, the tail gas discharged from the cyclone separator is introduced into the bag-type dust collector for dust removal, and the particles in the bag-type dust collector are collected after being discharged to the outside.

[0025] Further improvement lies in that in the S7, the purified wastewater is selected from various residual wastewaters in the whole process, the wastewater is treated by flocculation, filtration and sterilization and odor removal for secondary utilization, and the tail gas is discharged to the filtering and adsorbing equipment for purification treatment after the brick billet is aged, and then is discharged to the outside.

[0026] Further improvement lies in that in the S8, all the discharged clear water and washing residue water are collected into different water tanks, and the temperature is adjusted according to actual needs.

[0027] The beneficial effects of the present application are as follows:

[0028] 1. In the present application, the clear water generated in the whole production process is discharged into the production line of light calcium carbonate, and is produced in combination with the light calcium carbonate to recycle and purify the clear water, the discharged residue water is washed, and is combined with clay to form a brick billet, and the finished product brick is obtained by aging through the three-tower tail gas, and the waste residue is recycled and utilized by being combined with the brick production, and the carbonization tail gas is recycled by utilizing the brick billet aging process, so that the production of nano calcium carbonate is zero pollution and zero emission, and is more environmentally friendly.

[0029] 2. In the present application, the refined pulp is introduced into the pre-tower for primary rectification, and carbon dioxide is introduced synchronously, the discharged pulp is discharged to the first-step raw pulp tank for refrigeration treatment, the gas discharged from the pre-tower is discharged into the middle tower, the discharged pulp in the first-step raw pulp tank is discharged into the middle tower for secondary rectification, the discharged pulp is discharged to the second-step raw pulp tank for refrigeration treatment, the gas discharged from the middle tower is discharged into the rear tower, the discharged pulp in the second-step raw pulp tank is discharged into the rear tower for third rectification, and the discharged pulp is discharged to the mature pulp tank to obtain mature pulp, and in the whole process, continuous bubbling carbonization is adopted to improve the utilization rate of carbon dioxide.

[0030] 3、The present application produces nano calcium carbonate through carbonization reaction, the raw material source is extensive, the cost is low, greatly reduces the production cost of nano calcium carbonate, and a large amount of nano calcium carbonate can be produced, effectively improving the efficiency and yield of nano calcium carbonate. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The flow chart of the present application. DETAILED DESCRIPTION

[0032] In order to deepen the understanding of the present application, the present application will be further described in combination with examples, and the present examples are only used to explain the present application, and do not constitute the limitation to the protection scope of the present application.

[0033] Example one

[0034] According to Figure 1 As shown in the figure, the present embodiment proposes a production process of nano calcium carbonate powder, including the following steps:

[0035] The quicklime and hot soft water are introduced into the cleaning machine for heating and mixing, and the slag is discharged to obtain the coarse slurry stored in the coarse slurry tank; in the process of heating and mixing reaction, steam is generated, and the heat in the steam is discharged into the heat exchanger to recover the heat in the steam;

[0036] The coarse slurry is introduced into the hydrocyclone to separate the slag and discharge, and the slurry is discharged into the fine slurry tank for refrigeration and introduced into the crystal guide agent to obtain the fine slurry; the crystal guide agent is organic alkali or crystal seed, and after the slurry is discharged into the fine slurry tank and introduced into the crystal guide agent, stirring is carried out by the stirring blade, and the stirring speed is controlled at 500r / min, and the stirring time is 100min;

[0037] The fine slurry is introduced into the three towers for three-step rectification, and carbon dioxide is introduced synchronously, and after two-step slurry tank refrigeration, the final slurry tank, the clear water is discharged, and the slurry is discharged into the activation tank, and the tail gas of the three towers is discharged; specifically including the following steps: the fine slurry is introduced into the pre-tower for one-step rectification, and carbon dioxide is introduced synchronously, and the slurry is discharged to the first-step slurry tank for refrigeration treatment; the gas discharged from the pre-tower is discharged into the middle tower, and the slurry discharged from the first-step slurry tank is discharged into the middle tower for two-step rectification, and then the slurry is discharged to the second-step slurry tank for refrigeration treatment; the gas discharged from the middle tower is discharged into the rear tower, and the slurry discharged from the second-step slurry tank is discharged into the rear tower for three-step rectification, and then discharged into the slurry tank to obtain the slurry; the clear water in the slurry tank is discharged, and the tail gas of the rear tower is discharged;

[0038] An activator is introduced into the activation tank for activation, followed by aging in an aging tank, and then filtered to separate the liquid and paste. The preparation process of the activator is as follows: the following components are selected as raw materials according to the mass ratio: 25 parts NaOH solution, 30 parts C17H35COOH, 3 parts sodium castor oil sulfonate, and 50 parts water. The above raw materials are mixed and stirred at 65°C for 60 minutes, with the stirring speed controlled at 220 r / min, to obtain the activator. The activator is introduced into the activation tank and stirred by the stirring blades at a stirring speed controlled at 500 r / min for 12 minutes. During aging, the temperature is controlled at room temperature, and the aging time is controlled within 1 day.

[0039] The filtrate is passed into a sedimentation tank to separate the precipitate and clear water. The clear water is discharged, and the filter paste and precipitate are passed into a dryer to dry into a solid. The solid is then discharged into a pulverizer for pulverization. Specifically, after the filtrate is passed into the sedimentation tank, it is allowed to settle for 1.5 hours until the filtrate clearly separates into layers. The upper clear water overflows and is discharged, while the lower precipitate is collected and passed into a dryer. Filter paste is simultaneously introduced and mixed for simultaneous drying. During the drying process, the temperature is controlled at 85℃ to remove moisture.

[0040] The pulverized material is fed into a cyclone separator to separate and obtain nano-calcium carbonate; the exhaust gas from the cyclone separator is passed into a bag filter for dust removal, and after dust removal, it is discharged to the outside, collecting the particles in the bag filter.

[0041] The slag discharged above is fed into a slag washing tank for washing, and the washing water is discharged. Then, the slag is mixed with clay and purified wastewater to make brick blanks. The brick blanks are aged using the exhaust gas discharged from the three towers to obtain finished bricks. The purified wastewater is selected from various residual sewages in the entire process. These sewages are treated by flocculation, filtration, sterilization and deodorization for reuse. The exhaust gas is used to age the brick blanks, and then the exhaust gas is discharged to a filtration and adsorption device for purification before being discharged to the outside. The discharged slag is washed with water, mixed with clay, etc. to make brick blanks, and aged using the exhaust gas from the three towers to obtain finished bricks. This process is combined with brick making to recycle waste slag and to recycle carbonization exhaust gas during the brick blank aging process.

[0042] The discharged water is fed into the light calcium carbonate production line to react with quicklime, and the slag washing water is fed into a purification machine as raw material for a second reaction. All discharged water and slag washing water are collected in separate tanks and heated and regulated according to actual needs. The water generated in the entire production process is discharged into the light calcium carbonate production line to be recycled and purified in conjunction with the light calcium carbonate production.

[0043] Example 2

[0044] according to Figure 1 As shown in the figure, this embodiment proposes a production process for nano-calcium carbonate powder, including the following steps:

[0045] Quicklime and hot soft water are fed into a cleaning machine for heating and mixing. The residue is discharged, and the resulting coarse slurry is stored in a coarse slurry tank. During the heating and mixing reaction, steam is generated and discharged into a heat exchanger to recover the heat from the steam.

[0046] The coarse slurry is fed into a hydrocyclone separator to separate the slag and discharge it. The slurry is then discharged into a fine slurry tank for cooling and a crystal guide agent is introduced to obtain a fine slurry. The crystal guide agent is an organic alkali or a seed crystal. After the slurry is discharged into the fine slurry tank and the crystal guide agent is introduced, it is stirred by a stirring blade. The stirring speed is controlled at 500 r / min and the stirring time is 100 min.

[0047] The refined slurry is fed into a three-stage distillation tower for three-step rectification, with carbon dioxide introduced simultaneously. After passing through two stages of raw slurry tanks for cooling, it finally reaches the cooked slurry tank, where the water is discharged. The cooked slurry is then discharged into an activation tank, and the tail gas from the three towers is discharged. Specifically, the steps include: the refined slurry is fed into a pre-tower for primary rectification, with carbon dioxide introduced simultaneously, and the slurry discharged is sent to the first-stage raw slurry tank for cooling; the gas discharged from the pre-tower is discharged into the intermediate tower, and the slurry discharged from the first-stage raw slurry tank is sent into the intermediate tower for secondary rectification, then the slurry is sent to the second-stage raw slurry tank for cooling; the gas discharged from the intermediate tower is sent into the final tower, and the slurry discharged from the second-stage raw slurry tank is sent into the final tower for tertiary rectification, then the slurry is sent to the cooked slurry tank to obtain cooked slurry; the water in the cooked slurry tank is discharged, and the tail gas from the final tower is discharged.

[0048] An activator is introduced into the activation tank for activation, followed by aging in an aging tank, and then filtered to separate the liquid and filtrate. The preparation process of the activator is as follows: the following components are selected as raw materials according to the mass ratio: 30 parts NaOH solution, 35 parts C17H35COOH, 5 parts sodium castor oil sulfonate, and 80 parts water. The above raw materials are mixed and stirred at 65°C for 60 minutes, with the speed controlled at 220 r / min, to obtain the activator. The activator is introduced into the activation tank and stirred by the stirring blades at a speed controlled at 500 r / min for 12 minutes. During aging, the temperature is controlled at room temperature, and the aging time is controlled within 1 day.

[0049] The filtrate is passed into a sedimentation tank to separate the precipitate and clear water. The clear water is discharged, and the filter paste and precipitate are passed into a dryer to dry into a solid. The solid is then discharged into a pulverizer for pulverization. Specifically, after the filtrate is passed into the sedimentation tank, it is allowed to settle for 1.5 hours until the filtrate clearly separates into layers. The upper clear water overflows and is discharged, while the lower precipitate is collected and passed into a dryer. Filter paste is simultaneously introduced and mixed for simultaneous drying. During the drying process, the temperature is controlled at 85℃ to remove moisture.

[0050] The pulverized material is fed into a cyclone separator to separate and obtain nano-calcium carbonate; the exhaust gas from the cyclone separator is passed into a bag filter for dust removal, and after dust removal, it is discharged to the outside, collecting the particles in the bag filter.

[0051] The slag discharged above is fed into a slag washing tank for washing, and the washing water is discharged. Then, the slag is mixed with clay and purified wastewater to make brick blanks. The brick blanks are aged using the exhaust gas discharged from the three towers to obtain finished bricks. The purified wastewater is selected from various residual sewages in the entire process. These sewages are treated by flocculation, filtration, sterilization and deodorization for reuse. The exhaust gas is used to age the brick blanks, and then the exhaust gas is discharged to a filtration and adsorption device for purification before being discharged to the outside. The discharged slag is washed with water, mixed with clay, etc. to make brick blanks, and aged using the exhaust gas from the three towers to obtain finished bricks. This process is combined with brick making to recycle waste slag and to recycle carbonization exhaust gas during the brick blank aging process.

[0052] The discharged water is fed into the light calcium carbonate production line to react with quicklime, and the slag washing water is fed into a purification machine as raw material for a second reaction. All discharged water and slag washing water are collected in separate tanks and heated and regulated according to actual needs. The water generated in the entire production process is discharged into the light calcium carbonate production line to be recycled and purified in conjunction with the light calcium carbonate production.

[0053] Example 3

[0054] according to Figure 1 As shown in the figure, this embodiment proposes a production process for nano-calcium carbonate powder, including the following steps:

[0055] Quicklime and hot soft water are fed into a cleaning machine for heating and mixing. The residue is discharged, and the resulting coarse slurry is stored in a coarse slurry tank. During the heating and mixing reaction, steam is generated and discharged into a heat exchanger to recover the heat from the steam.

[0056] The coarse slurry is fed into a hydrocyclone separator to separate the slag and discharge it. The slurry is then discharged into a fine slurry tank for cooling and a crystal guide agent is introduced to obtain a fine slurry. The crystal guide agent is an organic alkali or a seed crystal. After the slurry is discharged into the fine slurry tank and the crystal guide agent is introduced, it is stirred by a stirring blade. The stirring speed is controlled at 500 r / min and the stirring time is 100 min.

[0057] The refined slurry is fed into a three-stage distillation tower for three-step rectification, with carbon dioxide introduced simultaneously. After passing through two stages of raw slurry tanks for cooling, it finally reaches the cooked slurry tank, where the water is discharged. The cooked slurry is then discharged into an activation tank, and the tail gas from the three towers is discharged. Specifically, the steps include: the refined slurry is fed into a pre-tower for primary rectification, with carbon dioxide introduced simultaneously, and the slurry discharged is sent to the first-stage raw slurry tank for cooling; the gas discharged from the pre-tower is discharged into the intermediate tower, and the slurry discharged from the first-stage raw slurry tank is sent into the intermediate tower for secondary rectification, then the slurry is sent to the second-stage raw slurry tank for cooling; the gas discharged from the intermediate tower is sent into the final tower, and the slurry discharged from the second-stage raw slurry tank is sent into the final tower for tertiary rectification, then the slurry is sent to the cooked slurry tank to obtain cooked slurry; the water in the cooked slurry tank is discharged, and the tail gas from the final tower is discharged.

[0058] An activator is introduced into the activation tank for activation, followed by aging in an aging tank, and then filtered to separate the liquid and paste. The preparation process of the activator is as follows: the following components are selected as raw materials according to the mass ratio: 35 parts NaOH solution, 40 parts C17H35COOH, 10 parts sodium castor oil sulfonate, and 100 parts water. The above raw materials are mixed and stirred at 65°C for 60 minutes, with the speed controlled at 220 r / min, to obtain the activator. The activator is introduced into the activation tank and stirred by the stirring blades at a speed controlled at 500 r / min for 12 minutes. During aging, the temperature is controlled at room temperature, and the aging time is controlled within 1 day.

[0059] The filtrate is passed into a sedimentation tank to separate the precipitate and clear water. The clear water is discharged, and the filter paste and precipitate are passed into a dryer to dry into a solid. The solid is then discharged into a pulverizer for pulverization. Specifically, after the filtrate is passed into the sedimentation tank, it is allowed to settle for 1.5 hours until the filtrate clearly separates into layers. The upper clear water overflows and is discharged, while the lower precipitate is collected and passed into a dryer. Filter paste is simultaneously introduced and mixed for simultaneous drying. During the drying process, the temperature is controlled at 85℃ to remove moisture.

[0060] The pulverized material is fed into a cyclone separator to separate and obtain nano-calcium carbonate; the exhaust gas from the cyclone separator is passed into a bag filter for dust removal, and after dust removal, it is discharged to the outside, collecting the particles in the bag filter.

[0061] The slag discharged above is fed into a slag washing tank for washing, and the washing water is discharged. Then, the slag is mixed with clay and purified wastewater to make brick blanks. The brick blanks are aged using the exhaust gas discharged from the three towers to obtain finished bricks. The purified wastewater is selected from various residual sewages in the entire process. These sewages are treated by flocculation, filtration, sterilization and deodorization for reuse. The exhaust gas is used to age the brick blanks, and then the exhaust gas is discharged to a filtration and adsorption device for purification before being discharged to the outside. The discharged slag is washed with water, mixed with clay, etc. to make brick blanks, and aged using the exhaust gas from the three towers to obtain finished bricks. This process is combined with brick making to recycle waste slag and to recycle carbonization exhaust gas during the brick blank aging process.

[0062] The discharged water is fed into the light calcium carbonate production line to react with quicklime, and the slag washing water is fed into a purification machine as raw material for a second reaction. All discharged water and slag washing water are collected in separate tanks and heated and regulated according to actual needs. The water generated in the entire production process is discharged into the light calcium carbonate production line to be recycled and purified in conjunction with the light calcium carbonate production.

[0063] Based on Examples 1, 2, and 3, it can be concluded that the activator prepared by the following mass ratio of the present invention—25-35 parts NaOH solution, 30-40 parts C17H35COOH, 3-10 parts sodium castor oil sulfonate, and 50-100 parts water—has a better activation effect on cooked pulp.

[0064] Particle size Content Moisture Bulk density Oil absorption value PH value Example 1 10-100 nm 96％ 0.1％ 0.45 g / ml 25 g / 100 g 9.6 Example 2 10-100 nm 98％ 0.1％ 0.43 g / ml 26 g / 100 g 9.8 Example 3 10-100 nm 97％ 0.1％ 0.46 g / ml 23 g / 100 g 9.7

[0065] The production process of this nano-calcium carbonate powder involves discharging the clean water generated during the entire production process into the production line of light calcium carbonate, where it is produced in conjunction with light calcium carbonate to recycle and purify the clean water. The discharged slag is washed and then mixed with clay to form brick blanks. The finished bricks are then aged using the tail gas from a three-tower process. This joint production with brick making recycles waste residue, and the aging process of the brick blanks is used to recycle carbonation tail gas, thus achieving zero pollution and zero emissions in the production of nano-calcium carbonate, making it more environmentally friendly. Simultaneously, this invention introduces a pre-tower for primary distillation, simultaneously introducing carbon dioxide. The discharged slurry is sent to the first-stage raw slurry tank for refrigeration. The gas discharged from the pre-tower is sent to the middle tower. The discharged slurry from the first-stage raw slurry tank is sent to the middle tower for secondary distillation. The discharged slurry is then sent to the second-stage raw slurry tank for refrigeration. The gas discharged from the middle tower is sent to the final tower. The discharged slurry from the second-stage raw slurry tank is sent to the final tower for tertiary distillation. The discharged slurry is then sent to the cooked slurry tank to obtain cooked slurry. Throughout the entire process, continuous bubbling carbonation is used to improve carbon dioxide utilization. In addition, this invention produces nano-calcium carbonate through a carbonation reaction. The raw materials are widely available and inexpensive, which greatly reduces the production cost of nano-calcium carbonate. Moreover, it can produce a large amount of nano-calcium carbonate, effectively improving the efficiency and yield of nano-calcium carbonate.

[0066] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A production process for nano-calcium carbonate powder, characterized in that, Includes the following steps: S1: Quicklime and hot soft water are passed into the cleaning machine for heating and mixing. The residue is discharged and the coarse slurry is stored in the coarse slurry tank. S2: The coarse slurry is fed into a hydrocyclone separator to separate the slag and discharge it. The slurry is then discharged into a fine slurry tank for cooling and a crystal guide agent is introduced to obtain a fine slurry. The crystal guide agent is an organic alkali or a seed crystal. S3: The refined slurry is fed into a three-stage distillation tower for three-step rectification, with carbon dioxide introduced simultaneously. After passing through two stages of raw slurry tanks for cooling, it finally reaches the cooked slurry tank. The purified water is discharged, and the cooked slurry is discharged into the activation tank. The tail gas from the three towers is discharged. Specifically, the following steps are included: The refined slurry is fed into the pre-tower for primary rectification, with carbon dioxide introduced simultaneously. The slurry discharged from the pre-tower is sent to the first-stage raw slurry tank for cooling treatment. The gas discharged from the pre-tower is discharged into the middle tower. The slurry discharged from the first-stage raw slurry tank is discharged into the middle tower for secondary rectification, and then the slurry is discharged into the second-stage raw slurry tank for cooling treatment. The gas discharged from the middle tower is discharged into the final tower. The slurry discharged from the second-stage raw slurry tank is discharged into the final tower for tertiary rectification, and then discharged into the cooked slurry tank to obtain cooked slurry. The purified water in the cooked slurry tank is discharged, and the tail gas from the final tower is discharged. S4: Activate the agent by passing it into the activation tank, then discharge it into the aging tank for aging, and then discharge it into the filter to separate it into filtrate and filter paste. The preparation process of the activator is as follows: Select the following components as raw materials according to the mass ratio: 25-35 parts of NaOH solution, 30-40 parts of C17H35COOH, 3-10 parts of sodium castor oil sulfonate and 50-100 parts of water. Mix and stir the above raw materials at 60-70℃ for 50-70 min, and control the speed at 200-250 r / min to obtain the activator. S5: Pass the filtrate into the sedimentation tank to separate the precipitate and clear water. Discharge the clear water and pass the filter paste and precipitate into the dryer to dry them into solids. Then, discharge the solids into the pulverizer to pulverize them. S6: The pulverized material is discharged into a cyclone separator to separate and obtain nano-calcium carbonate; S7: The slag discharged above is fed into the slag washing tank for washing with water, and the slag washing water is discharged. Then the slag is mixed with clay and purified wastewater to make brick blanks. The purified wastewater is selected from various sewages remaining in the whole process. The brick blanks are aged by the exhaust gas discharged from the three towers above to obtain finished bricks. S8: The discharged water is fed into the production line of light calcium carbonate to react with quicklime, and the slag washing water is fed into the cleaning machine as raw material for the next reaction.

2. The production process of nano-calcium carbonate powder according to claim 1, characterized in that: In step S1, steam is generated during the heating and mixing reaction, and the steam is discharged into a heat exchanger to recover the heat from the steam.

3. The production process of nano-calcium carbonate powder according to claim 1, characterized in that: In step S2, after the slurry is discharged into the fine slurry tank and a crystal guide agent is introduced, it is stirred by a stirring blade. The stirring speed is controlled at 300-600 r / min, and the stirring time is 60-120 min.

4. The production process of nano-calcium carbonate powder according to claim 1, characterized in that: In step S4, an activator is introduced into the activation tank and stirred by a stirring blade. The stirring speed is controlled at 400-600 r / min, and the stirring time is 10-15 min. During aging, the temperature is controlled at room temperature, and the aging time is controlled within 1 day.

5. The production process of nano-calcium carbonate powder according to claim 1, characterized in that: In step S5, after the filtrate is introduced into the sedimentation tank, it settles for 1-2 hours until the filtrate is clearly separated into layers. The upper clear water overflows and is discharged, while the lower sediment is collected and sent to the dryer. Filter paste is introduced simultaneously for mixing and drying. During the drying process, the temperature is controlled at 80-90℃ to dry the moisture.

6. The production process of nano-calcium carbonate powder according to claim 1, characterized in that: In step S6, the exhaust gas discharged from the cyclone separator is passed into a bag filter for dust removal. After dust removal, the gas is discharged to the outside, and the particles in the bag filter are collected.

7. The production process of nano-calcium carbonate powder according to claim 1, characterized in that: In step S7, the wastewater is treated by flocculation, filtration, sterilization and deodorization for secondary use. After the exhaust gas is used to age the brick blanks, the exhaust gas is discharged to the filtration and adsorption equipment for purification and then discharged to the outside.

8. The production process of nano-calcium carbonate powder according to claim 1, characterized in that: In step S8, all the discharged clean water and sludge washing water are collected into different water tanks, and the temperature is adjusted by heating according to actual needs.

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