Synergistic removal system for insoluble substances and copper ions in 1, 4-butynediol

Abstract

The invention discloses a synergistic removal system for insoluble substances and copper ions in 1, 4-butynediol, and particularly relates to the technical field of chemical separation and purification, the system comprises a reaction unit, a ceramic membrane unit and a filter pressing unit; the reaction unit comprises a reaction kettle and is used for receiving a crude 1, 4-butynediol material and adding alkali liquor for reaction, so that copper ions are converted into copper insoluble substances and are agglomerated to form particulate matters; the ceramic membrane unit comprises a ceramic membrane ultrafiltration device which is used for filtering reaction liquid from the reaction unit. According to the synergistic removal system for the insoluble substances and the copper ions in the 1, 4-butynediol, the copper ions are converted into copper insoluble substances through the reaction unit, the copper insoluble substances are agglomerated to form particulate matters, synergistic filtration of the ceramic membrane unit and the filter pressing unit is combined, the insoluble substances and the copper ions in the crude 1, 4-butynediol can be synchronously removed, the purification effect is improved, and the production cost is reduced. The SS concentration is reduced to 0.01-0.05 mg / L, and the copper ion concentration is reduced to 0.09-0.18 mg / L, so that the stable operation of the subsequent hydrogenation process and the product quality are effectively guaranteed.

Description

Technical Field

[0001] This invention relates to the field of chemical separation and purification technology, and in particular to a synergistic removal system for insoluble substances and copper ions in 1,4-butynediol. Background Technology

[0002] Currently, in some acetylacetonate-aldehyde process for producing 1,4-butanediol (BDO), the product quality and output are affected by insoluble solids (SS) and copper ions carried in the industrial intermediates of 1,4-butynediol (BYD), making it difficult to consistently maintain quality during production. Furthermore, the high-pressure hydrogenation process suffers a significant reduction in operational life due to the introduction of acetylation impurities, severely impacting the economic efficiency of the unit. Therefore, before producing 1,4-butanediol, it is necessary to purify the crude 1,4-butynediol to ensure the smooth operation of subsequent processes. The existing technology has the following problems: Currently, the purification of crude BYD mainly uses aluminum-nickel adsorbents to remove copper ions, but insoluble substances are not removed, affecting product quality. Furthermore, using aluminum-nickel adsorbents requires regeneration, generating a certain amount of hazardous solid waste, causing environmental pollution and increased costs. Summary of the Invention

[0003] The main objective of this invention is to provide a synergistic removal system for insoluble matter and copper ions in 1,4-butynediol. This system can effectively solve the problems of existing technologies that use aluminum-nickel adsorbents to remove copper ions, such as the inability to remove insoluble matter simultaneously, the need to regenerate the adsorbent and generate hazardous solid waste, which leads to unstable product quality, short operating life of subsequent hydrogenation processes, environmental pollution and increased costs.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A synergistic removal system for insoluble matter and copper ions in 1,4-butynediol is disclosed. The system comprises a reaction unit, a ceramic membrane unit, and a pressure filtration unit. The reaction unit includes a reaction vessel for receiving crude 1,4-butynediol material and adding alkaline solution to react, causing copper ions to be converted into copper-insoluble matter and agglomerate into particulate matter. The ceramic membrane unit includes a ceramic membrane ultrafiltration device for filtering the reaction solution from the reaction unit to obtain permeate and concentrate. The pressure filtration unit includes a pressure filtration device for pressing and filtering the concentrate from the ceramic membrane unit to obtain filtrate and filter cake. The filtrate outlet of the pressure filtration device is connected to the material inlet of the ceramic membrane ultrafiltration device via a circulation pipeline, allowing the filtrate to return to the ceramic membrane unit for recycling.

[0005] Preferably, the system further includes: a raw material pump, an alkali tank, a discharge pump, a filter press pump, and a circulation pump; the reactor includes a reactor inlet, a reactor alkali inlet, and a reactor outlet; the raw material pump is connected to the reactor inlet of the reactor for conveying crude 1,4-butynediol material; the alkali tank is connected to an alkali outlet and is connected to the reactor alkali inlet of the reactor via a metering pump for adding alkali solution to the reactor; the discharge pump is connected to a material pipe, which connects the reactor outlet of the reactor to the material inlet of the ceramic membrane ultrafiltration device; the filter press pump is connected between the concentrate outlet of the ceramic membrane ultrafiltration device and the mixed liquid inlet of the filter press device; the circulation pump is connected between the filtrate outlet of the filter press device and the material inlet of the ceramic membrane ultrafiltration device, and the circulation pump includes a circulation pipe connected to the material pipe.

[0006] Preferably, the system further includes: a first buffer tank and a second buffer tank. The first buffer tank includes a first circulating liquid inlet, a first circulating liquid outlet, and a first drain valve. The first circulating liquid inlet is connected to the concentrate outlet of the ceramic membrane ultrafiltration device, and the first circulating liquid outlet is connected to the filter press pump. The second buffer tank includes a second circulating liquid inlet, a second circulating liquid outlet, and a second drain valve. The second circulating liquid inlet is connected to the filtrate outlet of the filter press device, and the second circulating liquid outlet is connected to the circulating pump. Both the first drain valve and the second drain valve are used for draining wastewater.

[0007] Preferably, the reaction vessel is equipped with a stirrer.

[0008] Preferably, the operating conditions of the reaction unit include: reaction temperature ≥90℃, the alkaline solution used is a sodium hydroxide solution with a concentration of 10~30wt%, stirring speed 10-50rpm, pH value of the reaction system 6.6-8.5, and reaction time 10-30min.

[0009] Preferably, the ceramic membrane in the ceramic membrane ultrafiltration device has a pore size of 10-100 nm, and the operating conditions are: membrane surface flow rate of 1-4 m / s and operating pressure of 0.05-1.5 MPa.

[0010] Preferably, the filter cloth material used in the filter press is PPS or PTFE, the filter cloth pore size is 0.05-0.5μm, and the operating pressure is 0.05-1.0MPa.

[0011] Preferably, the permeate outlet of the ceramic membrane ultrafiltration device is connected to a finished product tank, which is provided with a liquid inlet and a discharge outlet for receiving, storing and discharging the purified 1,4-butynediol product.

[0012] Preferably, an insoluble matter recovery box is provided downstream of the filter press device for collecting the filter cake formed after filter pressing.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides a synergistic removal system for insoluble matter and copper ions in 1,4-butynediol. The system converts copper ions into copper-based insoluble matter through a reaction unit, which then agglomerates into particulate matter. Combined with the synergistic filtration of a ceramic membrane unit and a pressure filter unit, it can simultaneously remove insoluble matter and copper ions from crude 1,4-butynediol, improving the purification effect and reducing the SS concentration to 0.01-0.05 mg / L and the copper ion concentration to 0.09-0.18 mg / L. This effectively ensures the stable operation of subsequent hydrogenation processes and product quality.

[0014] 2. This invention provides a synergistic removal system for insoluble matter and copper ions in 1,4-butynediol. Compared with the traditional method using aluminum-nickel adsorbents, this invention eliminates the need for adsorbent regeneration, avoids the generation of hazardous solid waste, and reduces environmental pollution. At the same time, the concentrated liquid is filtered and the filter cake is recovered through a filter press unit, realizing the resource utilization of insoluble matter and reducing the overall treatment cost.

[0015] 3. This invention provides a synergistic removal system for insoluble matter and copper ions in 1,4-butynediol. The filtrate from the pressure filtration unit is returned to the ceramic membrane unit for recycling through a circulation pipeline. This allows any unretained microparticles to collide and agglomerate within the system before being removed again, thus fully recovering the 1,4-butynediol component and reducing raw material loss. At the same time, the first and second buffer tanks in the system effectively buffer flow fluctuations, ensuring continuous and stable operation of the system. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the process flow of the present invention; Figure 2 This is a schematic diagram of device connection according to an embodiment of the present invention.

[0017] In the diagram: 10. Reactor; 101. Reactor inlet; 102. Reactor alkali inlet; 103. Reactor outlet; 11. Stirrer; 12. Raw material pump; 13. Metering pump; 14. Alkali tank; 141. Alkali outlet; 20. Ceramic membrane ultrafiltration unit; 201. Material inlet; 202. Permeate outlet; 203. Concentrate outlet; 21. Discharge pump; 211. Material pipe; 23. First buffer tank; 231. First circulation... 232. Liquid inlet; 233. First circulating liquid outlet; 234. First drain valve; 26. Circulation pump; 261. Circulation pipe; 30. Filter press; 301. Mixed liquid inlet; 302. Filtrate outlet; 31. Second buffer tank; 311. Second circulating liquid inlet; 312. Second circulating liquid outlet; 313. Second drain valve; 32. Filter press pump; 40. Finished product tank; 401. Liquid inlet; 402. Discharge port; 50. Insoluble matter recovery box. Detailed Implementation

[0018] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0019] Example 1 like Figure 1 , Figure 2 As shown, a synergistic removal system for insoluble matter and copper ions in 1,4-butynediol includes a reaction vessel 10, a ceramic membrane ultrafiltration device 20, and a filter press 30. A stirrer 11 is installed inside the reaction vessel. A raw material pump 12 is connected to the reaction vessel inlet 101 of the reaction vessel 10. The alkali outlet 141 of the alkali tank 14 is connected to the reaction vessel inlet 102 of the reaction vessel 10 via a metering pump 13. The alkali tank is used to hold a sodium hydroxide solution with a concentration of 10-30 wt%. The metering pump 13 can meter the sodium hydroxide solution in the alkali tank and input it into the reaction vessel. The reaction vessel outlet 103 at the bottom of the reaction vessel 10 is connected to the inlet of the discharge pump 21. The outlet of the discharge pump 21 is connected to the material inlet 201 of the ceramic membrane ultrafiltration device 20 via a material pipe 211.

[0020] The permeate outlet 202 of the ceramic membrane ultrafiltration device 20 is connected to the liquid inlet 401 of the finished product tank 40, and a discharge port 402 is provided at the bottom of the finished product tank 40. In this embodiment, the pore size of the ceramic membrane in the ceramic membrane ultrafiltration device is 10-100 nm, and the ceramic membrane ultrafiltration device can perform filtration at a membrane surface flow rate of 1-4 m / s and an operating pressure of 0.05-1.5 MPa.

[0021] The concentrate outlet 203 of the ceramic membrane ultrafiltration device 20 is connected to the first circulating liquid inlet 231 at the upper end of the first buffer tank 23, and the first circulating liquid outlet 232 at the lower end of the first buffer tank 23 is connected to the mixed liquid inlet 301 of the filter press device via the filter press pump 32. The filter press pump 32 is used to pump the concentrate in the first buffer tank 23 into the filter press device for filtration.

[0022] The filtrate outlet 302 of the filter press 30 is connected to the second circulating liquid inlet 311 at the upper end of the second buffer tank 31, and the second circulating liquid outlet 312 at the lower end of the second buffer tank 31 is connected to the inlet of the circulating pump 26. The outlet of the circulating pump 26 is connected to the material pipe via the circulating pipe 261, so that the second circulating liquid outlet 312 is connected to the material inlet 201 of the ceramic membrane ultrafiltration device via the circulating pump 26. The circulating pump 26 is used to pump the filtrate in the second buffer tank 31 into the ceramic membrane ultrafiltration device for further concentration.

[0023] A first drain valve 233 and a second drain valve 313 are respectively installed at the bottom of the first buffer tank 23 and the second buffer tank 31.

[0024] When this embodiment is run, the following steps are performed: Crude BYD material is pumped into reactor 10 by a raw material pump. Sodium hydroxide solution is metered by metering pump 13 and then pumped into reactor 10 to adjust the pH value of the crude BYD material and initiate the reaction, forming a reaction solution. Copper ions in the crude BYD material precipitate as copper precipitates. The reaction solution is then concentrated in ceramic membrane ultrafiltration device 20 by discharge pump 21 to separate SS and copper precipitates and other impurities. The permeate produced by the ceramic membrane ultrafiltration device is stored in finished product tank 40 as the BYD component for later use.

[0025] The concentrate produced by the ceramic membrane ultrafiltration device first enters the first buffer tank for temporary storage. The concentrate in the first buffer tank is then pumped into the filter press device 30 by the filter press pump 32 for filtration. The filtrate produced by the filter press device first enters the second buffer tank for temporary storage. The filtrate in the second buffer tank is then pumped into the ceramic membrane ultrafiltration device by the circulation pump for circulation filtration to recover the BYD component.

[0026] The filter cake produced by the filter press enters the insoluble matter recovery box 50 for partial recycling.

[0027] Operating conditions and parameters Reaction unit operating conditions: reaction temperature ≥90℃, sodium hydroxide solution concentration 10~30 wt%, stirring speed 10~50 rpm, pH value of the reaction system 6.6~8.5, reaction time 10~30 min. During the reaction, copper ions react with sodium hydroxide and excess formaldehyde to generate copper-insoluble substances, which then agglomerate to form particulate matter. The reaction equation is as follows: Cu 2+ + 2OH - → Cu(OH)2 (1) 2Cu(OH)2 + OH - + HCHO → Cu2O↓ +HCOO - + 3H2O (2) Cu2O + OH - + HCHO → 2Cu↓ + HCOO - + H2O (3) Operating conditions for the ceramic membrane unit: The ceramic membrane ultrafiltration unit 20 uses ceramic membranes with a pore size of 10~100 nm, a membrane surface flow rate of 1~4 m / s, and an operating pressure of 0.05~1.5 MPa. The ceramic membrane unit is used to filter the reaction solution, removing insoluble matter and copper particles. The permeate, as the purified product, enters the finished product tank 40, and the concentrate enters the pressure filter unit. Operating conditions of the filter press unit: The filter press unit 30 uses PPS or PTFE filter cloth with a pore size of 0.05~0.5 μm and an operating pressure of 0.05~1.0 MPa. The filter press unit filters the concentrate, and the filtrate is returned to the ceramic membrane unit for recycling. The filter cake is recovered and reused.

[0028] The following uses crude BYD material from a domestic manufacturer as an example to further illustrate the effect of adopting this application. The relevant parameters of the crude BYD material sample are shown in Table 1.

[0029] Table 1 Parameters of crude BYD material samples Example 2 Crude BYD material enters the reactor, and sodium hydroxide solution (10wt%) is added to adjust the pH to 6.6. The reaction time is 10 minutes, and the stirrer speed is 10 rpm, causing copper ions to precipitate as copper precipitates. The particle size of the insoluble components is 4.89 μm. The reaction solution is then pumped into a ceramic membrane ultrafiltration unit. The ceramic membrane in the ultrafiltration unit has a pore size of 10 nm, a surface flow rate of 1 m / s, and an operating pressure of 0.05 MPa to filter out SS and copper precipitates and other impurities. The concentrated solution produced by the ceramic membrane ultrafiltration unit enters a filter press unit. The filter press unit uses PPS filter cloth with a pore size of 0.5 μm and a filtration pressure of 0.05 MPa to press the insoluble components into a cake. The filtrate is returned to the ceramic membrane ultrafiltration unit, effectively recovering the BYD component. The permeate from the ceramic membrane ultrafiltration unit enters the finished product tank.

[0030] Example 3 Crude BYD material enters the reactor, and sodium hydroxide solution (20wt%) is added to adjust the pH to 7.0. The reaction time is 20 minutes, and the stirrer speed is 25 rpm, causing copper ions to precipitate as copper precipitates. The particle size of the insoluble components is 5.01 μm. The reaction solution is then pumped into a ceramic membrane ultrafiltration unit. The ceramic membrane in the ultrafiltration unit has a pore size of 50 nm, a surface flow rate of 2 m / s, and an operating pressure of 0.50 MPa, filtering out SS and copper precipitates and other impurities. The concentrated solution produced by the ceramic membrane ultrafiltration unit enters a filter press unit. The filter press unit uses PPS filter cloth with a pore size of 0.1 μm and a filtration pressure of 0.5 MPa, pressing the insoluble components into a cake. The filtrate is returned to the ceramic membrane ultrafiltration unit, effectively recovering the BYD component. The permeate from the ceramic membrane ultrafiltration unit enters the finished product tank.

[0031] Example 4 Crude BYD material enters the reactor, and sodium hydroxide solution (30wt%) is added to adjust the pH to 8.5. The reaction time is 30 minutes, and the stirrer speed is 50 rpm, causing copper ions to precipitate as copper precipitates. The particle size of the insoluble components is 5.81 μm. The reaction solution is then pumped into a ceramic membrane ultrafiltration unit. The ceramic membrane in the ultrafiltration unit has a pore size of 100 nm, a surface flow rate of 4 m / s, and an operating pressure of 1.50 MPa to filter out SS and copper precipitates and other impurities. The concentrated solution produced by the ceramic membrane ultrafiltration unit enters a filter press unit. The filter press unit uses PTFE filter cloth with a pore size of 0.05 μm and a filtration pressure of 1.5 MPa to press the insoluble components into a cake. The filtrate is returned to the ceramic membrane ultrafiltration unit, effectively recovering the BYD component. The permeate from the ceramic membrane ultrafiltration unit enters the finished product tank.

[0032] The particle size analysis of the insoluble matter in the reaction solution of each embodiment is shown in Table 2.

[0033] Table 2. Particle size of insoluble matter in the reaction solution of each embodiment The processing effects of each embodiment are shown in Table 3.

[0034] Table 3 Processing effects of each embodiment The data in Table 3 show that by using this application, insoluble matter and copper ions in crude BYD can be removed simultaneously, thus improving the removal effect.

[0035] The working principle of the synergistic removal system for insoluble substances and copper ions in 1,4-butynediol will be explained in detail below.

[0036] like Figure 1 , Figure 2As shown, during system operation, crude BYD material is pumped to reactor 10 via raw material pump 12. Simultaneously, sodium hydroxide solution from alkali tank 14 is quantitatively added to reactor 10 via metering pump 13 to adjust the pH of the material to 6.6-8.5. Under the action of stirrer 11, a chemical reaction occurs in reactor 10, where copper ions are converted into copper-insoluble substances such as Cu(OH)2, Cu2O, and Cu, and agglomerate to form particulate matter. The reaction time is 10-30 min. The reaction solution is pumped to ceramic membrane ultrafiltration unit 20 via discharge pump 21, where ultrafiltration is performed under conditions of membrane surface flow rate of 1-4 m / s and operating pressure of 0.05-1.5 MPa. The ceramic membrane unit separates the reaction solution into permeate and concentrate: the permeate is the purified BYD product, which is stored in finished product tank 40 for subsequent hydrogenation processes; the concentrate contains insoluble matter and copper-like particles and is temporarily stored in first buffer tank 23. The concentrate in the first buffer tank 23 is pumped to the filter press 30 via the filter press pump 32, where it is filtered at an operating pressure of 0.05~1.0 MPa. The filter press 30 separates the concentrate into filtrate and filter cake: the filter cake, a solid mixture of insoluble matter and copper particles, is discharged to the insoluble matter recovery tank 50 for recovery or harmless treatment; the filtrate enters the second buffer tank 31 for temporary storage. The filtrate in the second buffer tank 31 is returned to the material inlet 201 of the ceramic membrane ultrafiltration device 20 via the circulation pump 26, where it is mixed with fresh reaction liquid and ultrafiltration is performed again. This circulation process causes the tiny particles that pass through the filter press to collide and agglomerate within the ceramic membrane system, forming large insoluble particles, which are ultimately retained in the filter press 30, achieving full recovery of BYD components and thorough removal of impurities. The first buffer tank 23 and the second buffer tank 31 are used to buffer flow fluctuations and improve the stability of continuous system operation. The first drain valve 233 and the second drain valve 313 are used to periodically remove sediment from the tanks.

[0037] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A synergistic removal system for insoluble substances and copper ions in 1,4-butynediol, characterized in that: The system includes a reaction unit, a ceramic membrane unit, and a pressure filtration unit. The reaction unit includes a reaction vessel (10) for receiving crude 1,4-butynediol material and adding alkaline solution to react, so that copper ions are converted into copper-insoluble substances and agglomerate to form particulate matter. The ceramic membrane unit includes a ceramic membrane ultrafiltration device (20) for filtering the reaction liquid from the reaction unit to obtain permeate and concentrate. The pressure filtration unit includes a pressure filtration device (30) for pressing and filtering the concentrate from the ceramic membrane unit to obtain filtrate and filter cake. The filtrate outlet (302) of the pressure filtration device (30) is connected to the material inlet (201) of the ceramic membrane ultrafiltration device (20) through a circulation pipeline, so that the filtrate is returned to the ceramic membrane unit for recycling.

2. The synergistic removal system for insoluble matter and copper ions in 1,4-butynediol according to claim 1, characterized in that: The system also includes: a raw material pump (12), an alkali tank (14), a discharge pump (21), a filter press pump (32), and a circulation pump (26); the reactor (10) includes a reactor inlet (101), a reactor alkali inlet (102), and a reactor outlet (103); the raw material pump (12) is connected to the reactor inlet (101) of the reactor (10) for conveying crude 1,4-butynediol material; the alkali tank (14) is connected to an alkali outlet (141) and is connected to the reactor alkali inlet (102) of the reactor (10) via a metering pump (13) for adding alkali solution into the reactor; the discharge pump (21) is connected to a material pipe ( 211), the material pipe (211) is connected between the reactor outlet (103) of the reactor (10) and the material inlet (201) of the ceramic membrane ultrafiltration device (20); the filter press pump (32) is connected between the concentrate outlet (203) of the ceramic membrane ultrafiltration device (20) and the mixed liquid inlet (301) of the filter press device (30); the circulation pump (26) is connected between the filtrate outlet (302) of the filter press device (30) and the material inlet (201) of the ceramic membrane ultrafiltration device (20), and the circulation pump (26) includes a circulation pipe (261), which is connected to the material pipe (211).

3. The synergistic removal system for insoluble matter and copper ions in 1,4-butynediol according to claim 2, characterized in that: The system further includes: a first buffer tank (23) and a second buffer tank (31). The first buffer tank (23) includes a first circulating liquid inlet (231), a first circulating liquid outlet (232), and a first drain valve (233). The first circulating liquid inlet (231) is connected to the concentrate outlet (203) of the ceramic membrane ultrafiltration device (20), and the first circulating liquid outlet (232) is connected to the filter press pump (32). The second buffer tank (31) includes a second circulating liquid inlet (311), a second circulating liquid outlet (312), and a second drain valve (313). The second circulating liquid inlet (311) is connected to the filtrate outlet (302) of the filter press device (30), and the second circulating liquid outlet (312) is connected to the circulating pump (26). Both the first drain valve (233) and the second drain valve (313) are used for draining.

4. The synergistic removal system for insoluble matter and copper ions in 1,4-butynediol according to claim 1, characterized in that: A stirrer (11) is installed inside the reactor (10).

5. The synergistic removal system for insoluble matter and copper ions in 1,4-butynediol according to claim 1, characterized in that: The operating conditions of the reaction unit include: reaction temperature ≥90℃, the alkaline solution used is a sodium hydroxide solution with a concentration of 10~30wt%, stirring speed 10-50rpm, pH value of the reaction system 6.6-8.5, and reaction time 10~30min.

6. The synergistic removal system for insoluble matter and copper ions in 1,4-butynediol according to claim 1, characterized in that: The ceramic membrane in the ceramic membrane ultrafiltration device (20) has a pore size of 10-100nm and operating conditions of 1-4m / s at the membrane surface and 0.05-1.5MPa at the operating pressure.

7. The synergistic removal system for insoluble substances and copper ions in 1,4-butynediol according to claim 1, characterized in that: The filter cloth material used in the filter press device (30) is PPS or PTFE, the filter cloth pore size is 0.05-0.5μm, and the operating pressure is 0.05-1.0MPa.

8. The synergistic removal system for insoluble matter and copper ions in 1,4-butynediol according to claim 1, characterized in that: The permeate outlet (202) of the ceramic membrane ultrafiltration device (20) is connected to a finished product tank (40), which is provided with a liquid inlet (401) and a discharge port (402) for receiving, storing and discharging the purified 1,4-butynediol product.

9. The synergistic removal system for insoluble matter and copper ions in 1,4-butynediol according to claim 1, characterized in that: Downstream of the filter press (30) is an insoluble matter recovery box (50) for collecting the filter cake formed after filter pressing.

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