Powdery adsorbent lossless recovery process based on belt filter

Abstract

The present invention discloses a belt filter-based powdery adsorbent lossless recovery process, which comprises a first separation step of collecting a powdery adsorbent at the tail end of a belt filter, and in the first separation step, at least a gas-water mixed fluid is adopted to wash a filter cloth so as to separate the powdery adsorbent from the filter cloth. According to the invention, the separation mode of pure water washing adopted in the prior art is abandoned, and the air-water mixed fluid is adopted to wash the filter cloth, so that the separation mode not only can greatly save the use amount of liquid, but also can reduce the water content in the washed powdery adsorbent suspension, greatly reduces the leakage amount of the powdery adsorbent in the transfer process, and improves the transfer efficiency of the powdery adsorbent. The recovery rate of the powdery adsorbent is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a lossless recovery process of a powdered adsorbent based on a belt filter. Background Art

[0002] At present, it is an effective method to treat brine by using a vacuum belt filter (hereinafter referred to as belt filter) in combination with a powdered adsorbent (for example, the Chinese invention patent with publication number CN111825152B discloses a belt filter and its application in lithium extraction from brine by adsorption method). Powdered adsorbent is a key raw material for brine treatment and has a high investment cost. Therefore, it is very important to recover the powdered adsorbent without loss at the end of the belt filter.

[0003] In order to solve this problem, a Chinese invention patent with publication number CN115261639B discloses a lossless recovery process, a lossless recovery device and a lossless circulation system for powdered adsorbent for lithium extraction from brine. The lossless recovery process includes: collecting powdered adsorbent at the tail end of a belt filter; wherein the powdered adsorbent is separated from the belt filter by scraping and washing; the collected powdered adsorbent is transported to a mixed adsorption tank at the head end of the belt filter by a hoist, wherein the powdered adsorbent is separated from the hoist by washing; the hoist is arranged between the tail end of one belt filter and the head end of another belt filter, and the two hoists connect the two belt filters in series.

[0004] It can be seen that the recovery process needs to separate the powdered adsorbent from the filter cloth by water washing. However, in order to fully wash the powdered adsorbent off the filter cloth, the water flow rate is usually large; this not only wastes a large amount of washing liquid, but also causes the water content of the adsorbent on the elevator to be too high, which is not conducive to lifting on a larger slope; it also causes a lot of adsorbent to be lost, with a large amount of leakage. Summary of the invention

[0005] The object of the present invention is to provide a non-destructive recovery process of powdered adsorbent based on a belt filter, so as to reduce the loss of powdered adsorbent during the recovery process.

[0006] To achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows: A non-destructive recovery process for powdered adsorbent based on a belt filter, the non-destructive recovery process comprising a first separation step of collecting the powdered adsorbent at the tail end of the belt filter, in which at least a gas-water mixed fluid is used to flush the filter cloth to separate the powdered adsorbent from the filter cloth.

[0007] The present invention abandons the simple water washing separation method used in the prior art, and instead adopts an air-water mixed fluid to wash the filter cloth. This separation method can not only greatly save the amount of liquid used, but also reduce the water content in the washed powdered adsorbent suspension, greatly reduce the leakage of the powdered adsorbent during the transportation process, and improve the recovery rate of the powdered adsorbent.

[0008] Preferably, the above-mentioned method for lossless recovery of powdered adsorbent utilizes an air-water mixture unloader to apply an air-water mixture fluid to the filter cloth, and the air-water mixture unloader comprises at least one application pipe, and the application pipe is arranged on the rotation path of the filter cloth and is located on the inner side of the filter cloth, and the application pipe is provided with a plurality of application holes for spraying the air-water mixture fluid to the filter cloth.

[0009] Flushing from the inside can promote the rapid separation of the powdered adsorbent from the filter cloth. The gas-water mixed fluid sprayed from the application hole can be sprayed intermittently or continuously. The present invention has no special requirements for this, depending on the distribution of the powdered adsorbent on the filter cloth. When the intermittent spraying method is adopted, the spraying area can also be ensured by setting up several application pipes.

[0010] In the present invention, the application pipe can be arranged in a state close to or close to the filter cloth, or in a state where the filter cloth is stretched; in the state where the filter cloth is stretched, the filter cloth can be washed while changing the running direction (giving the powdered adsorbent a certain peeling force), so the separation effect is better.

[0011] Preferably, in the above-mentioned method for lossless recovery of powdered adsorbent, the gas flow rate in the gas-water mixed fluid is 0.2-0.5 m³ / h, and the liquid flow rate is 0.8-2.0 m³ / h; more preferably, the gas flow rate is 0.3-0.5 m³ / h, and the liquid flow rate is 1-1.5 m³ / h. Under this fluid flow rate, the adsorbent recovery rate can reach more than 99%. The method for lossless recovery of powdered adsorbent of the present invention has no special requirements on the type of gas used in the gas-water mixed fluid. Any gas can be used in the present invention. Compressed air is more preferred because of its relatively low cost. The liquid used can be a stock liquid (i.e., the brine stock liquid to be treated by the belt filter) or a desorption liquid (i.e., the desorption liquid used by the belt filter in the desorption stage). The stock liquid is more preferred, so that the powdered adsorbent suspension left on the filter cloth has a consistent composition when it is returned to the head end of the belt filter for reuse.

[0012] Preferably, the non-destructive recovery method of powdered adsorbent of the present invention further comprises: a lifting step of using a lifter to transport the collected powdered adsorbent to the head end of the same belt filter. Preferably, in the above-mentioned non-destructive recovery method of powdered adsorbent, the lifter comprises a frame and a conveyor belt circulated on the frame; The conveyor belt includes a return section located below the belt filter, a reuse section located above the head end of the belt filter, and a lifting section connecting the return section and the reuse section; The running direction of the return section is consistent with the rotating direction of the filter cloth, and the running direction of the reuse section is consistent with the advancing direction of the filter cloth.

[0013] In the present invention, the elevator is semi-enclosed and arranged on the outer periphery of the belt filter, which not only has a compact structure and a small footprint, but also can realize the recycling of the adsorbent of a single belt filter.

[0014] As a further preference, in the above-mentioned method for lossless recovery of powdered adsorbent, the surface of the conveyor belt is provided with a plurality of material blocking members arranged in sequence along the running direction of the conveyor belt, and a material accumulation trough is formed between the material blocking members and the conveyor belt, and the angle between the material blocking members and the conveyor belt is 30-60°.

[0015] As a further preference, in the above-mentioned method for lossless recovery of powdered adsorbent, the running speed of the filter cloth is 0.5-3 m / min, and the running speed of the conveyor belt is greater than 5 m / min. The suitable running speed of the filter cloth is to avoid water flow between the various sections (solid-liquid separation zone, smoking zone and desorption zone) of the belt filter, and the higher running speed of the conveyor belt can improve the adsorbent recovery efficiency.

[0016] Preferably, the above-mentioned method for lossless recovery of powdered adsorbent further comprises a second separation step of separating the powdered adsorbent from the elevator; In the second separation step, liquid or a gas-water mixed fluid is used to wash the conveyor belt of the elevator.

[0017] As a further preference, in the above-mentioned method for lossless recovery of powdered adsorbent, at the head end of the belt filter, the frame is provided with a collecting hopper for receiving the powdered adsorbent from the recycling section; the top opening width of the collecting hopper is equivalent to the length of the recycling section, and the collecting hopper is provided with a flushing pipe for flushing the powdered adsorbent from the recycling section and / or the collecting hopper.

[0018] In this way, once the powdered adsorbent suspension is transferred from the lifting section to the recycling section, the powdered adsorbent suspension will be collected by the collecting hopper and will not flow down randomly; the residue on the conveyor belt and / or the collecting hopper is washed by the flushing pipeline. The flushing fluid used in the flushing pipeline can be a liquid (such as a stock solution) or a gas-water mixed fluid, and the present invention has no requirements for this.

[0019] It should be noted that since there are material stops on the surface of the conveyor belt, more attention should be paid to the flushing angle of the flushing pipe, that is, the flushing direction of at least one flushing pipe should be opposite to the running direction of the conveyor belt to flush the material trough as much as possible.

[0020] Compared with the prior art, the technical effects of the present invention are embodied in: (1) The present invention abandons the separation method of simple water washing used in the prior art, and instead adopts a gas-water mixed fluid to wash the filter cloth. This separation method can not only greatly save the amount of liquid used, but also reduce the water content in the washed powdered adsorbent suspension, greatly reduce the leakage of the powdered adsorbent during the transportation process, and improve the recovery rate of the powdered adsorbent.

[0021] (2) The present invention arranges the feeding pipe of the gas-water mixing discharger on the rotation path of the filter cloth and on the inner side of the filter cloth. Flushing from the inner side can promote the rapid separation of the powdered adsorbent from the filter cloth. At the same time, the feeding pipe can be close to or close to the filter cloth, or it can be tensioned. When the filter cloth is tensioned, the filter cloth can be flushed while changing the running direction (giving the powdered adsorbent a certain peeling force), so the separation effect is better.

[0022] In the present invention, the elevator is semi-enclosed and arranged on the outer periphery of the belt filter, which not only has a compact structure and a small footprint, but also can realize the recycling of the adsorbent of a single belt filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the equipment used in the non-destructive recovery process of powdered adsorbent based on a belt filter of the present invention; Figure 2 It is a schematic structural diagram of the equipment used in the non-destructive recovery process of powdered adsorbent based on a belt filter according to the present invention from another perspective; Figure 3 It is a schematic structural diagram of the equipment used in the non-destructive recovery process of powdered adsorbent based on a belt filter according to the present invention from another perspective; Figure 4 for Figure 3 A magnified view of part A; Figure 5 for Figure 1 Schematic diagram of the structure of the middle hoist; Figure 6 for Figure 5 Schematic diagram of the flushing direction of the flushing pipe. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0025] Example 1 This embodiment is a non-destructive recovery process of powdered adsorbent based on a belt filter 1. Figure 1 , Figure 2 and Figure 3 The following steps are performed on the device shown: (1) Collecting powdered adsorbent at the tail end of the belt filter 1; like Figure 4 Shown, combined Figure 2 and Figure 3 It can be seen that an air-water mixed discharger 2 is provided at the tail end of the belt filter 1, and the air-water mixed discharger 2 includes at least one application pipe 21; the filter cloth 11 rotates at the tail end of the belt filter 1, and at least one application pipe 21 is provided at the rotation position of the filter cloth 11 or on the rotation path of the filter cloth 11. These application pipes 21 are located on the inner side of the filter cloth 11, and can be only close to or close to the filter cloth 11, or can directly participate in the tensioning of the filter cloth 11. Each application pipe 21 is provided with a plurality of application holes for spraying an air-water mixed fluid to the filter cloth 11, and the number of application holes is preferably such that the spraying amount can cover the entire width of the filter cloth 11; the air-water mixed fluid sprayed from the application holes can be sprayed intermittently, can be sprayed continuously, or can have both, and this embodiment has no requirements for this.

[0026] In this embodiment, the gas-water mixed fluid is composed of gas and liquid, the gas is air, and the liquid is raw liquid (the same as the raw liquid treated at the head end of the belt filter 1), and the gas and liquid flow rates are shown in Table 1; The washed powdery adsorbent is collected below the belt filter 1 .

[0027] (2) Using an elevator 3 to transport the collected powdered adsorbent to the head end of the same belt filter 1; In order to recover the powdered adsorbent, a hoist 3 is semi-enclosed on the outer periphery of the belt filter 1. Figure 5 Shown, combined Figures 1 to 3 It can be seen that the elevator 3 includes a frame 31 and a conveyor belt 32 circulating on the frame 31. According to different positions, the conveyor belt 32 includes a return section 32a located below the belt filter 1, a reuse section 32c located above the head end of the belt filter 1, and a lifting section 32b connecting the return section 32a and the reuse section 32c; wherein, the running direction of the return section 32a (referring to the side facing the belt filter 1) is consistent with the rotation direction of the filter cloth 11, the lifting section 32b is a vertical lifting section 32b, and the running direction of the reuse section 32c (referring to the side facing the belt filter 1) is consistent with the forward direction of the filter cloth 11.

[0028] Since the lifting section 32b is lifted vertically, the surface of the conveyor belt 32 is provided with a plurality of material blocking members 33 arranged in sequence along the running direction of the conveyor belt 32. Each material blocking member 33 is set at an angle with the conveyor belt 32, and the angle can be selected to be 30-60°. This embodiment has no special requirements for this so that a material accumulation trough is formed between the two, so that the conveyor belt 32 can lift the suspension of powdered adsorbent vertically upward.

[0029] In this embodiment, the running speed of the filter cloth 11 can be set between 0.5-3 m / min, and the running speed of the conveyor belt 32 is greater than 5 m / min; the suitable running speed of the filter cloth 11 is to avoid water leakage between the solid-liquid separation area, the smoking area and the desorption area of ​​each section of the belt filter 1, and the relatively large running speed of the conveyor belt 32 can improve the adsorbent recovery efficiency.

[0030] (3) separating the powdered adsorbent from the elevator 3; In order to prevent the powdered adsorbent suspension on the lifting section 32b from being lost after entering the recycling section 32c, Figure 5 As shown, at the head end of the belt filter 1, a collecting hopper 34 is provided on the frame 31, and the top opening width of the collecting hopper 34 is equivalent to the length of the recycling section 32c, and is used to receive the powdered adsorbent suspension falling from the recycling section 32c.

[0031] Similarly, in order to prevent any powdered adsorbent residue from adhering to the conveyor belt 32, a flushing pipe 35 for flushing the powdered adsorbent from the recycling section 32c is provided on the collecting hopper 34; the present embodiment has no restriction on the number of flushing pipes 35, and the flushing fluid used in the flushing pipes 35 can be a liquid (such as a stock solution) or a gas-water mixed fluid, and the present embodiment has no requirements for this.

[0032] It should be noted that since a material blocking member 33 is provided on the surface of the conveyor belt 32, it is necessary to pay more attention to the flushing angle of the flushing pipe 35 (the flushing directions of different flushing pipes 35 may be the same or different), that is, the flushing direction of at least one flushing pipe 35 must be opposite to the running direction of the conveyor belt 32 to flush the material accumulation trough as much as possible.

[0033] In a more preferred case, Figure 6 As shown, according to statistics, all the flushing holes arranged on each flushing pipe 35 have three flushing directions: opposite to the running direction of the conveyor belt 32, perpendicular to the conveyor belt 32, and the same as the running direction of the conveyor belt 32; in this way, the inside of the material accumulation trough and both sides of the material blocking member 33 can be fully flushed.

[0034] Likewise, the flushing pipe 35 for flushing water toward the inner wall of the collecting hopper 34 may also have a variety of different flushing directions.

[0035] Obviously, the flushing holes with different flushing directions can be simultaneously arranged on one flushing pipe 35 , or can be dispersedly arranged on different flushing pipes 35 . This embodiment has no special requirements for this.

[0036] Table 1 1 According to the data in Table 1, the reasonable matching of gas and liquid flow rates has a significant effect on the adsorbent recovery rate. Examples 1-8 achieved a high adsorbent recovery rate of 95.5%-99.8% by adjusting the gas-liquid flow ratio (0.2-0.5m³ / h gas and 0.8-2m³ / h liquid) and controlling the pressure in the range of 0.404-0.584MPa. In particular, Example 7 achieved a peak recovery rate of 99.8% under the conditions of gas flow rate of 0.5m³ / h, liquid flow rate of 1.2m³ / h, and pressure of 0.584MPa, indicating that appropriately increasing the liquid phase ratio helps to enhance the mass transfer efficiency. Comparative experiments show that the recovery rates in the single-phase system (Comparative Example 1 without gas or Comparative Example 3 without liquid) dropped to 85.5% and 65.7%, respectively, confirming the criticality of gas-liquid synergy. When a single-phase liquid system is used, in order to achieve an adsorbent recovery rate of more than 99.0%, the liquid flow rate needs to reach more than 5.0 m³ / h (see Comparative Example 2), which will cause the water content of the washed adsorbent suspension to be too high.

Claims

1. A non-destructive recovery process for powdered adsorbent based on a belt filter, comprising a first separation step of collecting the powdered adsorbent at the tail end of the belt filter (1), characterized in that: In the first separation step, at least an air-water mixed fluid is used to wash the filter cloth (11) so as to separate the powdery adsorbent from the filter cloth (11).

2. The method for non-destructive recovery of powdered adsorbent according to claim 1, characterized in that: An air-water mixed fluid is dispensed onto the filter cloth (11) by means of an air-water mixed discharger (2). The air-water mixed discharger (2) comprises at least one dispensing pipe (21). The dispensing pipe (21) is arranged on a rotation path of the filter cloth (11) and is located on the inner side of the filter cloth (11). The dispensing pipe (21) is provided with a plurality of dispensing holes for spraying the air-water mixed fluid onto the filter cloth (11).

3. The method for non-destructive recovery of powdered adsorbent according to claim 1, characterized in that: The gas flow rate of the gas-water mixed fluid is 0.2-0.5 m³ / h, and the liquid flow rate is 0.8-2.0 m³ / h.

4. The method for non-destructive recovery of powdered adsorbent according to claim 1, characterized in that: In the gas-water mixed fluid, the gas is compressed air; In the gas-water mixed fluid, the liquid is an original liquid or a desorption liquid.

5. The method for non-destructive recovery of powdered adsorbent according to any one of claims 1 to 4, characterized in that: Also includes: The collected powdered adsorbent is transported to the lifting step at the head end of the same belt filter (1) by using a lifting machine (3).

6. The method for non-destructive recovery of powdered adsorbent according to claim 5, characterized in that: The elevator (3) comprises a frame (31) and a conveyor belt (32) cyclically running on the frame (31); The conveyor belt (32) comprises a return section (32a) located below the belt filter (1), a reuse section (32c) located above the head end of the belt filter (1), and a lifting section (32b) connecting the return section (32a) and the reuse section (32c); The running direction of the return section (32a) is consistent with the rotation direction of the filter cloth (11), and the running direction of the recycling section (32c) is consistent with the forward direction of the filter cloth (11).

7. The method for non-destructive recovery of powdered adsorbent according to claim 6, characterized in that: The surface of the conveyor belt (32) is provided with a plurality of material blocking members (33) arranged in sequence along the running direction of the conveyor belt (32), a material accumulation groove is formed between the material blocking members (33) and the conveyor belt (32), and the angle between the material blocking members (33) and the conveyor belt (32) is 30-60 degrees.

8. The method for non-destructive recovery of powdered adsorbent according to claim 6, characterized in that: The running speed of the filter cloth (11) is 0.5-3 m / min, and the running speed of the conveyor belt (32) is greater than 5 m / min.

9. The method for non-destructive recovery of powdered adsorbent according to claim 6, characterized in that: At the head end of the belt filter (1), the frame (31) is provided with a collecting hopper (34) for receiving the powdered adsorbent dropped from the recycling section (32c); The collecting hopper (34) is provided with a flushing pipe (35) for flushing the powdered adsorbent from the recycling section (32c) and / or the collecting hopper (34).

10. The method for non-destructive recovery of powdered adsorbent according to claim 5, characterized in that: Also included is a second separation step of separating the powdered adsorbent from the elevator (3); In the second separation step, at least a liquid or a gas-water mixed fluid is used to flush the conveyor belt (32) of the elevator (3).

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