An ultrasonic-assisted microwave method for extracting gypsum whiskers from gypsum waste

Abstract

The application relates to a device for extracting gypsum whiskers from gypsum waste by an ultrasonic-assisted microwave method, which comprises a slurry mixing tank, a pipeline ultrasonic reaction system, a microwave reaction tank and a microwave crystallization tank. A water inlet is arranged at the top of the slurry mixing tank, and a slurry agitator A is arranged in the slurry mixing tank; the pipeline ultrasonic reaction system comprises a reaction tank, an ultrasonic pipeline wrapped outside the reaction tank and a plurality of ultrasonic wave generating devices arranged in the ultrasonic pipeline; a gypsum slurry pump is arranged outside the reaction tank, a variable-frequency speed-adjusting stirring device and an ultrasonic wave induction probe are arranged in the reaction tank; one side of the ultrasonic pipeline is connected with the slurry mixing tank, and the other side is connected with the microwave reaction tank; a temperature sensor is arranged on the outer wall of the microwave reaction tank, and a slurry agitator B is arranged in the microwave reaction tank; the microwave reaction tank is connected with the microwave crystallization tank through a slurry pipeline D, and the microwave crystallization tank is connected with a drying machine. The application has low production cost, can improve production efficiency while reducing comprehensive energy consumption, and realizes comprehensive utilization of industrial waste.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and in particular to an apparatus for extracting gypsum whiskers from gypsum waste using an ultrasonic-assisted microwave method. Background Technology

[0002] Ultrasound is a sound wave with a frequency higher than 20,000 Hz. It is a mechanical longitudinal wave that propagates in an elastic medium. During propagation, it has the characteristics of good directionality, high energy, and strong penetrating power. It has great application value in fields such as detection and measurement, and medicine. It is commonly used in medical activities such as medical diagnosis, medical treatment, and rehabilitation medicine.

[0003] Microwaves are electromagnetic waves with frequencies between 300MHz and 300GHz. They are characterized by easy focusing, high directionality, and straight-line propagation, making them suitable for transmitting high-frequency signals in unobstructed free space. Microwaves have wide applications in various fields, primarily in radar systems, communication systems, industrial and agricultural production, scientific research, medicine, and biology.

[0004] Microwaves are mainly used in industrial and agricultural production for measurement and heating. Microwaves can be used to measure various non-electrical quantities, including temperature, humidity, thickness, speed, and length. A key advantage is that the measuring device does not need to contact the object being measured (non-contact measurement), making it particularly suitable for continuous monitoring and real-time automatic control on production lines. Microwave heating is a high-power application, used for sterilizing packaged food or thawing refrigerated food, heat-setting polymers, and drying food, wood, paper, and coating materials such as film. Microwave ovens are also used in homes, and their performance is becoming increasingly sophisticated. However, the industrial applications of ultrasound and microwaves have been limited due to inherent problems such as the rapid attenuation of wave intensity with increasing propagation distance.

[0005] Gypsum whiskers are fibrous single crystals of calcium sulfate, also known as gypsum fibers. They possess excellent physical and chemical properties, including high strength, high modulus, high toughness, high insulation, resistance to chemical corrosion, and ease of polymer compounding. They can be used as reinforcing fillers, friction materials, asphalt modifiers, filter materials, and paper filling materials. Due to their excellent performance and excellent price-performance ratio, they have a wide range of applications and a broad market prospect. The production of gypsum whiskers primarily uses natural gypsum as raw material, which is limited by regional constraints and is costly. Therefore, research on using industrial waste as raw materials to prepare gypsum whiskers is increasing.

[0006] Currently, gypsum whiskers are typically prepared using an acidification and acid dissolution process. This involves crushing industrial byproduct gypsum, adding sulfuric acid or hydrochloric acid for acidification to remove carbonate ions, and then cooling to crystallize. This process requires a large amount of acid, has high production costs, and consumes a significant amount of energy. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an ultrasonic-assisted microwave method for extracting gypsum whiskers from gypsum waste, which improves production efficiency and reduces overall energy consumption.

[0008] To address the aforementioned problems, the present invention provides an apparatus for extracting gypsum whiskers from gypsum waste using an ultrasonic-assisted microwave method. The apparatus comprises a slurry preparation tank, a pipeline ultrasonic reaction system, a microwave reaction vessel, and a microwave crystallization vessel. The slurry preparation tank has an inlet at its top and a slurry agitator A inside. The pipeline ultrasonic reaction system includes a reaction vessel, an ultrasonic pipeline encased in the outer wall of the reaction vessel, and several ultrasonic generators located within the ultrasonic pipeline. A gypsum slurry pump is located outside the reaction vessel, and a variable frequency speed-regulating agitator and an ultrasonic induction probe are located inside the vessel. One side of the ultrasonic pipeline has slurry pipelines A and B connected to the slurry preparation tank, and the other side has a slurry pipeline C connected to the microwave reaction vessel. A temperature sensor is installed on the outer wall of the microwave reaction vessel, and a slurry agitator B is installed inside. The microwave reaction vessel is connected to the microwave crystallization vessel via a slurry pipeline D, and the microwave crystallization vessel is connected to a dryer.

[0009] The inlet is equipped with an inlet regulating valve and a flow meter.

[0010] The slurry pipeline A is equipped with a slurry delivery pump A and a slurry regulating valve A.

[0011] A slurry backflow regulating valve is installed on the slurry pipeline B.

[0012] The slurry pipeline C is equipped with a slurry regulating valve B and a slurry delivery pump B.

[0013] The ultrasonic frequency of the pipeline ultrasonic reaction system is 20kHz~100MHz.

[0014] The microwave reaction vessel is connected to the microwave crystallization vessel via a slurry transfer pump C, a filter, and a slurry pipeline D. The reaction temperature of the microwave reaction vessel is 80~150℃.

[0015] The microwave crystallizer is connected to the dryer via a whisker removal pump.

[0016] The method for extracting gypsum whiskers using the equipment described above includes the following steps: (1) Open the material control valve and send the crushed gypsum waste into the slurry mixing tank; (2) Open the inlet water regulating valve, flow meter and slurry agitator A to adjust the slurry, and obtain gypsum waste slurry with a viscosity of 40~200 Pa·s; (3) Close the slurry reflux regulating valve and slurry regulating valve B, open the slurry regulating valve A, and the gypsum waste slurry is transported into the reaction tank by the slurry transfer pump A; (4) Turn on the ultrasonic generator to produce ultrasound; (5) Turn on the variable frequency speed control stirring device and adjust the frequency of the gypsum slurry pump so that its frequency is 1 / n times the ultrasonic frequency and n is an integer. (6) When the ultrasonic sensor detects that the frequency of the slurry in the reaction tank is 1 / n times the ultrasonic frequency and n is an integer, close the slurry regulating valve A and open the slurry regulating valve B. The slurry is then pumped into the microwave reaction tank via the slurry delivery pump B. If the slurry in the reaction tank cannot reach 1 / n times the ultrasonic frequency and n is an integer as detected by the ultrasonic sensor, open the slurry return regulating valve to return the gypsum slurry to the gypsum waste slurry preparation tank. Repeat the above steps until the ultrasonic sensor detects that the frequency of the slurry in the reaction tank reaches 1 / n times the ultrasonic frequency and n is an integer. At this point, the slurry in the reaction tank resonates with the ultrasound. (7) The slurry that has achieved resonance is stirred in the microwave reaction vessel by slurry stirrer B. Under the action of the thermal effect and resonance effect of microwaves, calcium sulfate breaks through the solubility limit and dissolves. (8) When the temperature of the slurry in the microwave reaction vessel reaches 90°C, the dissolved slurry is transported to the filter by the slurry transfer pump C to obtain a supersaturated calcium sulfate solution. (9) The supersaturated calcium sulfate solution is transported to a microwave crystallizer for cooling and crystallization. The crystallized product is discharged through whiskers and pumped to a dryer for drying, thus obtaining gypsum whisker products.

[0017] Compared with the prior art, the present invention has the following advantages: 1. The pipeline ultrasonic reaction system of this invention consists of an ultrasonic pipeline, an ultrasonic generator, a reaction tank, a gypsum slurry pump, a variable frequency speed-regulating stirring device, and an ultrasonic induction probe. The ultrasonic generator is installed in the ultrasonic pipeline to form a pipeline ultrasonic device that emits ultrasound. Based on the characteristics and mechanism of ultrasound, the slurry in the pipeline ultrasonic reaction system resonates with the ultrasound, generating a cavitation effect, thereby increasing the dissolution rate of calcium sulfate slurry, reducing filter residue, and ultimately improving production efficiency.

[0018] 2. This invention uses a microwave reaction vessel for heating, which reduces the traditional heat conduction process, resulting in fast and uniform heating, improved energy conversion efficiency, and reduced overall energy consumption.

[0019] 3. The present invention uses an ultrasonic-assisted microwave method to extract gypsum whiskers from gypsum waste by mixing the slurry with water, without the need for acid dissolution, and without causing new pollution to the environment.

[0020] 4. The present invention includes a gypsum slurry pump, and the frequency of the gypsum slurry pump can be controlled to make it an integer multiple or fractional multiple of the ultrasonic frequency of the pipeline ultrasonic reaction system and the microwave frequency of the microwave reaction tank.

[0021] 5. In this invention, the slurry in the microwave reaction vessel generates a thermal effect through molecular rotation and friction, which improves the chemical efficiency of the slurry and makes the subsequent crystallization more complete.

[0022] 6. This invention has low production costs, is environmentally friendly, and achieves comprehensive utilization of industrial waste. Attached Figure Description

[0023] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0024] Figure 1 This is a schematic diagram of the structure of the present invention.

[0025] Figure 2 This is a graph showing the relationship between sulfate ion concentration and dissolution kinetics in this invention.

[0026] In the diagram: 1—Slurry mixing tank; 2—Slurry agitator A; 3—Inlet water regulating valve; 4—Flow meter; 5—Material control valve; 6—Slurry transfer pump A; 7—Slurry regulating valve A; 8—Slurry reflux regulating valve; 9—Ultrasonic pipeline; 10—Ultrasonic generating device; 11—Reaction tank; 12—Gypsum slurry pump; 13—Variable frequency speed regulating agitator; 14—Ultrasonic induction probe; 15—Slurry regulating valve B; 16—Slurry transfer pump B; 17—Microwave reaction tank; 18—Temperature sensor; 19—Slurry agitator B; 20—Slurry transfer pump C; 21—Filter; 22—Microwave crystallizing tank; 23—Whisker removal pump; 24—Dryer. Detailed Implementation

[0027] like Figure 1 As shown, an apparatus for extracting gypsum whiskers from gypsum waste using an ultrasonic-assisted microwave method is disclosed. The apparatus includes a slurry preparation tank 1, a pipeline ultrasonic reaction system, a microwave reaction vessel 17, and a microwave crystallization vessel 22.

[0028] A water inlet is provided above the slurry mixing tank 1, and a slurry agitator A2 is installed inside it; the pipeline ultrasonic reaction system includes a reaction tank 11, an ultrasonic pipeline 9 wrapped around the outer wall of the reaction tank 11, and several ultrasonic generating devices 10 installed inside the ultrasonic pipeline 9; a gypsum slurry pump 12 is provided outside the reaction tank 11, and a variable frequency speed regulating agitator 13 and an ultrasonic induction probe 14 are provided inside the tank; a slurry pipeline A and a slurry pipeline B are respectively provided on one side of the ultrasonic pipeline 9 and connected to the slurry mixing tank 1, and a slurry pipeline C is provided on the other side and connected to the microwave reaction tank 17; a temperature sensor 18 is provided on the outer wall of the microwave reaction tank 17, and a slurry agitator B19 is installed inside; the microwave reaction tank 17 is connected to the microwave crystallization tank 22 through the slurry pipeline D, and the microwave crystallization tank 22 is connected to a dryer 24.

[0029] Among them, the water inlet is equipped with an inlet regulating valve 3 and a flow meter 4, which play a role in linkage control.

[0030] The slurry pipeline A is equipped with a slurry delivery pump A6 and a slurry regulating valve A7.

[0031] A slurry backflow regulating valve 8 with a feedback mechanism is installed on slurry pipeline B, which can coordinate the frequency inside the tank and complete intelligent control.

[0032] The slurry pipeline C is equipped with a slurry regulating valve B15 and a slurry delivery pump B16.

[0033] The ultrasonic frequency of the pipeline ultrasonic reaction system is 20kHz~100MHz.

[0034] The microwave reaction vessel 17 is connected to the microwave crystallization vessel 22 via the slurry transfer pump C20, the filter 21 and the slurry pipeline D. The reaction temperature of the microwave reaction vessel 17 is 80~150℃.

[0035] The microwave crystallizer 22 is connected to the dryer 24 via the whisker removal pump 23.

[0036] In this invention, the ultrasonic generator 10 is manufactured by Kunshan Hengyou Yinda Machinery Technology Co., Ltd.; and the microwave reaction vessel 17 is manufactured by Xi'an Shengda Environmental Protection Equipment Co., Ltd.

[0037] The method for extracting gypsum whiskers using this equipment includes the following steps: (1) Open the material control valve 5 and send the crushed gypsum waste into the slurry mixing tank 1; (2) Open the inlet regulating valve 3, flow meter 4 and slurry agitator A2 to adjust the slurry, and obtain gypsum waste slurry with a viscosity of 40~200 Pa·s; (3) Close the slurry reflux regulating valve 8 and the slurry regulating valve B15, and open the slurry regulating valve A7. The gypsum waste slurry is transported into the reaction tank 11 by the slurry transfer pump A6. (4) Turn on the ultrasonic generator 10 to generate ultrasound; (5) Turn on the variable frequency speed regulating stirring device 13 and adjust the frequency of the gypsum slurry pump 12 so that its frequency is 1 / n times the ultrasonic frequency and n is an integer. (6) When the ultrasonic sensor 14 detects that the frequency of the slurry in the reaction tank 11 is 1 / n times the ultrasonic frequency and n is an integer, the slurry regulating valve A7 is closed and the slurry regulating valve B15 is opened, and the slurry is transported into the microwave reaction tank 17 by the slurry transfer pump B16; if the slurry in the reaction tank 11 cannot reach 1 / n times the ultrasonic frequency and n is an integer as detected by the ultrasonic sensor 14 at this time, the slurry return regulating valve 8 is opened, so that the gypsum slurry returns to the gypsum waste slurry tank 1; repeat the above work until the ultrasonic sensor 14 detects that the frequency of the slurry in the reaction tank 11 is all 1 / n times the ultrasonic frequency and n is an integer, at which time the slurry in the reaction tank 11 resonates with the ultrasound; (7) The slurry that has achieved resonance is stirred in microwave reaction vessel 17 by slurry stirrer B19. Under the action of microwave thermal effect and resonance effect, calcium sulfate breaks through the solubility limit and dissolves. (8) When the temperature of the slurry in the microwave reaction vessel 17 reaches 90°C, the dissolved slurry is transported to the filter 21 by the slurry transfer pump C20 for filtration to obtain a supersaturated calcium sulfate solution. (9) The supersaturated calcium sulfate solution is transported to microwave crystallization tank 22 for cooling and crystallization. The crystallized product is sent to dryer 24 via whisker removal pump 23 for drying, thus obtaining gypsum whisker product.

[0038] Working principle: Based on the characteristics and mechanism of ultrasound, the slurry in the pipeline ultrasonic reaction system resonates with the ultrasound, generating a cavitation effect, thereby improving the dissolution rate of calcium sulfate slurry.

[0039] Experiments analyzing sulfate concentration and dissolution kinetics show that under conventional mechanical stirring conditions ( Figure 2 -X1), sulfate ion concentration (SO4) 2− The dissolution rate exhibits an exponential growth trend over time, with a high initial dissolution rate (0.07 mol / L concentration increase from 0 to 30 minutes), followed by a gradual decrease, reaching near equilibrium concentration (1.18 mol / L) at approximately 70 minutes. This phenomenon conforms to a first-order kinetic model (C(t) = Ceq − (Ceq − C0)e − kt), indicating that the dissolution process is controlled by the solid-liquid interface reaction rate. After introducing ultrasonic assistance (…), Figure 2The dissolution kinetics were significantly improved: the sulfate concentration reached equilibrium (1.18 mol / L) within 50 minutes, and the initial dissolution rate increased by approximately 40% (the concentration increment increased to 0.08 mol / L from 0 to 30 minutes). The cavitation effect of ultrasound accelerated dissolution; the localized high-pressure microjets generated by the collapse of cavitation bubbles disrupted the passivation layer on the surface of calcium sulfate particles, increasing the effective reaction area. Furthermore, cavitation-induced turbulent diffusion reduced the boundary layer thickness, promoting ion migration from the solid phase to the liquid phase and thus increasing the dissolution rate.

[0040] Experiments on the effect of conductivity on ion migration show that: changes in conventional conductivity are significantly positively correlated with sulfate concentration. Figure 2 -Y1), but conductivity under ultrasound assistance ( Figure 2 The growth slope of -Y2 was higher (the incremental ratio increased from 50 μS / cm·0.01 mol / L to 60 μS / cm·0.01 mol / L). This indicates that ultrasound not only accelerates dissolution but also improves ion dispersion, i.e., cavitation disrupts the aggregation of ion clusters or undissolved particles in the solution, reduces ion migration resistance, enhances ion activity coefficients, and increases the reaction rate.

[0041] Comparing the two sets of data, ultrasound + microwave assistance shortened the dissolution time by approximately 28.6% (from 70 minutes to 50 minutes) and increased the conductivity saturation value by 4.0% (from 5060 μS / cm to 5370 μS / cm), effectively improving the dissolution rate of calcium sulfate slurry.

Claims

1. An apparatus for extracting gypsum whiskers from gypsum waste using an ultrasonic-assisted microwave method, characterized in that: The equipment includes a slurry preparation tank (1), a pipeline ultrasonic reaction system, a microwave reaction tank (17), and a microwave crystallization tank (22); the slurry preparation tank (1) is provided with a water inlet at the top and a slurry agitator A (2) is provided inside; the pipeline ultrasonic reaction system includes a reaction tank (11), an ultrasonic pipeline (9) wrapped around the outer wall of the reaction tank (11), and several ultrasonic generating devices (10) installed in the ultrasonic pipeline (9); a gypsum slurry pump (12) is provided outside the reaction tank (11), and a variable frequency speed regulating agitator is provided inside the tank. (13) and ultrasonic induction probe (14); one side of the ultrasonic pipe (9) is provided with slurry pipe A and slurry pipe B connected to the slurry tank (1), and the other side is provided with slurry pipe C connected to the microwave reaction tank (17); a temperature sensor (18) is provided on the outer wall of the microwave reaction tank (17), and a slurry stirrer B (19) is installed inside; the microwave reaction tank (17) is connected to the microwave crystallization tank (22) through slurry pipe D, and the microwave crystallization tank (22) is connected to a dryer (24).

2. The apparatus for extracting gypsum whiskers from gypsum waste using an ultrasonic-assisted microwave method as described in claim 1, characterized in that: The inlet is equipped with an inlet regulating valve (3) and a flow meter (4).

3. The apparatus for extracting gypsum whiskers from gypsum waste using an ultrasonic-assisted microwave method as described in claim 1, characterized in that: The slurry pipeline A is equipped with a slurry delivery pump A (6) and a slurry regulating valve A (7).

4. The apparatus for extracting gypsum whiskers from gypsum waste using an ultrasonic-assisted microwave method as described in claim 3, characterized in that: A slurry backflow regulating valve (8) is installed on the slurry pipeline B.

5. The apparatus for extracting gypsum whiskers from gypsum waste using an ultrasonic-assisted microwave method as described in claim 1, characterized in that: The slurry pipeline C is equipped with a slurry regulating valve B (15) and a slurry delivery pump B (16).

6. The apparatus for extracting gypsum whiskers from gypsum waste using an ultrasonic-assisted microwave method as described in claim 5, characterized in that: The ultrasonic frequency of the pipeline ultrasonic reaction system is 20kHz~100MHz.

7. The apparatus for extracting gypsum whiskers from gypsum waste using an ultrasonic-assisted microwave method as described in claim 1, characterized in that: The microwave reaction vessel (17) is connected to the microwave crystallization vessel (22) via the slurry transfer pump C (20) and the filter (21) through the slurry pipeline D. The reaction temperature of the microwave reaction vessel (17) is 80~150℃.

8. The apparatus for extracting gypsum whiskers from gypsum waste using an ultrasonic-assisted microwave method as described in claim 1, characterized in that: The microwave crystallizer (22) is connected to the dryer (24) via a whisker removal pump (23).

9. A method for extracting gypsum whiskers using the equipment described in any one of claims 1 to 8, comprising the following steps: (1) Open the material control valve (5) and send the crushed gypsum waste into the slurry tank (1); (2) Open the inlet regulating valve (3), flow meter (4) and slurry agitator A (2) to adjust the slurry, and obtain gypsum waste slurry with a viscosity of 40~200 Pa·s; (3) Close the slurry reflux regulating valve (8) and the slurry regulating valve B (15), and open the slurry regulating valve A (7). The gypsum waste slurry is transported into the reaction tank (11) by the slurry transfer pump A (6). (4) Turn on the ultrasonic generator (10) to generate ultrasound; (5) Turn on the variable frequency speed regulating stirring device (13) and adjust the frequency of the gypsum slurry pump (12) so that its frequency is 1 / n times the ultrasonic frequency and n is an integer. ⑹ When the ultrasonic sensor (14) detects that the frequency of the slurry in the reaction tank (11) is 1 / n times the ultrasonic frequency and n is an integer, close the slurry regulating valve A (7) and open the slurry regulating valve B (15), and send the slurry into the microwave reaction tank (17) via the slurry transfer pump B (16); if the slurry in the reaction tank (11) cannot reach 1 / n times the ultrasonic frequency and n is an integer as detected by the ultrasonic sensor (14), open the slurry return regulating valve (8) to return the gypsum slurry to the gypsum waste slurry tank (1); repeat the above work until the ultrasonic sensor (14) detects that the frequency of the slurry in the reaction tank (11) reaches 1 / n times the ultrasonic frequency and n is an integer, at which point the slurry in the reaction tank (11) resonates with the ultrasound; (7) The slurry that has completed resonance is stirred in the microwave reaction vessel (17) by the slurry stirrer B (19). Under the action of the thermal effect and resonance effect of microwave, calcium sulfate breaks through the solubility limit and dissolves. (8) When the temperature of the slurry in the microwave reaction vessel (17) reaches 90°C, the dissolved slurry is transported to the filter (21) by the slurry transfer pump C (20) for filtration to obtain supersaturated calcium sulfate solution; (9) The supersaturated calcium sulfate solution is transported to a microwave crystallizer (22) for cooling and crystallization. The crystallized product is sent to a dryer (24) via a whisker removal pump (23) for drying, thus obtaining gypsum whisker products.

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