Recyclable induced crystallization agent as well as preparation method and application thereof

Abstract

The invention provides a recyclable induced crystallization agent as well as a preparation method and application thereof. The recyclable induced crystallization agent is prepared from a water-soluble binder, a thickening agent, Fe3O4 powder, activated carbon powder and induced crystallization material powder. Through the cooperation of the cathode structure design and the recyclable induced crystallization agent, the difficulty that scale on the surface of the cathode is difficult to remove in a traditional electrochemical hardness removal method is overcome, and the service life of the cathode is effectively prolonged; the deslagging of the electrolytic bath is linked with the magnetic separation system and the electric flocculation-cyclone centrifugal system, so that the solid-liquid separation efficiency is high, and the system can continuously operate for a long time; and generated precipitates can be recycled, so that resources are saved.

Description

Technical Field

[0001] The present invention belongs to the field of metallurgical chemistry, and particularly relates to a recyclable induced crystallization agent and its preparation method and application. Background Art

[0002] The electrochemical hardening removal technology is a common industrial high-hard wastewater treatment technology, which has the advantages of fast treatment speed, no secondary pollution, simple operation, etc. However, after long-term use, scaling will occur on the cathode surface due to the precipitation of hardness ions, such as the formation of precipitates such as calcium carbonate and magnesium hydroxide. Scaling will hinder the transfer and reaction of ions on the electrode surface, reduce the electrolysis efficiency, increase energy consumption, and require regular cleaning of the electrode, affecting the continuous operation of the equipment. Therefore, it is of great significance to develop a product and method that can solve the above technical problems. Summary of the Invention

[0003] The first object of the present invention is to provide a recyclable induced crystallization agent; the second object is to provide a preparation method of the recyclable induced crystallization agent; the third object is to provide an application of the recyclable induced crystallization agent.

[0004] The first object of the present invention is achieved as follows. The recyclable induced crystallization agent is composed of a water-soluble binder, a thickener, Fe3O4 powder, activated carbon powder, and induced crystallization material powder.

[0005] The second object of the present invention is achieved as follows, including a pretreatment step, a preparation step of the cementitious matrix, and a formulation step, specifically including: A. Pretreatment: Mix the Fe3O4 powder, activated carbon powder, and induced crystallization material powder in the formula ratio, and then perform ball milling and sieving through a 400-mesh sieve to obtain material a; B. Preparation of the cementitious matrix: 1) Mix the water-soluble binder and thickener in the formula ratio to obtain material b; 2) Dissolve material b in deionized water 10 - 15 times the mass of material b under high-speed stirring at a rotation speed of 10000 - 12000 r / min and stir for 15 - 25 min to obtain a colloidal matrix c; C. Formulation: Add material a to the colloidal matrix c under high-speed stirring at a rotation speed of 10000 - 12000 r / min and continue stirring for 10 - 30 min to obtain an induced crystallization slurry, that is, the target recyclable induced crystallization agent.

[0006] The third object of the present invention is achieved as follows. The recyclable induced crystallization agent is applied in an electrochemical hardening removal system with a self-cleaning function, and its specific operation mode is as follows: Stage 1 (Preparation of induced crystallization slurry): The induced crystallization slurry (hereinafter referred to as slurry) is mechanically stirred and mixed by deionized water, water-soluble binder, thickener, Fe3O4 powder, activated carbon powder, and induced crystallization material powder.

[0007] Stage 2 (Slurry injection): The slurry supply system injects the slurry into the cathode cavity of the electrochemical hardening removal device at a certain pressure, forming a protrusion at the micropores on the cathode surface and flowing out at a certain speed.

[0008] Stage 3 (Electrochemical hardening removal): Current is passed through, and water is electrolyzed on the cathode surface and the slurry surface. Under the action of the induced crystallization material, Ca 2+ / Mg 2+ Scales on the protrusion surface.

[0009] Stage 4 (Scale layer shedding): As the slurry flows out and more scales form on the surface, the binder gradually dissolves, causing the strength of the slurry to decrease. Under the action of gravity and the scouring of water flow, the slurry and the scales fall off from the cathode surface, achieving the purpose of self-cleaning.

[0010] Stage 5 (Precipitation separation): Larger particles of precipitation accumulate at the bottom of the electrochemical hardening removal system and are discharged through the slag discharge port. The magnetic separation system separates the tiny magnetic precipitates, and the inclined tube sedimentation tank further separates the non-magnetic tiny precipitates. The wastewater after precipitation separation is discharged from the outlet pipe.

[0011] Stage 6 (Precipitation utilization): The large particles and magnetic precipitates can be recycled as raw materials for the slurry after drying, grinding, and screening.

[0012] The action mechanism of the recyclable induced crystallization agent described in the present invention: The recyclable induced crystallization agent is mechanically stirred and mixed by deionized water, water-soluble binder, thickener, Fe3O4 powder, activated carbon powder, and induced crystallization material powder. The water-soluble binder gives the slurry certain water solubility and viscosity. The thickener further enhances the viscosity of the slurry and can maintain a certain strength under the scouring of water flow. The Fe3O4 powder makes the slurry magnetic and conductive. The induced crystallization material powder makes the scale tend to form on the slurry surface, avoiding scale formation on the cathode surface. The activated carbon powder can further enhance the conductivity and induced crystallization performance of the slurry and can adsorb some other pollutants (heavy metals, organic matters, etc.) in the wastewater. During the hardening removal process, as the slurry continuously flows out, scales gradually form on the slurry surface. At the same time, the gradual dissolution of the water-soluble binder and thickener causes the strength of the mixed slurry to gradually decrease. Finally, under the action of gravity and the scouring of water flow, the mixed slurry and the surface scales fall off by themselves, achieving the purpose of self-cleaning. Since the fallen precipitate contains the induced crystallization slurry and the formed scale can be used as the induced crystallization material, it can be processed and recycled as the raw material of the induced crystallization slurry.

[0013] Advantages of the present invention: 1. Through the coordination of the cathode structure design and the recyclable induced crystallization agent, the difficulty of scale removal on the cathode surface in traditional electrochemical hard removal methods is overcome, effectively improving the cathode life.

[0014] 2. The slag discharge of the electrolytic cell is linked with the magnetic separation system and the electrocoagulation - cyclone centrifugation system, with high solid - liquid separation efficiency, and the system can operate continuously for a long time.

[0015] 3. The generated precipitate can be recycled, saving resources. Description of the Drawings

[0016] Figure 1 is a schematic structural diagram of the electrochemical hard removal device of the present invention; Figure 2 is a schematic diagram of the electrochemical hard removal system with self - cleaning function of the present invention; Figure 3 is a schematic structural diagram of the cathode plate of the present invention; In the figure, 1 - electrochemical hard removal device, 2 - magnetic separation system, 3 - cyclone centrifuge, 4 - electrocoagulation system, 5 - material recovery system, 6 - electrolytic cell, 7 - water inlet pipe, 8 - water outlet pipe, 9 - induced crystallization slurry, 10 - water outlet pipeline, 11 - CO2 intelligent addition system, 12 - anode plate, 13 - cathode plate, 14 - electrode plate power supply, 15 - slag discharge port, 16 - micropores, 17 - storage bin, 18 - constant pressure pump, 19 - intelligent pressure control system, 20 - control cabinet Ⅰ, 21 - on - line hardness monitor, 22 - on - line PH monitor, 23 - control cabinet Ⅱ, 24 - slurry supply system. Detailed Embodiments

[0017] The following further describes the present invention with reference to embodiments, but the present invention is not limited in any way. Any transformation or replacement based on the teachings of the present invention falls within the protection scope of the present invention.

[0018] The recyclable induced crystallization agent described in the present invention is composed of a water - soluble binder, a thickener, Fe3O4 powder, activated carbon powder, and induced crystallization material powder.

[0019] The mass ratio of the water - soluble binder, thickener, Fe3O4 powder, activated carbon powder, and induced crystallization material powder is (4 - 6):(0.4 - 0.6):(8 - 12):(4 - 6):(10 - 20).

[0020] The water - soluble binder is carboxymethyl cellulose.

[0021] The thickener is xanthan gum.

[0022] The induced crystallization material is calcium carbonate.

[0023] The preparation method of the recyclable induced crystallization agent described in the present invention includes a pretreatment step, a colloidal matrix preparation step, and a formulation step, specifically including: A. Pretreatment: Mix the Fe3O4 powder, activated carbon powder, and induced crystallization material powder in the formula ratio, then perform ball milling and sieve through a 400-mesh sieve to obtain material a; B. Preparation of the colloidal matrix: 1) Mix the water-soluble binder and thickener in the formula ratio to obtain material b; 2) Under the condition of high-speed stirring at a rotation speed of 10000 - 12000 r / min, dissolve material b in deionized water 10 - 15 times the mass of material b and stir for 15 - 25 min to obtain the colloidal matrix c; C. Formulation: Under the condition of high-speed stirring at a rotation speed of 10000 - 12000 r / min, add material a to the colloidal matrix c and continue stirring for 10 - 30 min to obtain the induced crystallization slurry, that is, the target recyclable induced crystallization agent.

[0024] The application of the present invention is the application of the recyclable induced crystallization agent in an electrochemical hardening removal system with a self-cleaning function.

[0025] The electrochemical hardening removal system with a self-cleaning function includes an electrochemical hardening removal device 1, a magnetic separation system 2, a hydrocyclone 3, an electrocoagulation system 4, and a material recovery system 5. The electrochemical hardening removal device 1, the magnetic separation system 2, the electrocoagulation system 3, and the hydrocyclone 3 are connected in sequence. Both the electrochemical hardening removal device 1 and the magnetic separation system 2 are connected to the material recovery system 5. The electrocoagulation system 4 is connected to a water outlet pipe 10. The electrochemical hardening removal device 1 includes an electrolytic cell 6. The electrolytic cell 6 includes an anode plate 12, a cathode plate 13, and a plate power supply 14. The cathode plate 13 is a copper-nickel alloy electrode plate or a stainless steel electrode plate, and the anode plate 12 is a titanium-based coated anode plate 12. The anode plate 12 and the cathode plate 13 are respectively connected to the positive and negative poles of the power supply, and current is passed through. Water is electrolyzed on the surface of the cathode and the surface of the induced crystallization slurry 9. Under the action of the induced crystallization slurry 9 (hereinafter referred to as the slurry), Ca 2+ / Mg 2+Scaling on the convex surface; the cathode plate 13 is connected to the slurry supply system 24 through a pipeline. The cathode plate 13 is a hollow porous cathode plate. The hollow porous cathode plate is hollow inside and has micropores 16 uniformly distributed on the surface. The aperture of the micropores 16 is 0.1 mm to 1 mm, and the aperture of the micropores 16 increases sequentially from top to bottom. Such a setting can enable the slurry inside the cathode plate 13 to flow out smoothly and avoid the accumulation and blockage of the slurry; a slag discharge port 15 is opened at the bottom of the electrolytic cell 6. The slag discharge port 15 is overall conical, and the slag discharge port 15 is connected to the material recovery system 5 through a pipeline; a water outlet pipe 8 and a water inlet pipe 7 are respectively communicated above and below one side of the electrolytic cell 6. The water outlet pipe 8 is connected to the magnetic separation system 2, and the water inlet pipe 7 is connected to a CO2 intelligent addition system 11; larger particles of sediment accumulate at the bottom of the electrochemical hardening removal device 1 and are discharged through the slag discharge port 15. The magnetic separation system 2 separates the tiny magnetic sediment, and the hydrocyclone 3 and the electrocoagulation system 4 quickly separate the non-magnetic tiny sediment. The wastewater after sediment separation is discharged from the water outlet pipeline 10; the large particles and magnetic sediment are dried, ground, and screened by the material recovery system 5 and then recycled as raw materials for the induced crystallization slurry 9.

[0026] The slurry supply system 14 includes a storage bin 17 and a constant pressure pump 18. The storage bin 17 is filled with the induced crystallization slurry 9, which is mechanically stirred and mixed by deionized water, a water-soluble binder, a thickening agent, Fe3O4 powder, activated carbon powder, and induced crystallization material powder. The slurry supply system 24 injects the slurry into the cavity of the cathode plate 13 of the electrochemical hardening removal device 1 at a certain pressure, forming a protrusion at the micropores 16 on the cathode surface and flowing out at a certain speed.

[0027] The electrochemical hardening removal device 1 is also connected to an intelligent pressure control system 19. The intelligent pressure control system 19 includes a control cabinet Ⅰ 20 and an online hardness monitor 21. The constant pressure pump 18 is installed on the pipeline connecting the slurry supply system 24 and the cathode plate 13, and the online hardness monitor 21 is installed on the water inlet pipe 7 and transmits signals to the control cabinet Ⅰ 20; the online hardness monitor 21 monitors the incoming water hardness in real time and feeds it back to the control cabinet Ⅰ. The control cabinet Ⅰ dynamically adjusts the pressure of the constant pressure pump 18 to control the slurry outflow speed.

[0028] The CO2 intelligent addition system 11 includes a control cabinet Ⅱ 23 and an online pH monitor 22. The online pH monitor 22 is arranged inside the electrolytic cell 6. The online pH monitor 22 is electrically connected to the control cabinet Ⅱ 23, and the control cabinet Ⅱ 23 is connected to the water inlet pipe 7; the online pH monitor 22 monitors the pH of the effluent in real time and feeds it back to the control cabinet Ⅱ 23. The control cabinet Ⅱ 23 dynamically adjusts the CO2 injection amount of the water inlet pipe 7 to maintain the HCO3 - / CO3 2- balance.

[0029] Working principle First, the slurry supply system 24 injects slurry into the cavity of the cathode plate 13 of the electrochemical hardening removal device 1 at a certain pressure, forming a bulge at the micropores 16 on the surface of the cathode plate 13 and flowing out at a certain speed. Then, an electric current is applied, and water is electrolyzed on the surface of the cathode plate 13 and the surface of the slurry. Under the action of the induced crystallization material, Ca 2+ / Mg 2+ scales on the surface of the bulge. As the slurry flows out and more scales form on the surface, the binder gradually dissolves, causing the strength of the slurry to decrease. Under the action of gravity and the scouring of water flow, the slurry and the scales fall off from the surface of the cathode plate 13, achieving the purpose of self-cleaning. Larger particles precipitate and accumulate at the bottom of the electrochemical hardening removal device 1 and are discharged through the slag discharge port 15. The magnetic separation system 2 separates the tiny magnetic precipitates, and the electrocoagulation system 3 and the hydrocyclone separator 4 quickly separate the non-magnetic tiny precipitates. The wastewater after precipitation separation is discharged from the water outlet pipe 10. The large particles and magnetic precipitates are dried, ground, and screened by the material recovery system 5 and then recycled as raw materials for the induced crystallization slurry 9.

[0030] It should be noted that the induced crystallization slurry 9 is mechanically stirred and mixed from deionized water, water-soluble binder, thickener, Fe3O4 powder, activated carbon powder, and induced crystallization material powder. The water-soluble binder gives the slurry certain water solubility and viscosity. The thickener further enhances the viscosity of the slurry and can maintain a certain strength under the scouring of water flow. The Fe3O4 powder makes the slurry magnetic and conductive. The induced crystallization material powder makes the scale tend to form on the surface of the slurry, avoiding scaling on the surface of the cathode plate 13. The activated carbon powder can further enhance the conductivity and induced crystallization performance of the slurry and can adsorb some other pollutants in the wastewater, such as heavy metals and organic substances. During the hardening removal process, under the action of pressure, water flow, and gravity, the slurry keeps flowing out parallel and continuously. Scaling gradually occurs on the surface of the slurry. At the same time, the gradual dissolution of the water-soluble binder and the thickener causes the strength of the mixed slurry to gradually decrease. Finally, under the action of gravity and the scouring of water flow, the mixed slurry and the surface scaling fall off by themselves, achieving the purpose of self-cleaning. At the same time, water flows in from the lower part of the cathode plate 13 and flows out from the upper part. Driven by the water flow, it can avoid the diffusion of OH - generated at the cathode to the anode, improving the hardening removal efficiency. Since the shed precipitate contains the induced crystallization slurry 9 and the generated scale can be used as the induced crystallization material, it can be recycled as the raw material of the induced crystallization slurry 9 through treatment.

[0031] The following further illustrates the present invention with specific embodiments: Example 1

[0032] Components: deionized water (60%), water-soluble binder (carboxymethyl cellulose, 5%), thickener (xanthan gum, 0.5%), Fe3O4 powder (10%), activated carbon powder (5%), crystallization-inducing material (CaCO3 powder, 15%), and the ratios are in mass percentages.

[0033] Process: (1) Add 10 g of Fe3O4 powder, 5 g of activated carbon powder, and 15 g of calcium carbonate powder into a ball mill, ball mill for 1.5 h, and after ball milling, pass through a 400-mesh sieve to obtain a mixed powder.

[0034] (2) Under the condition of a high-speed stirrer speed of 11000 r / min, dissolve 5 g of carboxymethyl cellulose and 0.5 g of xanthan gum in 60 g of deionized water at a temperature of 50 °C, and keep stirring for 20 min to form a colloidal matrix.

[0035] (3) Under the condition of a high-speed stirrer speed of 11000 r / min, slowly add the mixed powder from step (1) into the colloidal matrix from step (2), and continue stirring for 20 min to form a crystallization-inducing slurry, which is the crystallization-inducing agent that can be recycled for the target product.

[0036] Example 2

[0037] Components: deionized water (70%), water-soluble binder (carboxymethyl cellulose, 4%), thickener (xanthan gum, 0.4%), Fe3O4 powder (8%), activated carbon powder (4%), crystallization-inducing material (CaCO3 powder, 13.6%), and the ratios are in mass percentages.

[0038] Process: (1) Add 8 g of Fe3O4 powder, 4 g of activated carbon powder, and 13.6 g of calcium carbonate powder into a ball mill, ball mill for 2 h, and after ball milling, pass through a 400-mesh sieve to obtain a mixed powder.

[0039] (2) Under the condition of a high-speed stirrer speed of 12000 r / min, dissolve 4 g of carboxymethyl cellulose and 0.4 g of xanthan gum in 70 g of deionized water at a temperature of 55 °C, and keep stirring for 12 min to form a colloidal matrix.

[0040] (3) Under the condition of a high-speed stirrer speed of 12000 r / min, slowly add the mixed powder from step (1) into the colloidal matrix from step (2), and continue stirring for 30 min to form a crystallization-inducing slurry, which is the crystallization-inducing agent that can be recycled for the target product.

[0041] Example 3

[0042] Components: Deionized water (58%), water-soluble binder (carboxymethyl cellulose, 6%), thickening agent (xanthan gum, 0.6%), Fe3O4 powder (12%), activated carbon powder (6%), crystallization-inducing material (CaCO3 powder, 17.4%), with the ratio being mass percentage.

[0043] Process: (1) Add 12 g of Fe3O4 powder, 6 g of activated carbon powder, and 17.4 g of calcium carbonate powder into a ball mill, ball mill for 1.8 h, and after ball milling, pass through a 400-mesh sieve to obtain a mixed powder.

[0044] (2) Under the condition that the rotational speed of a high-speed stirrer is 10,000 r / min, dissolve 6 g of carboxymethyl cellulose and 0.6 g of xanthan gum in 58 g of deionized water at a temperature of 45 °C, and keep stirring for 30 min to form a colloidal matrix.

[0045] (3) Under the condition that the rotational speed of a high-speed stirrer is 10,000 r / min, slowly add the mixed powder in step (1) into the colloidal matrix in step (2), and continue stirring for 30 min to form a crystallization-inducing slurry, that is, the crystallization-inducing agent that can be recycled for the target object.

[0046] Example 4

[0047] Perform tests with the crystallization-inducing agent that can be recycled prepared in Example 1, and the test results are as follows: The total hardness of the circulating cooling water of an enterprise is about 600 mg / L. The electrochemical hardening removal device and system of the present invention are used for treatment. The slurry used is prepared according to Example 1, and the equipment operation parameters are shown in Table 1. It runs continuously for 5 months, and the changes in the hardness of the effluent at each time point are shown in Table 2.

[0048] Table 1 Equipment operation parameters

[0049] Table 2 Changes in the hardness of the effluent at each time point

[0050] Example 5

[0051] Perform tests with the crystallization-inducing agents that can be recycled prepared in Example 2 and Example 3 respectively. The method is the same as that in Example 4. The results show that the present invention has the advantages of high efficiency, long-term operation, and is applicable to the large-scale treatment of industrial high-hard wastewater.

Claims

1. A recyclable induced crystallization agent, characterized in that, The recyclable induced crystallization agent is composed of a water-soluble binder, a thickener, Fe3O4 powder, activated carbon powder, and induced crystallization material powder.

2. The recyclable induced crystallization agent according to claim 1, wherein The mass ratio of the water-soluble binder, thickener, Fe3O4 powder, activated carbon powder, and induced crystallization material powder is (4-6):(0.4-0.6):(8-12):(4-6):(10-20).

3. The recyclable induced crystallization agent according to claim 1 or 2, characterized in that, The water-soluble binder is carboxymethyl cellulose.

4. The recyclable induced crystallization agent according to claim 1 or 2, characterized in that, The thickener is xanthan gum.

5. The recyclable induced crystallization agent according to claim 1 or 2, characterized in that, The induced crystallization material is calcium carbonate.

6. A preparation method of the recyclable induced crystallization agent according to any one of claims 1 to 5, characterized in that It includes a pretreatment step, a matrix preparation step, and a formulation step, specifically including: A. Pretreatment: Mix the Fe3O4 powder, activated carbon powder, and induced crystallization material powder in the formula ratio, then perform ball milling and pass through a 400-mesh sieve to obtain material a; B. Matrix preparation: 1) Mix the water-soluble binder and thickener in the formula ratio to obtain material b; 2) Under the condition of high-speed stirring at a speed of 10000-12000 r / min, dissolve material b in deionized water 10-15 times the mass of material b and stir for 15-25 min to obtain a colloidal matrix c; C. Formulation: Under the condition of high-speed stirring at a speed of 10000-12000 r / min, add material a to the colloidal matrix c and continue to stir for 10-30 min to obtain an induced crystallization slurry, that is, the target recyclable induced crystallization agent.

7. Use of the recyclable induced crystallization agent according to any one of claims 1 to 5, characterized in that, Application of the recyclable induced crystallization agent in an electrochemical hardening removal system with a self-cleaning function.

8. Use of the recyclable induced crystallization agent according to claim 7, characterized in that, The electrochemical hardening removal system with a self-cleaning function includes an electrochemical hardening removal device (1), a magnetic separation system (2), a hydrocyclone (3), an electrocoagulation system (4), and a material recovery system (5). The electrochemical hardening removal device (1), the magnetic separation system (2), the electrocoagulation system (4), and the hydrocyclone (3) are connected in sequence. The electrochemical hardening removal device (1) and the magnetic separation system (2) are both connected to the material recovery system (5). The electrocoagulation system (4) is connected to a water outlet pipe (10); The electrochemical hardening removal device (1) includes an electrolytic cell (6). The electrolytic cell (6) is connected to a slurry supply system (24). The electrolytic cell (6) is provided with a water inlet pipe (7) and a water outlet pipe (8). The water inlet pipe (7) is connected to a CO2 intelligent addition system (11).

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