Preparation method of calcium carbonate fiber

Abstract

The invention provides a preparation method of calcium carbonate fibers. Comprising the following steps: S1, preparing Ca (OH) 2 water slurry; adding carbon nanotubes and MgC12, and fully mixing under the action of stirring; s2, heating to 85-90 DEG C, continuously introducing CO2 gas, enabling Ca (OH) 2 and CO2 gas to react to form fiber whiskers, loading the fiber whiskers to carbon nanotubes for growth, and continuously reacting to form calcium carbonate fibers; and S3, washing and filtering the calcium carbonate fiber to obtain the product calcium carbonate fiber. The reaction time is obviously shorter than that in the prior art, which shows that the reaction rate is increased by reducing the addition of MgC l2; and the carbon nanotubes are added to assist the formation of the whiskers, so that the growth of the calcium carbonate whiskers and the growth of the fibers are very stable, the problems of obvious agglomeration and caking are avoided, and the problem that in the prior art, the growth of the fibers can only be controlled by adding MgC12 is solved. Furthermore, the consumption of the material is reduced by reducing the addition of MgCl2, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to a preparation technology of calcium carbonate fiber, and in particular to a technology for improving the production efficiency of calcium carbonate fiber based on the addition of carbon nanotubes. Background Art

[0002] Calcium carbonate fiber is a fiber material with calcium carbonate as the main component. It has good biocompatibility, non-toxicity and environmental protection characteristics, and is often used in many fields, such as construction, medicine, agriculture and material science. In the construction industry, calcium carbonate fiber can be used as a reinforcing material to improve the performance of concrete and other building materials. In the medical field, it can be used as a biomaterial for tissue engineering or drug delivery systems. In agriculture, it may be used as a soil conditioner or plant nutrient supplement. Due to its environmental protection characteristics, calcium carbonate fiber has also attracted attention in the development of sustainable materials.

[0003] In the prior art, Ca(OH) 2 The water slurry is fed with CO 2 In order to obtain calcium carbonate fibers by gas, and in order to control the slow growth of fibers to obtain qualified fibers, magnesium ions are added to the reaction solution. The growth time of calcium carbonate is inhibited by the action of magnesium ions in the solution, thereby avoiding the formation of agglomerates and lumps when calcium carbonate reacts at local locations, that is, qualified calcium carbonate fiber products are obtained by controlling the reaction rate.

[0004] However, this method consumes magnesium ions such as MgCl 2 The amount is large, which increases the production cost; in addition, this control method causes the reaction rate to decrease artificially, making continuous production impossible and reducing the efficiency of continuous production. Summary of the invention

[0005] In order to solve the problems existing in the above-mentioned technology, the present invention provides a method for preparing calcium carbonate fiber.

[0006] The following steps are included:

[0007] S1: Preparation of Ca(OH) 2 Water slurry; adding carbon nanotubes and MgCl 2 , the amount of carbon nanotubes added is Ca(OH) 2 0.1% to 0.01% of dry material, MgCl 2 The amount of Ca(OH) added is 2 10% to 50% of dry materials, thoroughly mixed by stirring;

[0008] S2: Heat to 85 to 90°C and continuously introduce CO 2 Gas, Ca(OH) 2 With CO2 The gas reacts to form fiber whiskers, which are then loaded onto carbon nanotubes for growth, and then continue to react to form calcium carbonate fibers;

[0009] S3: washing and filtering the calcium carbonate fibers to obtain product calcium carbonate fibers.

[0010] Preferably, Ca(OH) 2 The concentration of the water slurry is controlled at 2 to 5%.

[0011] Preferably, the carbon nanotubes have an outer diameter of 6 to 12 nm and a length of 5 μm to 20 μm; the surface area of ​​the carbon nanotubes is not less than 200 m 2 / g.

[0012] Preferably, Ca(OH) 2 The addition of water slurry is divided into two stages. The first stage uses low concentration Ca(OH) 2 The water slurry is reacted, and the second stage uses a high concentration of Ca(OH) 2 The water slurry is reacted;

[0013] The first stage lasts for 5 to 10 minutes; the low concentration of Ca(OH) 2 The concentration of the water slurry was less than 2.5%.

[0014] Preferably, Ca(OH) 2 The water slurry runs in the circulating long cylinder structure, and a spiral stirring rod is arranged in the circulating long cylinder structure. The spiral stirring rod has an air outlet in the length direction, and CO is discharged into the long cylinder structure through the air outlet. 2 gas.

[0015] Preferably, the upstream side of the circulating long tube structure has an input pipe, and the downstream side of the long tube structure has an output pipe; the circulating long tube structure is connected to a separation sedimentation tank, and the separation sedimentation tank is connected to a recovery tank.

[0016] Preferably, the upstream side of the circulating long tube structure has a low concentration input pipe and a high concentration input pipe; during the first stage reaction, Ca(OH) is input through the low concentration input pipe. 2 Water slurry, in the second stage reaction, input Ca(OH) through the high concentration input pipe 2 Water slurry.

[0017] The reaction time of the present invention is significantly shorter than that of the prior art, which indicates that by reducing MgCl 2The addition of MgCl increases the reaction rate; and the addition of carbon nanotubes assists in the formation of whiskers, which makes the growth of calcium carbonate whiskers and fibers very stable, without obvious agglomeration and agglomeration problems, overcoming the existing technology that can only be achieved by MgCl 2 Further, by reducing MgCl 2 The addition of this material reduces the consumption of this material and reduces production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a physical picture of the appearance of the calcium carbonate fiber prepared in the embodiment of the present invention.

[0019] Figure 2 It is a schematic diagram of the preparation equipment used in the preparation method of calcium carbonate fiber of the present invention.

[0020] Figure 3 It is a schematic diagram of a preferred solution of the preparation equipment used in the preparation method of calcium carbonate fiber of the present invention. DETAILED DESCRIPTION

[0021] First embodiment:

[0022] The present invention provides a method for preparing calcium carbonate fiber, comprising the following steps:

[0023] S1: Preparation of Ca(OH) 2 Water slurry; Ca(OH) 2 The concentration of the water slurry was 5%.

[0024] Addition of carbon nanotubes and MgCl 2 , the amount of carbon nanotubes added is Ca(OH) 2 0.1% to 0.01% of dry material, MgCl 2 The amount of Ca(OH) added is 2 10% to 50% of the dry material is mixed thoroughly by stirring; preferably, the size of the carbon nanotubes is 6 to 12 nm in outer diameter and 5 μm to 20 μm in length; the surface area of ​​the carbon nanotubes is not less than 200 m 2 / g. Carbon nanotubes are purchased from the market.

[0025] S2: Heat to 85 to 90°C and continuously introduce CO 2 Gas, Ca(OH) 2 With CO 2 The gas reacts to form fiber whiskers, which are then loaded onto carbon nanotubes for growth, and then continue to react to form calcium carbonate fibers;

[0026] S3: washing and filtering the calcium carbonate fibers to obtain product calcium carbonate fibers.

[0027] Specifically, the amount of carbon nanotubes added is Ca(OH) 2 0.1% to 0.01% of the dry material was used to obtain Example 1, Example 2 and Example 3 in the proportions of 0.01%, 0.05% and 0.1% respectively; MgCl in these examples 2 The addition amount is 20%.

[0028] In addition, MgCl 2 The amount of Ca(OH) added is 2 10% to 50% of the dry material is set to different proportions, namely 10%, 20% and 40%, corresponding to Example 4, Example 5 and Example 6 respectively; the added amount of carbon nanotubes in these examples is 0.05%.

[0029] The control example is different from the previous examples in that the carbon nanotubes added in the control example are 0 and the MgCl 2 The amount of Ca(OH) added is 2 50%, 100%, and 200% of the dry material correspond to Control Example 1, Control Example 2, and Control Example 3, respectively.

[0030] Group / Observation Reaction time Appearance observation Example 1 29-30min qualified Example 2 22-23min qualified Example 3 19-20min qualified Example 4 17-18min qualified Example 5 22-23min qualified Example 6 25-26min qualified Comparative Example 1 40-50min qualified Comparative Example 2 More than 50min qualified Comparative Example 3 More than 70 minutes qualified

[0031] The reaction time is calculated from the CO 2 Gas starts, and then to Ca(OH) 2 The concentration of the water slurry is less than 0.5%. Qualified means that the performance and appearance of the obtained calcium carbonate fiber meet the requirements. Calcium carbonate fiber is loose white powder, and its microscopic morphology is a needle-like object. Figure 1 Shown is a physical picture of the appearance of the calcium carbonate fiber prepared by the present invention.

[0032] Any group of the above embodiments and control examples includes at least 5 experimental examples, and the reaction time is the interval range of the reaction time of multiple equivalent experimental examples.

[0033] As can be seen from the table above, the reaction times in Examples 1 to 3 and Examples 4 to 6 are significantly shorter than those in Comparative Examples 1 to 3, which indicates that by reducing MgCl 2 The addition of MgCl2 increases the reaction rate; and the addition of carbon nanotubes assists in the formation of whiskers, which makes the growth of calcium carbonate whiskers and fibers very stable, without obvious agglomeration and agglomeration problems, overcoming the existing technology that can only be achieved by MgCl2 2 Further, by reducing MgCl 2 The addition of this material reduces the consumption of this material and reduces production costs.

[0034] Second embodiment:

[0035] Preferably, if Figure 2 As shown, in this embodiment, Ca(OH) 2 The water slurry runs in the circulating long tube structure 10, and Ca(OH) is injected into the circulating long tube structure 10 through the storage tank 50. 2 A spiral stirring rod 11 is arranged in the circulating long cylindrical structure 10, and an air outlet 12 is provided in the length direction of the spiral stirring rod 11, through which CO is discharged into the long cylindrical structure 10 2 gas.

[0036] Preferably, the upstream side of the circulating long cylindrical structure 10 has an input pipe 13 , and the downstream side of the long cylindrical structure 10 has an output pipe 14 ; the circulating long cylindrical structure 10 is connected to a separation sedimentation tank 15 , and the separation sedimentation tank 15 is connected to a recovery tank 16 .

[0037] The storage tank 50 adds the configured Ca(OH) into the circulation long tube structure 10 through the connected input pipe 13. 2 Water slurry, prepared Ca(OH) 2 The required MgCl was also added to the water slurry. 2 and carbon nanotubes. After being added into the circulating long tube structure 10, it is stirred and discharged into the CO 2 The gas reacts and after a certain period of time, it is discharged into the separation sedimentation tank 15 through the output pipe 14. The refined and separated lower layer of fixed calcium carbonate fibers can be discharged into the recovery tank 16 below for collection, while the upper layer of liquid water can be sucked away and discharged through the negative pressure suction pipe.

[0038] It should be noted that electronic valves and manual valves are provided at the connection positions such as the input pipe 13 and the output pipe 14 as required.

[0039] Third embodiment:

[0040] Preferably, if Figure 3 As shown, the upstream side of the circulating long tube structure 10 of this embodiment has a low concentration input pipe 21 and a high concentration input pipe 22; the low concentration input pipe 21 and the high concentration input pipe 22 correspond to different storage tanks respectively.

[0041] During the first stage reaction, Ca(OH) is input through the low concentration input pipe 21. 2 Water slurry, in the second stage reaction, inputs Ca(OH) through the high concentration input pipe 22 2 Water slurry. Ca(OH) 2 The addition of water slurry is divided into two stages. The first stage uses low concentration Ca(OH) 2 The water slurry is reacted, and the second stage uses a high concentration of Ca(OH) 2 The water slurry is reacted;

[0042] The first stage lasts for 5 to 10 minutes; the low concentration of Ca(OH) 2 The concentration of the water slurry is less than 2.5%. This is to better control the whisker growth, that is, through the low concentration of Ca(OH) 2 water slurry, so that it is in the presence of CO 2 When the gas reacts, whiskers can be better formed on the carbon nanotubes and gradually grow to form a fiber structure, avoiding the problem of excessive concentration at the beginning causing local agglomeration and failure to form a good fiber structure, thereby improving product quality.

[0043] Furthermore, there is a circulation branch pipe 23, which returns the slurry on the downstream side of the circulation long tube structure 10 to the upstream side of the circulation long tube structure 10 by means of a pump (omitted in the figure), thus forming a circulation motion, which is more conducive to the reaction.

Claims

1. A method for preparing calcium carbonate fiber, characterized in that: The following steps are included: S1: Prepare a Ca(OH)2 water slurry; add carbon nanotubes and MgCl2, wherein the amount of carbon nanotubes added is 0.1% to 0.01% of the dry Ca(OH)2 material, and the amount of MgCl2 added is 10% to 50% of the dry Ca(OH)2 material, and mix thoroughly by stirring; S2: heating to 85 to 90°C, continuously introducing CO2 gas, Ca(OH)2 reacts with CO2 gas to form fiber whiskers, the fiber whiskers are loaded onto the carbon nanotubes for growth, and continuously react to form calcium carbonate fibers; S3: washing and filtering the calcium carbonate fibers to obtain product calcium carbonate fibers.

2. The method for preparing calcium carbonate fiber according to claim 1, characterized in that: The concentration of Ca(OH)2 water slurry is controlled at 2% to 5%.

3. The method for preparing calcium carbonate fiber according to claim 1, characterized in that: The size of carbon nanotubes is 6 to 12 nm in outer diameter and 5 to 20 μm in length; the surface area of ​​carbon nanotubes is not less than 200 m 2 / g.

4. The method for preparing calcium carbonate fiber according to claim 3, characterized in that: The addition of Ca(OH)2 aqueous slurry is divided into two stages. The first stage uses low-concentration Ca(OH)2 aqueous slurry for reaction, and the second stage uses high-concentration Ca(OH)2 aqueous slurry for reaction. The time of the first stage is 5 to 10 minutes; the concentration of the low-concentration Ca(OH)2 water slurry in the first stage is less than 2.5%.

5. The method for preparing calcium carbonate fiber according to claim 1, characterized in that: The Ca(OH)2 water slurry runs in a circulating long cylinder structure, and a spiral stirring rod is arranged in the circulating long cylinder structure. The spiral stirring rod has an air outlet in the length direction, and CO2 gas is discharged into the long cylinder structure through the air outlet.

6. The method for preparing calcium carbonate fiber according to claim 5, characterized in that: The upstream side of the circulating long tube structure is provided with an input pipe, and the downstream side of the long tube structure is provided with an output pipe; the circulating long tube structure is connected to a separation sedimentation tank, and the separation sedimentation tank is connected to a recovery tank.

7. The method for preparing calcium carbonate fiber according to claim 6, characterized in that: The upstream side of the circulating long tube structure has a low-concentration input pipe and a high-concentration input pipe; during the first stage reaction, Ca(OH)2 water slurry is input through the low-concentration input pipe, and during the second stage reaction, Ca(OH)2 water slurry is input through the high-concentration input pipe.

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