A defoaming method and system for alumina slurry decomposition

Abstract

A defoaming method and system for alumina slurry decomposition, through the method and system, primary defoaming is carried out before the slurry enters the first tank, and auxiliary defoaming is carried out for the foam generated by each intermediate tank decomposition, wherein the primary defoaming is due to the fact that the diameter of the inlet of the first and second conical channels is larger than that of the outlet, so that when the slurry passes through the first and second conical channels, the bubbles in the slurry are broken under the action of tensile stress, thus reducing the bubble content in the slurry from the source, reducing the influence of the foam in the subsequent decomposition process, and indirectly reducing the generation of foam in each decomposition tank. Secondly, in the auxiliary defoaming process, the overflow tank can collect the foam slurry corresponding to the decomposition tank, and under the action of the negative pressure adsorber and the extrusion cavity, the foam in the slurry can be adsorbed and extruded and broken in real time, and then discharged into the overflow tank again. This process can adapt to different slurry conditions and ensure the defoaming efficiency, thereby improving the quality of the product.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of alumina production, in particular to a defoaming method and system for alumina slurry decomposition. BACKGROUND

[0002] The production of alumina in the world is mainly based on the Bayer process. After the bauxite is mixed with the circulating mother liquor, ground and heated for reaction and dissolution, the Bayer process dissolution solution is diluted in a dilution tank with red mud washing solution, and then transported to a separation settling tank. After adding a flocculating agent, the sodium aluminate solution separated from the red mud is called crude liquid. The crude liquid is refined and filtered, and the sodium aluminate solution is called refined liquid. The process of seeding and decomposing the sodium aluminate solution to obtain aluminum hydroxide is carried out in a series of decomposition tanks. In the first decomposition tank, aluminum hydroxide seeds are added, and the decomposition slurry is cooled and left for several hours to complete the decomposition. The sodium aluminate solution is in a supersaturated state after cooling. The addition of aluminum hydroxide seeds under supersaturation conditions produces aluminum hydroxide through seed decomposition process. The decomposition of the aluminum hydroxide slurry needs to be separated into liquid and solid. The filtrate after the decomposition of the slurry is called decomposition mother liquor, which is concentrated by evaporation and enters the next cycle, called circulating mother liquor. The aluminum hydroxide seeds precipitated from the sodium aluminate solution need to be filtered to reduce the amount of sodium aluminate solution attached to their surface, otherwise it will affect the decomposition rate and the particle size of aluminum hydroxide. In the process of alumina production, the decomposition process is one of the important processes.

[0003] In the decomposition process, when the sodium aluminate solution accumulates to a certain extent, due to the presence of organic matter in the bauxite and the addition of additives, the organic matter in the bauxite is mainly humic acid, which dissolves in the alkaline solution during dissolution. With the enrichment of organic matter in the system, the temperature gradually decreases during the decomposition process, the crystallization water is taken away by the precipitated aluminum hydroxide, and the solubility of sodium oxalate also causes supersaturation,

[0004] Sodium oxalate precipitates, forming a suspended layer or causing a large amount of foam. Traditional decomposition tank series consist of multiple individual decomposition tanks connected in series. Although there is a certain height difference between each decomposition tank in the design, it is sometimes necessary to introduce a certain amount of compressed air into the decomposition slurry through the feed pipe. At this time, the air mixed in with the slurry will also generate bubbles. At the same time, the solid phase in the foam (scum) of the decomposition tank is mainly aluminum hydroxide with fine particles of sodium oxalate adsorbed. In addition, when the organic matter in the solution is high, solid sodium oxalate is also present in addition to aluminum hydroxide. These solids are adsorbed on the surface of two-phase bubbles to form three-phase foam, which improves the stability of the foam. Secondly, the stronger the hydrophobicity of the solid surface, the easier it is to adsorb onto the surface of the bubbles, and the less likely the liquid in the liquid film is to be discharged, the higher the foam stability. Bubbles in the liquid always rise to the liquid surface, forming a bubble polymer separated by a liquid film composed of a small amount of liquid, which further improves the stability of the foam. Regardless of its form, due to its low specific gravity, foam floats on the surface of the slurry, easily creating false liquid levels and directly affecting production. Therefore, eliminating the impact of foam is crucial for the entire process. Traditional defoaming methods mainly rely on defoaming agents. However, since defoaming agents are chemicals, their organic matter enters the alumina production system after addition, and long-term accumulation is detrimental to normal production. Summary of the Invention

[0005] To address the aforementioned technical deficiencies, the present invention employs primary and auxiliary defoaming methods in its process, which can progressively reduce the foam generated in each decomposition tank, thereby improving production efficiency and output.

[0006] The present invention adopts the following technical solution:

[0007] A defoaming method for decomposing alumina slurry includes the following steps:

[0008] S1: Obtain semen. After the semen obtained by the Bayer process is cooled by a plate heat exchanger, it is mixed with seed crystals and then pumped into a high-level tank for decomposition by a seed crystal pump.

[0009] S2: First tank decomposition, the slurry stabilized by decomposition in the high tank is sent to the first tank for decomposition after primary defoaming;

[0010] S3: Intermediate tank decomposition, the slurry flowing out of the first tank is decomposed step by step through multiple intermediate tanks, and the foam generated by the decomposition of each intermediate tank is defoamed by the overflow tank.

[0011] S4: Secondary tank decomposition and defoaming. After the slurry is decomposed in the last intermediate tank, it is sent to the secondary tank. The foam generated during the secondary tank decomposition process is filtered by a flat plate vacuum filter and then sent to the final tank for decomposition.

[0012] S5: the slurry in the penultimate tank is decomposed, and then is sent to the last tank through a lifting pipe for decomposition, and then is separated by a vertical disc vacuum filter to form a filter cake, and then is washed to be used as a crystal seed or enters a product system.

[0013] Preferably, the defoaming assembly performs the primary defoaming step as follows:

[0014] S100: the slurry in the high tank is pumped out by a vacuum pump and is sent to the front chamber A of the defoaming body through an inlet;

[0015] S101: when the pressure inside the front chamber A is greater than the pressure inside the middle chamber B, the slurry enters the middle chamber B through a first conical passage on the first defoaming plate, and the slurry passing through the first conical passage can crush the foam in the slurry by extrusion;

[0016] S102: when the pressure inside the middle chamber B is greater than the pressure inside the rear chamber C, the slurry in the middle chamber B that has been defoamed by the first stage enters the rear chamber C through a second conical passage on the second defoaming plate, and then enters the first tank through the rear chamber C after the unbroken foam is crushed by extrusion.

[0017] Preferably, in the primary defoaming process, the pressure of the front chamber A of the defoaming body is kept at 0 to -15 kPa, the inlet flow rate of the slurry is 0.8-1.2 m / s, the pressure of the middle chamber B is set to -15 kPa to -50 kPa, the flow rate of the first conical passage is maintained at 12-18 m / s, the pressure of the rear chamber C is set to -50 kPa to +5 kPa, and the flow rate of the second conical passage is maintained at 25-30 m / s.

[0018] Preferably, the auxiliary defoaming is mainly performed by an auxiliary defoaming mechanism on each overflow tank, the auxiliary defoaming mechanism can automatically adjust the height according to the height of the foam slurry in the overflow tank, and can automatically adjust the adsorption force and the defoaming efficiency according to the feedback information of the viscosity sensor and the flow rate sensor.

[0019] Preferably, the application also provides a system for the defoaming method of the alumina slurry decomposition tank, which comprises a plate heat exchanger, a high tank, a first tank, intermediate tanks, a penultimate tank and a last tank, the plate heat exchanger is connected with the high tank, the high tank is connected with the first tank through a defoaming assembly, the first tank is connected with the intermediate tanks through lifting pipes, the intermediate tanks are not less than three and are connected with each other through lifting pipes and overflow tanks, the penultimate tank is connected with the adjacent intermediate tank through a lifting pipe, and the penultimate tank is connected with the last tank through a lifting pipe.

[0020] Preferably, the defoaming assembly comprises a defoaming body, a first defoaming plate and a second defoaming plate, the bottom and top of the defoaming body are respectively provided with an inlet and an outlet, the inside of the defoaming body is sequentially provided with the first defoaming plate and the second defoaming plate from bottom to top, the inside of the defoaming body is divided into a front chamber A, a middle chamber B and a rear chamber C by the first defoaming plate and the second defoaming plate, each chamber is connected with an external pressure sensor and a pressure compensator, a plurality of first tapered channels and second tapered channels are respectively formed in the first defoaming plate and the second defoaming plate, the first tapered channels and the second tapered channels are staggered and corresponded to each other, the surfaces of the first tapered channels and the second tapered channels are attached with titanium nitride coating, two groups of first grooves are formed in the inner wall of the defoaming body, the first defoaming plate and the second defoaming plate are made of silicon carbide ceramic or wear-resistant alloy, and a second groove is formed in the edge of the first defoaming plate and the second defoaming plate, and a limiting plate is movably installed in the second groove.

[0021] Preferably, the overflow tank is further provided with a plurality of auxiliary defoaming mechanisms along the length direction, the auxiliary defoaming mechanism comprises an adjusting support and an extrusion defoaming assembly, and the extrusion defoaming assembly is movably installed on the adjusting support.

[0022] Preferably, the extrusion defoaming assembly comprises a connecting frame, a floating plate, a negative pressure adsorber, a protective cover, an extrusion cavity, a speed regulating motor, a rotating shaft, a connecting arm, a roller, an extrusion pipe, a discharge pipe and a controller, the connecting frame is movably installed between the two adjusting supports, the bottom of the connecting frame is fixed with the floating plate, one side of the floating plate is further fixedly installed with the negative pressure adsorber, the middle of the floating plate is installed with the protective cover, the speed regulating motor, the extrusion cavity and the controller are arranged in the protective cover, the rotating shaft is installed in the extrusion cavity, the rotating shaft is further fixedly connected with the output end of the speed regulating motor, a plurality of connecting arms are circumferentially arranged on the rotating shaft, the end of each connecting arm is further movably installed with a roller, one end of the extrusion pipe is connected with the negative pressure adsorber, the other end of the extrusion pipe extends into the discharge pipe, and the extrusion pipe passes through the extrusion cavity and is located between the inner wall of the extrusion cavity and the roller.

[0023] Preferably, the floating plate is further provided with a viscosity sensor and a flow rate sensor, and the viscosity sensor and the flow rate sensor are signal connected with the controller.

[0024] Preferably, the adsorption end of the negative pressure adsorber is further provided with a plurality of adsorption nozzles, each adsorption nozzle is connected with a conveying pump through a channel, and the output end of the conveying pump is connected with the input end of the extrusion pipe.

[0025] The beneficial effects of the present application are as follows:

[0026] First, before the slurry enters the first tank, it is subjected to primary defoaming by the defoaming assembly. Since the diameter of the inlet of the first and second tapered channels is larger than that of the outlet, the bubbles in the slurry are broken by the tensile stress when the slurry passes through the converging end of the first and second tapered channels under the action of pressure. Thus, the bubble content in the slurry is reduced from the source, thereby reducing the influence of foam on the subsequent decomposition process and indirectly reducing the generation of foam in each decomposition tank. In addition, the first and second defoaming plates can be quickly disassembled and assembled, facilitating regular cleaning. The surfaces of the first and second tapered channels are coated with a titanium nitride wear-resistant coating, effectively improving the wear resistance of the first and second tapered channels and prolonging their service life.

[0027] Second, during the decomposition process, the overflow tank can collect the foamed slurry corresponding to the decomposition tank, and under the action of the negative pressure adsorber and the extrusion cavity, the foam in the slurry can be adsorbed and then broken in the extrusion cavity to form a slurry form. The controller can adaptively adjust the adsorption capacity of the negative pressure adsorber and the speed of the speed-regulating motor according to the viscosity and flow rate of the slurry, thereby adapting to the state of different slurries and discharging the defoamed slurry back into the overflow tank, reducing the influence of the foam in the last tank on the decomposition slurry, thereby ensuring the decomposition efficiency of the last tank and improving the quality of the product. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The method flowchart of the present application;

[0029] Figure 2 The process flowchart of the present application;

[0030] Figure 3 The internal structure diagram of the defoaming assembly;

[0031] Figure 4 The Figure 3 enlarged structure diagram of part E;

[0032] Figure 5 The Figure 3 enlarged structure diagram of part F;

[0033] Figure 6 The structure diagram of the auxiliary defoaming mechanism;

[0034] Figure 7 The Figure 5 enlarged structure diagram of part G;

[0035] In the figure: plate heat exchanger 1, high tank 2, first tank 3, intermediate tank 4, penultimate tank 5, last tank 6, lifting pipe 7, overflow tank 8, flat disc vacuum filter 9, vertical disc vacuum filter 10, defoaming assembly 11, defoaming body 110, first defoaming plate 111, second defoaming plate 112, first-order conical passage 113, second-order conical passage 114, front chamber A, middle chamber B, rear chamber C, auxiliary defoaming mechanism 12, adjusting bracket 120, extrusion defoaming assembly 121, connecting frame 1210, floating plate 1211, negative pressure adsorber 1212, protective cover 1213, extrusion cavity 1214, speed regulating motor 1215, rotating shaft 1216, connecting arm 1217, roller 1218, extrusion pipe 1219, discharge pipe 1220, controller 1221, adsorption nozzle 13, conveying pump 14, first groove 15, second groove 16, limiting plate 17, viscosity sensor 18 and flow rate sensor 19. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0037] In the description of the present application, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the present application, in the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0038] Example one:

[0039] Please refer to Figures 1-2 A defoaming method for alumina slurry decomposition, comprising the following steps:

[0040] S1: obtaining the liquor, mixing the liquor obtained by the Bayer process with the seed crystals after cooling through the plate heat exchanger 1, and pumping into the high tank 2 for decomposition; wherein the high tank 2 mainly plays a stabilizing role, after the slurry is stabilized in the high tank 2, the foam in the subsequent decomposition process can be reduced, and it is ensured that the slurry entering the first tank 3 can be fully decomposed and is not affected by the foam.

[0041] S2: The slurry in the high tank 2 is decomposed and sent to the first tank 3 for decomposition after primary defoaming by the defoaming assembly 11. The primary defoaming reduces the foam from the source, and the principle is to use the pressure difference generated when the foam passes through the micropore to destroy the liquid film. The surface tension of the foam is destroyed by the secondary extrusion, so that when it enters the first tank 3 for decomposition, a large number of bubbles will not be generated.

[0042] S3: The slurry flowing out of the first tank 3 is sequentially decomposed by multiple intermediate tanks 4, and the foam generated by the decomposition of each intermediate tank 4 is collected and then subjected to auxiliary defoaming by the overflow tank 8. The auxiliary defoaming mainly collects the foam generated during the decomposition of each intermediate tank 4 through the overflow tank 8, and then subjects the collected foam to auxiliary defoaming. In this way, the overflow foam of each intermediate tank 4 will not flow into the secondary last tank 5, thereby affecting the decomposition of the secondary last tank 5.

[0043] S4: Decomposition and defoaming of the secondary last tank 5. After the slurry is decomposed by the last intermediate tank 4, it is sent to the secondary last tank 5. The foam generated during the decomposition of the secondary last tank 5 is filtered by the flat disc vacuum filter 9 and then sent to the last tank 6 for decomposition. The foam generated during the decomposition of the secondary last tank 5 is filtered by the flat disc vacuum filter 9, so that the foam will not be brought into the last tank 6, thereby affecting the decomposition efficiency of the last tank 6.

[0044] S5: Decomposition of the last tank 6. The slurry decomposed by the secondary last tank 5 is sent to the last tank 6 through the lifting pipe 7 for decomposition, and then separated by the vertical disc vacuum filter 10 to form a filter cake, which is washed and used as a crystal seed or enters the product system.

[0045] Referring to Figures 3-4 The steps of primary defoaming by the defoaming assembly 11 are as follows:

[0046] S100: The slurry in the high tank 2 is pumped out by a vacuum pump and sent to the front chamber A through the inlet of the defoaming main body 110.

[0047] S101: When the pressure in the front chamber A is greater than the pressure in the middle chamber B, the slurry enters the middle chamber B through the first defoaming plate 111 and the first tapered channel 113. The slurry passing through the first tapered channel 113 will cause the foam in the slurry to be extruded and broken.

[0048] S102: When the pressure in the middle chamber B is greater than the pressure in the rear chamber C, the slurry in the middle chamber B that has been subjected to primary defoaming enters the rear chamber C through the second defoaming plate 112 and the second tapered channel 114, and then enters the first tank 3 after the rear chamber C.

[0049] In the primary defoaming process, the pressure in the three chambers inside the defoaming body 110 is mainly controlled by the external pressure regulator. The pressure regulator can automatically compensate and adjust the pressure in each chamber according to the real-time pressure information of the pressure sensor in each chamber, ensuring that the pressure remains stable during the defoaming process. This avoids the problem of inaccurate pressure control caused by slurry fluctuations, leading to unsatisfactory defoaming.

[0050] The pressure in the front chamber A of the defoaming body 110 needs to be set at 0 to -15 kPa, and the slurry inlet flow rate needs to be maintained at 0.8-1.2 m / s. This ensures that the slurry enters the front chamber A at a certain pressure and speed. The pressure and flow rate of the feed cannot be higher than this range, otherwise new bubbles will be generated. As the slurry enters, the pressure in the middle chamber B is set to -15 kPa to -50 kPa. Due to the pressure difference, the slurry in the front chamber A will pass through the first conical channel at a speed of 12-18 m / s. Due to the conical structure and pressure difference, the bubbles in the slurry are broken. After the middle chamber B is filled with slurry, the slurry passes through the second conical channel at a speed of 25-30 m / s, achieving the second breaking of bubbles in the slurry.

[0051] Specific defoaming working principle:

[0052] First, before starting, the defoaming assembly 11 is at the same pressure. When defoaming is needed, the vacuum pump first sucks out the decomposed and stable slurry in the high tank 2, then controls the slurry to enter the front chamber A at a certain pressure, 0 to -15 kPa, and flow rate, 0.8-1.2 m / s. As the slurry continuously enters, the front chamber A will be filled with slurry. At this time, as the slurry continues to be delivered, the pressure in the front chamber A will gradually be higher than that in the middle chamber B. At this time, the slurry will pass through the first conical channel 113. Since the inlet of the first conical channel 113 is larger than the outlet, the bubbles in the slurry will squeeze each other, causing the bubbles in the slurry to be completely broken. Then, as the slurry in the middle chamber B accumulates, the slurry in the middle chamber B will pass through the second conical channel 114. The defoaming principle is the same as that in the first conical channel 113, further defoaming the unbroken bubbles in the first slurry. This is equivalent to two-stage defoaming, reducing the bubble content in the slurry, and thus reducing the impact of foam in the decomposition process.

[0053] Referring to Figure 5 , the auxiliary defoaming is mainly through the auxiliary defoaming mechanism 12 to defoam each overflow tank 8. The auxiliary defoaming mechanism 12 can automatically adjust the height according to the height of the foam slurry in the overflow tank 8, and can adaptively adjust the adsorption force and defoaming efficiency according to the feedback information of the viscosity sensor 18 and the flow rate sensor 19.

[0054] The application further provides an alumina slurry decomposition defoaming system, which comprises a plate heat exchanger 1, an upper tank 2, a first tank 3, intermediate tanks 4, a penultimate tank 5 and a last tank 6, the plate heat exchanger 1 is connected with the upper tank 2, the upper tank 2 is connected with the first tank 3 through a defoaming assembly 11, the first tank 3 is connected with the intermediate tanks 4 through lifting pipes 7, the intermediate tanks 4 are not less than three and are connected with each other through the lifting pipes 7 and overflow tanks 8, the penultimate tank 5 is connected with the adjacent intermediate tank 4 through the lifting pipe 7, and the penultimate tank 5 is connected with the last tank 6 through the lifting pipe 7. Through the above technical scheme, the concentrate is mixed with the crystal seeds after being cooled in the plate heat exchanger 1, is stably decomposed in the upper tank 2, is crushed by the secondary micro-hole extrusion of the defoaming assembly 11, so that the content of the bubbles in the slurry is reduced, the carbonization decomposition of the subsequent slurry is ensured, the bubbles generated by the decomposition of the first tank 3 and each intermediate tank 4 are defoamed separately through the auxiliary defoaming mechanism 12 on the overflow tank 8, are finally concentrated in the penultimate tank 5 and are filtered through the flat disc vacuum filter 9, and are continuously decomposed through the last tank 6. The decomposition efficiency of the last tank 6 is maximized because the last tank 6 does not accumulate the bubbles of the upper stage, and the bubbles generated by the decomposition of the last tank 6 are filtered under the action of the vertical disc vacuum filter 10, are evaporated into circulating mother liquor, and the fine particles in the bubbles and the aluminum hydroxide form filter cake together, are washed and returned to the decomposition first tank as crystal seeds or are put into a product system.

[0055] Referring to Figures 3-5The defoaming assembly 11 comprises a defoaming body 110, a first defoaming plate 111 and a second defoaming plate 112, the bottom and top of the defoaming body 110 are respectively provided with an inlet and an outlet, the stabilized slurry enters the front chamber A through the inlet, the first defoaming plate 111 and the second defoaming plate 112 are sequentially arranged inside the defoaming body 110 from bottom to top, the inside of the defoaming body 110 is divided into the front chamber A, the middle chamber B and the rear chamber C by the first defoaming plate 111 and the second defoaming plate 112, each chamber is connected with an external pressure sensor and a pressure compensator, and a plurality of first tapered channels 113 and second tapered channels 114 are respectively arranged on the first defoaming plate 111 and the second defoaming plate 112, and the first tapered channels 113 and the second tapered channels 114 correspond to each other in interlacing mode. The diameter of the inlet of the first tapered channel 113 and the second tapered channel 114 is greater than that of the outlet, so that the bubbles in the slurry are broken under the action of tensile stress when the slurry passes through the contraction end of the first tapered channel 113 and the second tapered channel 114 under the action of pressure, thus reducing the bubble content in the slurry from the source and reducing the formation of foam on the surface of the slurry. The surfaces of the first tapered channel 113 and the second tapered channel 114 are coated with a titanium nitride coating, which can avoid wear of the first tapered channel 113 and the second tapered channel 114. The inner wall of the defoaming body 110 is also provided with two groups of first grooves 15, the first defoaming plate 111 and the second defoaming plate 112 are made of silicon carbide ceramic or wear-resistant alloy, and the upper edges of the first defoaming plate 111 and the second defoaming plate 112 are respectively provided with second grooves 16, and the second grooves 16 are movably provided with limiting plates 17. The first grooves 15 and the second grooves 15 can cooperate with each other to limit the first defoaming plate 111 and the second defoaming plate 112, that is, when disassembly is needed, only the outer top rod is inserted to compress the spring in the second groove 16 to remove the first defoaming plate 111 and the second defoaming plate 112, which facilitates cleaning of the first tapered channel 113 and the second tapered channel 114, prevents blockage and reduces defoaming efficiency, and modular assembly and disassembly improve work efficiency.

[0056] Referring to Figures 5-7, the overflow tank 8 is also provided with several auxiliary defoaming mechanisms 12 along the length direction, the auxiliary defoaming mechanisms 12 are installed at intervals, so that the defoaming efficiency of the foam can be improved, secondly, a centrifugal separator or a filter screen can be arranged at the front end position of each overflow tank 8, the centrifugal separator and the filter screen can remove the solid particles in the slurry, avoid the influence of the solid on the auxiliary defoaming mechanism 12, and ensure the working efficiency of the subsequent auxiliary defoaming mechanism 12, the auxiliary defoaming mechanism 12 comprises an adjusting support 120 and an extrusion defoaming assembly 121, and the extrusion defoaming assembly 121 is movably installed on the adjusting support 120, wherein the adjusting support 120 can be automatically adjusted up and down mainly according to the liquid level of the slurry in the overflow tank 8, and the principle is that the material density of the floating plate 1211 is less than that of the slurry, so that the floating plate 1211 will change with the liquid level of the slurry.

[0057] The extrusion defoaming assembly 121 comprises a connecting frame 1210, a floating plate 1211, a negative pressure adsorber 1212, a protective cover 1213, an extrusion cavity 1214, a speed regulating motor 1215, a rotating shaft 1216, a connecting arm 1217, a roller 1218, an extrusion pipe 1219, a discharge pipe 1220 and a controller 1221, the connecting frame 1210 is movably installed between the two adjusting supports 120, the top of the connecting frame 1210 is movably installed on the adjusting support 120 through a rotating shaft, the bottom of the connecting frame 1210 is fixed with the floating plate 1211, the floating plate 1211 is generally of a hollow ceramic material, which can float on the slurry, thereby improving the stability, one side of the floating plate 1211 is also fixedly installed with the negative pressure adsorber 1212, the negative pressure adsorber 1212 mainly adsorbs the foam on the surface of the slurry, and sends the adsorbed foam into the extrusion cavity 1214 through the extrusion pipe 1219, so that the foam can be broken and returned to the slurry in the overflow tank 8, the protective cover 1213 is installed in the middle of the floating plate 1211, the speed regulating motor 1215, the extrusion cavity 1214 and the controller 1221 are arranged in the protective cover 1213, the controller 1221 is also signal connected with the speed regulating motor 1215, the rotating shaft 1216 is installed in the extrusion cavity 1214, the rotating shaft 1216 is fixedly connected with the output end of the speed regulating motor 1215, a plurality of connecting arms 1217 are arranged on the circumference of the rotating shaft 1216, the end of each connecting arm 1217 is movably installed with a roller 1218, one end of the extrusion pipe 1219 is connected with the negative pressure adsorber 1212, the other end extends into the discharge pipe 1220, and the extrusion pipe 1219 passes through the extrusion cavity 1214 and is located between the inner wall of the extrusion cavity 1214 and the roller 1218.

[0058] The floating plate 1211 is also provided with a viscosity sensor 18 and a flow rate sensor 19, and the viscosity sensor 18 and the flow rate sensor 19 are both in signal connection with the controller 1221, wherein the viscosity sensor 18 and the flow rate sensor 19 can monitor the flow rate and viscosity of the slurry in the overflow tank 8 in real time, and when the viscosity and flow rate change, the signal can be transmitted to the controller 1221 in real time, and the controller 1221 can change the adsorption capacity of the negative pressure adsorber 1212 and the rotating speed of the speed regulating motor 1215 in real time, so as to ensure the defoaming rate of the foam. The defoaming data of the irradiation defoaming mechanism 12 on different viscosity slurry and flow rate slurry are shown in the table.

[0059]

[0060] According to the actual data, the controller 1221 can automatically adjust the adsorption capacity and defoaming efficiency according to the feedback information of the viscosity sensor 18 and the flow rate sensor 19, which replaces the traditional method of defoaming by using defoaming agent.

[0061] The adsorption end of the negative pressure adsorber 1212 is also provided with a plurality of adsorption nozzles 13, each adsorption nozzle 13 is wrapped with a polytetrafluoroethylene cleaning coating, so that the foam is not easy to accumulate on the adsorption nozzle 13, and the adsorption nozzle 13 is not corroded and blocked, and each adsorption nozzle 13 is connected with the delivery pump 14 through a channel, and the output end of the delivery pump 14 is connected with the input end of the extrusion pipe 1219.

[0062] Extrusion defoaming principle:

[0063] Firstly, the negative pressure adsorber 1212 sucks the foam in the slurry through the adsorption nozzle 13 by negative pressure, and each adsorption nozzle 13 sends the foam into the delivery pump 14 through the corresponding channel, and under the action of the delivery pump 14, the foam is delivered into the extrusion cavity 1214 through the extrusion pipe 1219. In this process, the speed regulating motor 1216 is started to drive the rotating shaft 1216 to rotate in the extrusion cavity 1214, and the connecting arm 1217 rotates synchronously in the rotating process. Since the other end of each connecting arm 1217 is movably connected with the roller 1218, the roller 1218 will constantly press the extrusion pipe 1219 in the rotating process, so that the foam in the extrusion pipe 1219 is broken, and the foam can also be discharged from the extrusion pipe 1219 in the rotating process. There is no gas bubble in the discharged liquid, and the liquid is returned to the slurry through the discharge pipe 1220.

[0064] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application in other forms. Any skilled person in the art can modify or change the disclosed technical content into equivalent embodiments with equivalent changes, and apply them to other fields. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, without departing from the technical solution content of the present application, still falls within the protection scope of the present application.

Claims

1. A defoaming method for the decomposition of an alumina slurry, characterized in that, It comprises the following steps: S1: obtaining semen, mixing the semen obtained by Bayer method with seed after cooling through plate heat exchanger (1), and pumping into high tank (2) for decomposition; S2: first tank (3) decomposition, after primary defoaming, the slurry in high tank (2) is sent into first tank (3) for decomposition, the steps of primary defoaming are as follows: S100: the slurry in high tank (2) is pumped out by vacuum pump and sent into front chamber A through the inlet of defoaming main body (110); S101: when the pressure inside front chamber A is greater than that of middle chamber B, the slurry will enter middle chamber B through the first defoaming plate (111) on the first conical channel (113), and the slurry will be crushed by the foam in the slurry through the first conical channel (113); S102: when the pressure inside middle chamber B is greater than that of rear chamber C, the slurry in middle chamber B after primary defoaming will enter rear chamber C through the second conical channel (114) on the second defoaming plate (112) to further crush the unbroken foam, and finally enter first tank (3) through rear chamber C; S3: the intermediate tank (4) is decomposed, the slurry flowing out of the first tank (3) is sequentially decomposed through multiple intermediate tanks (4) in stages, the foam generated by each intermediate tank (4) is assisted defoaming through the overflow tank (8), the overflow tank (8) is also provided with a plurality of auxiliary defoaming mechanisms (12) along the length direction, the auxiliary defoaming mechanism (12) comprises an adjusting support (120) and a squeezing defoaming assembly (121), the squeezing defoaming assembly (121) is movably installed on the adjusting support (120), the squeezing defoaming assembly (121) comprises a connecting frame (1210), a floating plate (1211), a negative pressure adsorber (1212), a protective cover (1213), a squeezing cavity (1214), a speed regulating motor (1215), a rotating shaft (1216), a connecting arm (1217), a roller (1218), a squeezing pipe (1219), a discharge pipe (1220) and a controller (1221), the connecting frame (1210) is movably installed between two adjusting supports (120), the bottom of the connecting frame (1210) is fixed with the floating plate (1211), one side of the floating plate (1211) is also fixedly installed with the negative pressure adsorber (1212), the middle of the floating plate (1211) is installed with the protective cover (1213), the speed regulating motor (1215), the squeezing cavity (1214) and the controller (1221) are arranged in the protective cover (1213), the rotating shaft (1216) is installed in the squeezing cavity (1214), the rotating shaft (1216) is also fixedly connected with the output end of the speed regulating motor (1215), a plurality of connecting arms (1217) are circumferentially arranged on the rotating shaft (1216), the end of each connecting arm (1217) is movably installed with the roller (1218), one end of the squeezing pipe (1219) is connected with the negative pressure adsorber (1212), the other end of the squeezing pipe (1219) extends into the discharge pipe (1220), and the squeezing pipe (1219) passes through the squeezing cavity (1214) and is located between the inner wall of the squeezing cavity (1214) and the roller (1218); S4: the secondary last tank (5) is decomposed and defoamed, after the slurry is decomposed through the last intermediate tank (4), the slurry is sent to the secondary last tank (5), the foam generated in the decomposition process of the secondary last tank (5) is filtered through the flat disc vacuum filter (9) and then sent to the last tank (6) for decomposition; S5: the last tank (6) is decomposed, the slurry decomposed by the secondary last tank (5) is sent to the last tank (6) through the lifting pipe (7) for decomposition, and after the decomposition, the slurry is separated through the vertical disc vacuum filter (10) to form a filter cake, which is washed and used as a crystal seed or enters a product system.

2. The defoaming method for alumina slurry decomposition according to claim 1, characterized by, In the primary defoaming process, the pressure of the front chamber A of the defoaming main body (110) needs to be kept at 0 to -15 kPa, the slurry inlet flow rate is 0.8-1.2 m / s; the pressure of the middle chamber B is set to -15 kPa to -50 kPa, the flow rate of the first conical channel (113) is maintained at 12-18 m / s; the pressure of the rear chamber C is set to -50 kPa to +5 kPa, and the flow rate of the second conical channel (114) is maintained at 25-30 m / s.

3. The defoaming method for alumina slurry decomposition according to claim 1, characterized by, The auxiliary defoaming mainly defoams each overflow tank (8) through the auxiliary defoaming mechanism (12), the auxiliary defoaming mechanism (12) can adjust the height according to the height of the foam slurry in the overflow tank (8), and can adaptively adjust the adsorption force and the defoaming efficiency according to the feedback information of the viscosity sensor (18) and the flow rate sensor (19).

4. A method for defoaming an alumina slurry decomposition according to claim 1, characterized in that, The viscosity sensor (18) and the flow rate sensor (19) are further arranged on the floating plate (1211), and the viscosity sensor (18) and the flow rate sensor (19) are signal connected with the controller (1221).

5. A method for defoaming an alumina slurry decomposition according to claim 1, characterized in that, The adsorption end of the negative pressure adsorber (1212) is further provided with a plurality of adsorption nozzles (13), and each adsorption nozzle (13) is connected with a conveying pump (14) through a channel, and the output end of the conveying pump (14) is connected with the input end of the extrusion pipe (1219).

6. A defoaming system for the decomposition of an alumina slurry for carrying out the defoaming method for the decomposition of an alumina slurry according to any one of claims 1 to 5, characterized in that The plate heat exchanger (1), the high tank (2), the first tank (3), the intermediate tank (4), the second last tank (5) and the last tank (6) are connected, the plate heat exchanger (1) is connected with the high tank (2), the high tank (2) is connected with the first tank (3) through the defoaming assembly (11), the first tank (3) is connected with the intermediate tank (4) through the lifting pipe (7), the intermediate tank (4) is not less than three, and is also connected with each other through the lifting pipe (7) and the overflow tank (8), the second last tank (5) is also connected with the adjacent intermediate tank (4) through the lifting pipe (7), and the second last tank (5) is also connected with the last tank (6) through the lifting pipe (7).

7. The defoaming system for alumina slurry decomposition according to claim 6, characterized in that, The defoaming assembly (11) comprises a defoaming body (110), a first defoaming plate (111) and a second defoaming plate (112), the bottom and the top of the defoaming body (110) are respectively provided with an inlet and an outlet, the first defoaming plate (111) and the second defoaming plate (112) are sequentially arranged inside the defoaming body (110) from bottom to top, the inside of the defoaming body (110) is divided into front chamber A, middle chamber B and rear chamber C through the first defoaming plate (111) and the second defoaming plate (112), each chamber is connected with an external pressure sensor and a pressure compensator, a plurality of first tapered channels (113) and second tapered channels (114) are respectively arranged on the first defoaming plate (111) and the second defoaming plate (112), the first tapered channels (113) and the second tapered channels (114) are staggered and corresponded, the surfaces of the first tapered channels (113) and the second tapered channels (114) are attached with titanium nitride coating, two groups of first grooves (15) are arranged on the inner wall of the defoaming body (110), the first defoaming plate (111) and the second defoaming plate (112) are made of silicon carbide, second grooves (16) are arranged on the edges of the first defoaming plate (111) and the second defoaming plate (112), and the second grooves (16) are movably installed with limiting plates (17).

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