An apparatus and method for preparing calcium sulfate whiskers

Abstract

The application discloses a device and method for preparing calcium sulfate whiskers, which comprises a batching tank, a raw material liquid storage tank, a first reaction chamber, a second reaction chamber, a filtering device, and a heating device, wherein the bottom of the first reaction chamber is provided with a first discharge port, the upper end and the lower end of the first reaction chamber are respectively provided with a first feeding port, the batching tank is communicated with the first feeding port at the upper end, the raw material liquid storage tank is communicated with the first feeding port at the lower end, the bottom of the outer cylinder of the second reaction chamber is provided with a second discharge port, the upper end of the second reaction chamber is provided with a second feeding port, the second discharge port is communicated with the feeding end of the filtering device, and the heating device is respectively arranged in the first reaction chamber and the second reaction chamber.

Description

Technical Field

[0001] This invention relates to the field of calcium sulfate whisker preparation technology, and in particular to an apparatus and method for preparing calcium sulfate whiskers. Background Technology

[0002] Calcium sulfate whiskers are a type of fibrous single-crystal material with high mechanical strength. They are non-toxic, stable, and inexpensive, making them suitable for various industries, including polyurethane, plastics, rubber, cement, ceramics, papermaking, adhesives, and friction materials. In recent years, the controllable preparation of calcium sulfate whiskers has received increasing attention. Currently, most methods for preparing calcium sulfate whiskers are hydrothermal methods, but these methods have high energy consumption and low yields. Atmospheric pressure acidification methods are also used, but these often require high-concentration acid solutions. These solutions can corrode reaction equipment during sample separation and drying, increasing process costs. Furthermore, as the acidity of the solution increases, the solubility of calcium sulfate increases, causing more calcium sulfate whiskers to dissolve, leading to a decrease in product yield. The acid solution after the reaction also requires further treatment before discharge. CN114197028A describes the process of converting gypsum slurry into calcium sulfate whiskers in a continuous crystallizer. CN104928752A describes the synthesis of calcium sulfate dihydrate whiskers by dissolving dolomite or limestone in an aqueous solution containing calcium ions at room temperature and pressure, and then using a crystal growth promoter containing copper ions and a liquid-phase organic catalyst. No research has been conducted on differential pressure synthesis processes using simple precipitation methods without the addition of crystallizers.

[0003] To address the aforementioned technical problems, this invention provides an apparatus and method for preparing calcium sulfate whiskers. Summary of the Invention

[0004] The purpose of this invention is to provide an apparatus and method for preparing calcium sulfate whiskers, so as to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides the following solution: The present invention provides an apparatus for preparing calcium sulfate whiskers, comprising:

[0006] A mixing tank, used for preparing a precipitant;

[0007] A raw material liquid storage tank, wherein the raw material liquid storage tank is used to store raw material liquid;

[0008] The first reaction chamber has a first discharge port at the bottom and a first feed port at the top and bottom. The mixing tank is connected to the first feed port at the top and the raw material liquid storage tank is connected to the first feed port at the bottom.

[0009] The second reaction chamber has a second discharge port at the bottom of its outer cylinder and a second inlet at the top. The first discharge port and the second inlet are connected.

[0010] The filter device has a second discharge port connected to the feed end of the filter device.

[0011] Heating devices are installed in the first reaction chamber and the second reaction chamber, respectively;

[0012] An aeration device is installed at the bottom of the first reaction chamber and the bottom of the second reaction chamber, respectively.

[0013] The first reaction chamber includes an inner cylinder and an outer cylinder. The inner cylinder is disposed inside the outer cylinder. The top of the outer cylinder is a defoaming zone. The area between the outer cylinder and the inner cylinder is a settling zone. The inner cylinder is a reaction zone. The area between the top of the inner cylinder and the top of the outer cylinder is a fluidization zone. The bottom of the outer cylinder has a first discharge port. The top and bottom of the inner cylinder have first feed ports respectively.

[0014] The structure of the second reaction chamber is the same as that of the first reaction chamber, and the second discharge port is located at the bottom of the outer cylinder of the second reaction chamber, and the second inlet is located at the top of the inner cylinder of the second reaction chamber.

[0015] According to the apparatus for preparing calcium sulfate whiskers provided by the present invention, the bottom of the outer cylinder of the first reaction chamber and the bottom of the outer cylinder of the second reaction chamber are both configured as inverted conical structures.

[0016] A method for preparing calcium sulfate whiskers includes the following steps:

[0017] Step 1: Prepare the precipitant solution or slurry in the mixing tank, and add the raw material liquid to the raw material liquid storage tank;

[0018] Step 2: Add the base liquid to the first reaction chamber and the second reaction chamber respectively, with the liquid level of the base liquid being level with the upper edge of the inner cylinder and the second inner cylinder respectively;

[0019] Step 3: Heat the base liquid to a predetermined temperature using a heating device and maintain the temperature.

[0020] Step 4: The precipitant in the mixing tank and the raw material liquid in the raw material liquid storage tank are continuously added to the inner cylinder in parallel for reaction. The aeration device in the first reactor is turned on and the air volume is adjusted so that the bottom liquid in the inner cylinder can be turned out to the outer cylinder. The reaction slurry enters the second inner cylinder through the first discharge port at the bottom of the outer cylinder.

[0021] Step 5: After the reaction slurry has reacted in the second inner cylinder for a certain period of time, the aeration device in the second reactor is turned on and the air volume is adjusted so that the bottom liquid in the inner cylinder can be turned out to the outer cylinder. The liquid then enters the filtration device through the second discharge port at the bottom of the outer cylinder of the second reactor. After filtration, calcium sulfate whisker products are obtained.

[0022] According to the method for preparing calcium sulfate whiskers provided by the present invention, in step one, the precipitant includes one or more of calcium chloride, calcium hydroxide, and calcium oxide; the concentration of the precipitant solution or slurry is 0.5-5 mol / L based on the molar concentration of calcium.

[0023] According to the method for preparing calcium sulfate whiskers provided by the present invention, in step one, the raw material solution includes one or more of sodium sulfate and potassium sulfate.

[0024] According to the preparation method for calcium sulfate whiskers provided by the present invention, in step two, the base liquid is tap water, and the temperature range of the base liquid is 20-90℃.

[0025] According to the method for preparing calcium sulfate whiskers provided by the present invention, in step five, the reaction time of the precipitant and the raw material solution in the inner cylinder is 30-120 min, and the reaction temperature range is 20-90℃.

[0026] According to the method for preparing calcium sulfate whiskers provided by the present invention, in step five, the ratio of precipitant to raw material solution is based on SO4. 2- The Ca molar ratio is 1:0.8-1.5, and the Ca is added continuously in parallel.

[0027] The present invention discloses the following technical effects:

[0028] This invention employs a non-stirred continuous reactor, which reduces the fragmentation caused by mechanical collisions, thereby improving crystal wear and ensuring stable quality of calcium sulfate whisker products.

[0029] The equipment used in this invention has a small footprint, operates at normal pressure, and has low reaction energy consumption.

[0030] This invention can continuously produce calcium sulfate whiskers without the addition of additives, breaking the barrier of the traditional hydrothermal method for intermittent production of calcium sulfate whiskers and improving the reusability of the treatment solution.

[0031] This invention is green and environmentally friendly. The method used in this invention does not use strong acids or alkalis, produces no waste gas or solid waste, and poses no threat to the environment. Compared with the atmospheric pressure acid hydrolysis method, it also uses much less water, making it even greener and more environmentally friendly.

[0032] The method described in this invention has strong applicability; similar whiskers such as magnesium carbonate, basic magnesium sulfate, and basic magnesium chloride can all be prepared using this method.

[0033] This invention uses soluble sulfate as raw material and adds additives that are produced under normal pressure and without crystallization agents to achieve continuous preparation of calcium sulfate whiskers. It overcomes the problems of energy consumption and low yield in conventional hydrothermal whisker preparation, avoids the safety hazards caused by pressure reaction, and does not introduce additional ions into the reaction system, ensuring the feasibility of reusing the filtrate after the reaction. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the apparatus for preparing calcium sulfate whiskers according to the present invention;

[0036] Figure 2 This is a scanning electron microscope image of the calcium sulfate whisker sample prepared in Example 1 of the present invention.

[0037] The components include: 1. Batching tank; 2. Raw material liquid storage tank; 3. First reaction chamber; 4. Second reaction chamber; 5. Filtration device; 6. Defoaming zone; 7. Fluidization zone; 8. Reaction zone; 9. Settling zone; and 10. Aeration device. Detailed Implementation

[0038] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] Reference Figures 1-2 The present invention provides an apparatus for preparing calcium sulfate whiskers, comprising:

[0041] Mixing tank 1 is used to prepare the precipitant.

[0042] Raw material liquid storage tank 2 is used to store raw material liquid.

[0043] The first reaction chamber 3 has a first discharge port at the bottom and a first feed port at the top and bottom. The mixing tank 1 is connected to the first feed port at the top and the raw material liquid storage tank 2 is connected to the first feed port at the bottom.

[0044] The second reaction chamber 4 has a second discharge port at the bottom of its outer cylinder and a second feed port at its upper end. The first discharge port and the second feed port are connected.

[0045] The second discharge port of the filter device 5 is connected to the feed end of the filter device 5;

[0046] Heating devices are installed in the first reaction chamber 3 and the second reaction chamber 4 respectively;

[0047] Aeration device 10 is installed at the bottom of the first reaction chamber 3 and the bottom of the second reaction chamber 4 respectively;

[0048] The first reaction chamber 3 includes an inner cylinder and an outer cylinder. The inner cylinder is located inside the outer cylinder. The top of the outer cylinder is a defoaming zone 6. The area between the outer cylinder and the inner cylinder is a settling zone 9. The inner cylinder is a reaction zone 8. The area between the top of the inner cylinder and the top of the outer cylinder is a fluidization zone 7. The bottom of the outer cylinder has a first discharge port. The top and bottom of the inner cylinder have first feed ports respectively.

[0049] The structure of the second reaction chamber 4 is the same as that of the first reaction chamber 3, and the second discharge port is located at the bottom of the outer cylinder of the second reaction chamber 4, and the second feed port is located at the top of the inner cylinder of the second reaction chamber 4.

[0050] Further optimization of the design involves setting the bottom of the outer cylinder of the first reaction chamber 3 and the bottom of the outer cylinder of the second reaction chamber 4 to an inverted conical structure.

[0051] A method for preparing calcium sulfate whiskers includes the following steps:

[0052] Step 1: Prepare a precipitant solution or slurry in the mixing tank 1, and add the raw material liquid to the raw material liquid storage tank 2;

[0053] Step 2: Add the base liquid to the first reaction chamber 3 and the second reaction chamber 4 respectively, with the liquid level of the base liquid being level with the upper edge of the inner cylinder and the second inner cylinder respectively;

[0054] Step 3: Heat the base liquid to a predetermined temperature using a heating device and maintain the temperature.

[0055] Step 4: The precipitant in the mixing tank 1 and the raw material liquid in the raw material liquid storage tank 2 are continuously added to the inner cylinder in parallel for reaction. The aeration device 10 in the first reactor is turned on and the air volume is adjusted so that the bottom liquid in the inner cylinder can be turned out to the outer cylinder. The reaction slurry enters the second inner cylinder through the first discharge port at the bottom of the outer cylinder.

[0056] Step 5: After the reaction slurry reacts in the second inner cylinder for a certain period of time, the aeration device 10 in the second reactor is turned on and the air volume is adjusted so that the bottom liquid in the inner cylinder can be turned out to the outer cylinder. The liquid enters the filter device 5 through the second discharge port at the bottom of the outer cylinder of the second reactor. After filtration by the filter device 5, calcium sulfate whisker products are obtained.

[0057] To further optimize the scheme, in step one, the precipitant includes one or more of calcium chloride, calcium hydroxide, and calcium oxide; the concentration of the precipitant solution or slurry is 0.5-5 mol / L based on the molar concentration of calcium.

[0058] To further optimize the scheme, in step one, the raw material solution includes one or more of sodium sulfate and potassium sulfate.

[0059] To further optimize the plan, in step two, the base liquid is tap water, and the temperature range of the base liquid is 20-90℃.

[0060] To further optimize the scheme, in step five, the reaction time of the precipitant and the raw material liquid in the inner cylinder is 30-120 min, and the reaction temperature range is 20-90℃.

[0061] To further optimize the scheme, in step five, the ratio of precipitant to raw material liquid is adjusted according to SO4. 2- The Ca molar ratio is 1:0.8-1.5, and the Ca is added continuously in parallel.

[0062] Example 1:

[0063] The feed solution contains a sodium sulfate solution with a sulfate concentration of 40 g / L. First, a calcium chloride solution is prepared as a precipitant with a concentration of 2 mol / L (calculated as calcium). Tap water is added to the first reaction chamber 3 and the second reaction chamber 4 of the continuous reaction apparatus, and the bottom liquid is added at the same level as the inner cylinder of the reaction chamber. The bottom liquid is heated to 60°C and maintained. The aeration devices 10 in the first reaction chamber 3 and the second reaction chamber 4 are turned on, and the gas flow is adjusted until the liquid in the inner cylinder overflows into the outer cylinder. The prepared calcium chloride solution and sodium sulfate solution are added concurrently and continuously to the continuous reaction apparatus at a stoichiometric ratio of 1:1.2. The total reaction residence time in the first reaction chamber 3 is... During the reaction, the temperature inside the first reaction chamber 3 is maintained at 60℃ for 120 minutes. The reaction slurry enters the second reaction chamber 4 under natural pressure through the pipe connected to the bottom of the first reaction chamber 3. The gas flow rate in the second reaction chamber 4 is adjusted until the liquid in the inner cylinder overflows into the outer cylinder. The reaction temperature is controlled at 60℃. The total residence time of the slurry in the second reaction chamber 4 is 120 minutes. Finally, the slurry is discharged from the bottom of the second reaction chamber 4. After filtration by the filter device 5, it becomes calcium sulfate whisker product with a purity of 99% CaSO4·2H2O and an aspect ratio of 40.

[0064] Example 2

[0065] The raw material solution contains a sodium sulfate solution with a sulfate concentration of 40 g / L. First, a calcium oxide slurry is prepared as a precipitant. The calcium oxide purity is ≥90%, and the concentration of the calcium oxide slurry is 2 mol / L (calculated as calcium). Tap water is added to the first reaction chamber 3 and the second reaction chamber 4 of the continuous reaction apparatus. The bottom liquid is added at the same level as the inner cylinder of the reaction chamber. The bottom liquid is heated to 50°C and maintained. The aeration devices 10 of the first reaction chamber 3 and the second reaction chamber 4 are turned on, and the gas flow is adjusted until the liquid in the inner cylinder overflows into the outer cylinder. The prepared calcium oxide slurry and sodium sulfate solution are added concurrently and continuously into the continuous reaction apparatus at a stoichiometric ratio of 1:0.8. The total reaction residence time in the first reaction chamber 3 is... The reaction time is 90 minutes. During the reaction, the temperature inside the first reaction chamber 3 is maintained at 50℃. The reaction slurry enters the second reaction chamber 4 under natural pressure through the pipe connected to the bottom of the first reaction chamber 3. The gas flow rate in the second reaction chamber 4 is adjusted until the liquid in the inner cylinder overflows into the outer cylinder. The reaction temperature is controlled at 50℃. The total residence time of the slurry in the second reaction chamber 4 is 90 minutes. Finally, the slurry is discharged from the bottom of the second reaction chamber 4. After filtration by the filter device 5, it becomes calcium sulfate whisker product with a purity of 95% CaSO4·2H2O and an aspect ratio of 30.

[0066] Example 3:

[0067] The raw material solution contains a potassium sulfate solution with a sulfate concentration of 20 g / L. First, a calcium hydroxide slurry is prepared as a precipitant. The calcium hydroxide purity is ≥90%, and the concentration of the calcium hydroxide slurry is 1 mol / L (calculated as calcium). Tap water is added to the first reaction chamber 3 and the second reaction chamber 4 of the continuous reaction apparatus. The bottom liquid is added at the same level as the inner cylinder of the reaction chamber. The bottom liquid is heated to 20°C and maintained. The aeration devices 10 of the first reaction chamber 3 and the second reaction chamber 4 are turned on, and the gas flow is adjusted until the liquid in the inner cylinder overflows into the outer cylinder. The prepared calcium oxide slurry and sodium sulfate solution are added concurrently and continuously to the continuous reaction apparatus. The sodium sulfate solution and calcium oxide slurry are added at a stoichiometric ratio of 1:0.8. The total reaction residence time in the first reaction chamber 3 is... The reaction time is 120 min. During the reaction, the temperature inside the first reaction chamber 3 is maintained at 20℃. The reaction slurry enters the second reaction chamber 4 under natural pressure through the pipe connected to the bottom of the first reaction chamber 3. The gas flow rate in the second reaction chamber 4 is adjusted until the liquid in the inner cylinder overflows into the outer cylinder. The reaction temperature is controlled at 20℃. The total residence time of the slurry in the second reaction chamber 4 is 120 min. Finally, the slurry is discharged from the bottom of the second reaction chamber 4 and filtered by the filter device 5 to obtain calcium sulfate whiskers. The product purity CaSO4·2H2O is 93%, and the aspect ratio of the calcium sulfate whiskers is 20.

[0068] Example 4:

[0069] The feed solution contains a potassium sulfate solution with a sulfate concentration of 60 g / L. First, a calcium chloride solution is prepared as a precipitant, with a concentration of 0.5 mol / L (calculated as calcium). Tap water is added to the first reaction chamber 3 and the second reaction chamber 4 of the continuous reaction apparatus, and the bottom liquid is added at the same level as the inner cylinder of the reaction chamber. The bottom liquid is heated to 90°C and maintained. The aeration devices 10 of the first reaction chamber 3 and the second reaction chamber 4 are turned on, and the gas flow is adjusted until the liquid in the inner cylinder overflows into the outer cylinder. The prepared calcium chloride solution and potassium sulfate solution are added concurrently and continuously to the continuous reaction apparatus at a stoichiometric ratio of 1:1.5. The total reaction residence time in the first reaction chamber 3 is... The reaction time is 30 minutes. During the reaction, the temperature inside the first reaction chamber 3 is maintained at 90℃. The reaction slurry enters the second reaction chamber 4 under natural pressure through the pipe connected to the bottom of the first reaction chamber 3. The gas flow rate in the second reaction chamber 4 is adjusted until the liquid in the inner cylinder overflows into the outer cylinder. The reaction temperature is controlled at 90℃. The total residence time of the slurry in the second reaction chamber 4 is 30 minutes. Finally, the slurry is discharged from the bottom of the second reaction chamber 4. After filtration by the filter device 5, it becomes calcium sulfate whisker product with a purity of 96% CaSO4·2H2O and an aspect ratio of 30.

[0070] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0071] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An apparatus for preparing calcium sulfate whiskers, characterized in that, include: A mixing tank (1) is used to prepare a precipitant; Raw material liquid storage tank (2), the raw material liquid storage tank (2) is used to store raw material liquid; The first reaction chamber (3) has a first discharge port at the bottom and a first feed port at the top and bottom of the first reaction chamber (3). The mixing tank (1) is connected to the first feed port at the top and the raw material liquid storage tank (2) is connected to the first feed port at the bottom. The second reaction chamber (4) has a second discharge port at the bottom of its outer cylinder and a second feed port at the top. The first discharge port and the second feed port are connected. The filter device (5) has a second discharge port connected to the feed end of the filter device (5); Heating devices are installed in the first reaction chamber (3) and the second reaction chamber (4), respectively; Aeration device (10) is installed at the bottom of the first reaction chamber (3) and the bottom of the second reaction chamber (4); The first reaction chamber (3) includes an inner cylinder and an outer cylinder. The inner cylinder is located inside the outer cylinder. The top of the outer cylinder is a defoaming zone (6). The area between the outer cylinder and the inner cylinder is a settling zone (9). The inner cylinder is a reaction zone (8). The area between the top of the inner cylinder and the top of the outer cylinder is a fluidization zone (7). The bottom of the outer cylinder is provided with the first discharge port. The top and bottom of the inner cylinder are respectively provided with the first feed port. The structure of the second reaction chamber (4) is the same as that of the first reaction chamber (3), and the second discharge port is opened at the bottom of the outer cylinder of the second reaction chamber (4), and the second feed port is opened at the top of the inner cylinder of the second reaction chamber (4).

2. The apparatus for preparing calcium sulfate whiskers according to claim 1, characterized in that: The bottom of the outer cylinder of the first reaction chamber (3) and the bottom of the outer cylinder of the second reaction chamber (4) are both configured as inverted conical structures.

3. A method for preparing calcium sulfate whiskers, based on the apparatus for preparing calcium sulfate whiskers according to any one of claims 1-2, characterized in that, The steps include the following: Step 1: Prepare a precipitant solution or slurry in the mixing tank (1) and add the raw material liquid to the raw material liquid storage tank (2). Step 2: Add the bottom liquid to the first reaction chamber (3) and the second reaction chamber (4) respectively, with the liquid level of the bottom liquid being level with the upper edge of the inner cylinder and the second inner cylinder respectively; Step 3: Heat the bottom liquid to a predetermined temperature using a heating device and maintain the temperature; turn on the aeration devices (10) of the first reaction chamber (3) and the second reaction chamber (4) and adjust the gas flow until the liquid in the inner cylinder overflows into the outer cylinder; Step 4: The precipitant in the mixing tank (1) and the raw material liquid in the raw material liquid storage tank (2) are continuously added to the inner cylinder in parallel for reaction. The reaction slurry enters the second inner cylinder through the first discharge port at the bottom of the outer cylinder. Step 5: After the reaction slurry reacts in the second inner cylinder for a certain period of time, it enters the filter device (5) through the second discharge port at the bottom of the outer cylinder of the second reactor. After filtration by the filter device (5), calcium sulfate whisker products are obtained.

4. The method for preparing calcium sulfate whiskers according to claim 3, characterized in that: In step one, the precipitant includes one or more of calcium chloride, calcium hydroxide, and calcium oxide; the concentration of the precipitant solution or slurry is 0.5-5 mol / L based on the molar concentration of calcium.

5. The method for preparing calcium sulfate whiskers according to claim 3, characterized in that: In step one, the raw material liquid includes one or more of sodium sulfate and potassium sulfate.

6. The method for preparing calcium sulfate whiskers according to claim 3, characterized in that: In step two, the base liquid is tap water, and the temperature range of the base liquid is 20-60℃.

7. The method for preparing calcium sulfate whiskers according to claim 3, characterized in that: In step five, the reaction time of the precipitant and the raw material liquid in the inner cylinder is 30-120 min, and the reaction temperature range is 20-90℃.

8. The method for preparing calcium sulfate whiskers according to claim 3, characterized in that: In step five, the ratio of precipitant to raw material liquid is determined according to SO4. 2- The Ca molar ratio is 1:0.8-1.5, and the Ca is added continuously in parallel.

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