A recovery system and recovery method of a chromium-free passivation liquid for aerosol spraying

Abstract

The present application relates to a kind of gas mist spray chrome-free passivation liquid recovery system, the recovery system includes passivation liquid preparation tank, passivation liquid collection tank, passivation liquid separation tank, passivation liquid aerosol nozzle, passivation liquid interception mechanism, redundant passivation liquid collection mechanism, passivation liquid collection box, spray pressurizing pump and filter, the passivation liquid preparation tank is connected with passivation liquid aerosol nozzle by filter, spray pressurizing pump, passivation liquid aerosol nozzle is equipped with passivation liquid interception mechanism in tinplate, passivation liquid interception mechanism and tinplate opposite redundant passivation liquid collection mechanism are equipped with, redundant passivation liquid collection mechanism is connected with passivation liquid collection box, passivation liquid collection box is connected with passivation liquid collection tank, the scheme improves working environment, realizes the stable recycling of chrome-free passivation liquid, realizes the efficient, low cost, stable production of chrome-free passivation tinplate.

Description

TECHNICAL FIELD

[0001] The application relates to a chromium-free passivation liquid recovery system, in particular to an air-spray chromium-free passivation liquid recovery system, and belongs to the technical field of tinplate production in the metallurgical industry. BACKGROUND

[0002] At present, the production of tinplate at home and abroad all adopts the process of chromium passivation, and the passivation process adopts sodium dichromate solution to electrolytically passivate the tin layer on the surface of tinplate. Since sodium dichromate is a highly toxic medium, in order to ensure safe production and avoid a large amount of investment in waste liquid treatment, and at the same time, the use range of chromium passivation products for food safety will become narrower and narrower, such as the EU RoHS regulation, although the directive is currently suspended, but it cannot change the general direction of chromium-free passivation of tinplate.

[0003] The mainstream technology for chromium-free passivation of tinplate is a spraying type chromium-free passivation system, which uniformly sprays chromium-free passivation liquid onto the surface of tinplate, and forms a chromium-free passivation film after drying. According to the passivation mechanism, the chromium-free passivation liquid can be divided into organic and inorganic two kinds, but no matter which kind of chromium-free passivation liquid is required to be uniformly covered on the surface of tinplate. In order to ensure that the chromium-free passivation liquid is uniformly sprayed on the surface of tinplate, it is an important prerequisite that the droplet diameter of the chromium-free passivation liquid sprayed on the surface of the steel plate is small. In order to obtain small droplets of chromium-free passivation liquid, the air-spray method is a practical method. The air-spray method is to atomize the chromium-free passivation liquid in the gasification chamber, and under the action of high-pressure gas, the small droplets after atomization are sprayed onto the surface of the tinplate. Since the droplet particles after atomization are small, they are easy to flow with the gasification gas. If these chromium-free passivation liquids floating in the gasification gas are not recovered, it will pollute the environment, and also cause waste of chromium-free passivation liquid.

[0004] The core technology of the spraying chromium-free passivation method is to uniformly spray the passivation liquid onto the surface of the plate according to the requirements of different tinplate, and at the same time, the chromium-free passivation liquid is expensive, and needs to be recycled. CN211057225U discloses a chromium-free passivation equipment, which sprays the diluted chromium-free passivation liquid onto the surface of the plate by using a rotary spraying technology, which is the mainstream equipment for chromium-free passivation at present. The main problem of spraying chromium-free passivation liquid by using the rotary spraying method is that it is difficult to ensure the uniform distribution of chromium-free passivation liquid on the surface of the plate, which increases the consumption of chromium-free passivation liquid. In order to improve the recovery efficiency of the spraying type chromium-free passivation liquid and improve the environment of the spraying area, it is urgent to invent an air-spray chromium-free passivation liquid recovery system, which is of great significance to improve the green manufacturing technology and product quality of tinplate. SUMMARY

[0005] The present application is just for the technical problems existing in the prior art, providing a kind of gas mist spray chrome-free passivation liquid recovery system and method, improve working environment, realize the stable recycling of chrome-free passivation liquid, realize the efficient, low cost, stable production of chrome-free passivated tin plate.The whole scheme design is ingenious, compact structure, easy to use, safe, can realize the production of various specifications of tin plate, ensure that the chrome-free passivation liquid is coated uniformly on the surface of tin plate, and the recovery rate of chrome-free passivation liquid reaches more than 95%.

[0006] In order to achieve the above purpose, the technical scheme of the present application is as follows: a gas mist spray chrome-free passivation liquid recovery system, the recovery system includes passivation liquid preparation tank, passivation liquid collection tank, passivation liquid separation tank, passivation liquid aerosol nozzle, passivation liquid interception mechanism, redundant passivation liquid collection mechanism, passivation liquid collection box, jet pressurizing pump, filter.The passivation liquid preparation tank is connected with the passivation liquid aerosol nozzle through the filter and the jet pressurizing pump, the passivation liquid aerosol nozzle is provided with the passivation liquid interception mechanism between the tin plate, the passivation liquid interception mechanism and the tin plate are provided with the redundant passivation liquid collection mechanism, the redundant passivation liquid collection mechanism is connected with the passivation liquid collection box, the passivation liquid collection box is connected with the passivation liquid collection tank, the passivation liquid separation tank is connected with the passivation liquid collection box, the passivation liquid separation tank is connected with the passivation liquid collection tank, the passivation liquid collection tank is connected with the passivation liquid preparation tank.The passivation liquid preparation tank is used to prepare chrome-free passivation liquid with different concentrations;The jet pressurizing pump is used to atomize the passivation liquid into fine liquid particles, which are sprayed onto the surface of the tin plate through the passivation liquid aerosol nozzle;The passivation liquid interception mechanism is used to intercept the passivation liquid in the edge atomization area of the fluid sprayed by the nozzle;The redundant passivation liquid collection mechanism is used to collect the redundant passivation liquid sprayed on the opposite side of the tin plate;The passivation liquid collection box is used to collect the passivation liquid of the passivation liquid interception mechanism and the redundant passivation liquid collection mechanism;The passivation liquid separation tank is used to separate the excess gas mist liquid particles in the passivation liquid collection box, and the tail gas is discharged through the exhaust system;The passivation liquid collection tank is used to collect the passivation liquid obtained from the passivation liquid separation tank and the passivation liquid collection box, and then return to the passivation liquid preparation tank.

[0007] As an improvement of the present invention, the passivation liquid in the passivation liquid preparation tank is sent to the passivation liquid aerosol nozzle by the injection pressure pump through the filter, the passivation liquid sprayed from the passivation liquid aerosol nozzle is sprayed onto the surface of the tinplate after passing through the passivation liquid retention mechanism, the redundant passivation liquid collecting mechanism collects the redundant passivation liquid sprayed onto the opposite side of the tinplate, the passivation liquid collected by the passivation liquid retention mechanism and the redundant passivation liquid collecting mechanism flows back to the passivation liquid collection box, the excess aerosol liquid particles in the passivation liquid collection box are separated into gas and liquid by the passivation liquid separation tank, the tail gas is discharged through the exhaust system, and the obtained liquid flows back to the passivation liquid collection tank. As an improvement of the present invention, the passivation liquid retention mechanism is used to intercept the passivation liquid in the edge atomization zone of the fluid ejected from the aerosol nozzle. The passivation liquid retention mechanism is composed of a baffle, a liquid receiving trough, and a liquid receiving reflux trough. The width of the flow area on the baffle is W and the height is H; the distance L1 between the aerosol nozzle and the tinplate is determined by the nozzle characteristics, usually 250 mm; the distance L2 between the passivation liquid retention mechanism and the nozzle is (1 / 2 to 3 / 4) L1, the width W of the flow area is 1.1 to 1.2 times the width of the tinplate, the width W1 of the baffle is (1.05 to 1.2) W, the height H of the flow area is related to L1, H is (1 / 3 to 1 / 2) L1, and a liquid receiving trough is provided on the upper edge of the baffle. The passivation liquid collected in the liquid receiving trough flows into the passivation liquid retention mechanism through the reflux trough, so that the passivation liquid can be recycled to the maximum extent.

[0008] As an improvement of the present invention, in order to make the passivation liquid sprayed onto the tinplate surface more uniform, the width of the passivation liquid spraying needs to be greater than the width of the tinplate. This part of the passivation liquid belongs to redundant passivation liquid and needs to be recycled; the redundant passivation liquid collecting mechanism is arranged on the back of the tinplate spraying surface, the width W1 of the redundant passivation liquid collecting mechanism is comparable to the width of the passivation liquid intercepting mechanism, the window width W of the redundant passivation liquid collecting mechanism is comparable to the width of the intercepting mechanism, and the intercepting mechanism height H1 is (1.1 to 1.3) times of H in the intercepting mechanism; a stainless steel wire mesh placed at 45° is provided inside the intercepting mechanism, and the stainless steel wire mesh can realize gas-liquid separation by the aerosol liquid particles sprayed onto the net, and the passivation liquid can be recycled to the greatest extent. At the same time, it can also prevent the passivation liquid from leaking into the air and causing environmental pollution.

[0009] As an improvement of the present invention, in order to prevent the leakage of the passivation liquid, the passivation liquid aerosol nozzle, the passivation liquid interception mechanism and the redundant passivation liquid collection mechanism are placed in the passivation liquid collection box. The passivation liquid collection box is a square structure, and its size is determined with reference to the actual size of the injection system and the unit. Two narrow slits are respectively provided at the corresponding positions in the middle of the upper and lower parts of the passivation liquid collection box. The width of the narrow slit T = 60 ~ 120mm, and the length of the narrow slit is equivalent to the width W of the passivation liquid interception mechanism; an exhaust port is provided at the upper position of the passivation liquid collection box. The exhaust port is circular, and its diameter D is related to the width and length of the narrow slit. The diameter A drain port is provided at the bottom of the passivation liquid collection box, and the diameter of the drain port is DN = 20 ~ 50 mm; the bottom of the passivation liquid collection box is provided with a certain slope A, A = 1 ~ 3 °, which is conducive to the natural return of the passivation liquid at the bottom of the passivation liquid collection box to the passivation liquid collection tank.

[0010] As an improvement of the present invention, an exhaust system is provided inside the passivation liquid collection box. The exhaust system ensures that a certain negative pressure is formed inside the passivation liquid collection box to prevent the leakage of fine particles of the aerosol passivation liquid. The air volume Q of the exhaust system is determined by the length and width of the narrow slit on the box body.

[0011] As an improvement of the present invention, the air extracted from the box is separated by a coalescing gas-liquid separator. The air volume processed by the separator is consistent with the air volume Q of the exhaust system. The separated liquid flows back to the passivation liquid collection box, and the separated tail gas enters the exhaust system.

[0012] A method for recovering chromium-free passivation liquid by mist spraying, wherein the recovery system comprises the steps of aerosol interception of passivation liquid, recovery of redundant passivation liquid, and recovery of passivation liquid in gas, as follows:

[0013] 1) The passivation liquid in the passivation liquid dispensing tank is sent to the passivation liquid aerosol nozzle by the spray pressure pump through the filter, the passivation liquid sprayed from the passivation liquid aerosol nozzle is sprayed onto the surface of the tinplate after passing through the passivation liquid intercepting mechanism, the redundant passivation liquid collecting mechanism collects the redundant passivation liquid sprayed onto the opposite side of the tinplate, the passivation liquid collected by the passivation liquid intercepting mechanism and the redundant passivation liquid collecting mechanism flows back to the passivation liquid collecting tank, the excess aerosol liquid particles in the passivation liquid collecting tank are separated into gas and liquid by the passivation liquid separation tank, the tail gas is discharged through the exhaust system, and the obtained liquid flows back to the passivation liquid collecting tank;

[0014] 2) The passivation liquid retention mechanism is used to retain the passivation liquid in the edge atomization zone of the fluid ejected from the aerosol nozzle. The passivation liquid retention mechanism consists of a baffle, a liquid receiving trough, and a liquid receiving reflux trough. The width of the flow area on the baffle is W and the height is H. The distance between the aerosol nozzle and the tinplate is L1 (determined by the nozzle characteristics, usually 250mm). The distance between the passivation liquid retention mechanism and the nozzle is L2 = (1 / 2 to 3 / 4) L1. The width W of the flow area is 1.1 to 1.2 times the width of the tinplate. The width W1 of the baffle is W1 = (1.05 to 1.2) W. The height H of the flow area is related to L1, H = (1 / 3 to 1 / 2) L1. A liquid receiving trough is provided on the upper edge of the baffle. The passivation liquid collected in the liquid receiving trough flows into the passivation liquid retention mechanism through the reflux trough.

[0015] 3) A redundant passivation liquid collection mechanism is provided on the back of the spraying surface of the tinplate. The width W1 of the redundant passivation liquid collection mechanism is equivalent to the width of the passivation liquid interception mechanism. The window width W of the redundant passivation liquid collection mechanism is equivalent to the width of the interception mechanism. The height H1 of the interception mechanism is (1.1 to 1.3) times the height H of the interception mechanism. A stainless steel wire mesh placed at a 45° angle is provided inside the interception mechanism. The stainless steel wire mesh can separate the aerosol liquid particles sprayed onto the mesh into gas and liquid.

[0016] 4) The passivation liquid aerosol nozzle, the passivation liquid interception mechanism and the redundant passivation liquid collection mechanism are placed in the passivation liquid collection box. The passivation liquid collection box is a square structure. Two narrow slits are respectively provided at the corresponding positions in the middle of the upper and lower parts of the passivation liquid collection box. The width of the narrow slit T is 60 to 120 mm, and the length of the narrow slit is equivalent to the width W of the passivation liquid interception mechanism. An exhaust port is provided above the passivation liquid collection box. The exhaust port is circular. Its diameter D is related to the width and length of the narrow slit. The diameter A drain port is provided at the bottom of the passivation liquid collection box, and the diameter of the drain port is DN = 20 ~ 50 mm; the bottom of the passivation liquid collection box is provided with a certain slope A, A = 1 ~ 3 degrees;

[0017] 5) Use the exhaust system to achieve a certain negative pressure inside the passivation liquid collection box to prevent the leakage of fine particles of the aerosol passivation liquid. The air volume of the exhaust system

[0018] 6) The air extracted from the exhaust system is separated in the passivation liquid separation tank. The separation method is a coalescing gas-liquid separator. The air volume processed by the separator is consistent with the air volume Q of the exhaust system. The separated liquid flows back to the passivation liquid collection box, and the separated tail gas enters the exhaust system.

[0019] Compared with the existing technology, the present invention has the following advantages: 1) The technical solution is cleverly designed, compact in structure, easy to use and safe, and meets the requirements of efficient and low-cost production of green tinplate; 2) The technical solution can ensure the uniformity of coating of chromium-free passivation liquid on the surface of tinplate, effectively avoid leakage of passivation liquid, greatly improve the working environment, and the recovery rate of chromium-free passivation liquid reaches more than 95%; 3) Through the effective combination of various components of the recovery system, while improving the recovery efficiency of chromium-free passivation liquid, it can also ensure the uniform film formation of chromium-free passivation liquid, achieving the advantages of both quality and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0021] Figure 2 Schematic diagram of the passivation liquid retention mechanism;

[0022] Figure 3 Schematic diagram of the redundant passivation liquid collection mechanism;

[0023] Figure 4 Schematic diagram of passivation solution collection tank.

[0024] In the figure: 1, passivation solution preparation tank, 2, passivation solution collection tank, 3, passivation solution separation tank, 4, passivation solution aerosol nozzle, 5, passivation solution interception mechanism, 6, redundant passivation solution collection mechanism, 7, passivation solution collection tank, 8, jet pressurizing pump, 9, filter, 51, baffle, 52, liquid receiving groove, 53, liquid receiving backflow groove. DETAILED DESCRIPTION

[0025] In order to deepen the understanding of the present application, the following detailed description of the embodiments is combined with the drawings.

[0026] Example 1: see Figures 1-4 A recovery system for aerosol spraying chromium-free passivation solution, the recovery system includes three steps of passivation solution aerosol interception, redundant passivation solution recovery, and recovery of passivation solution in gas, and the recovery system comprises a passivation solution preparation tank 1, a passivation solution collection tank 2, a passivation solution separation tank 3, a passivation solution aerosol nozzle 4, a passivation solution interception mechanism 5, a redundant passivation solution collection mechanism 6, a passivation solution collection tank 7, a jet pressurizing pump 8, and a filter 9. The passivation solution preparation tank 1 is connected with the passivation solution aerosol nozzle 4 through the filter 9 and the jet pressurizing pump 8, the passivation solution aerosol nozzle 4 is provided with the passivation solution interception mechanism 5 between the passivation solution aerosol nozzle 4 and the tinplate, the passivation solution interception mechanism 5 and the tinplate are provided with the redundant passivation solution collection mechanism 6 on the opposite side, the redundant passivation solution collection mechanism 6 is connected with the passivation solution collection tank 7, the passivation solution collection tank 7 is connected with the passivation solution collection tank 2, the passivation solution separation tank 3 is connected with the passivation solution collection tank 7, the passivation solution separation tank 3 is connected with the passivation solution collection tank 2, and the passivation solution collection tank 2 is connected with the passivation solution preparation tank 1. The passivation solution preparation tank 1 is used for preparing chromium-free passivation solution with different concentrations; the jet pressurizing pump 8 is used for atomizing the passivation solution into small liquid particles, which are sprayed to the surface of the tinplate through the passivation solution aerosol nozzle 4; the passivation solution interception mechanism 5 is used for intercepting the passivation solution in the edge atomization area of the fluid sprayed by the nozzle; the redundant passivation solution collection mechanism 6 is used for collecting the redundant passivation solution sprayed to the opposite side of the tinplate; the passivation solution collection tank 7 is used for collecting the passivation solution of the passivation solution interception mechanism 5 and the redundant passivation solution collection mechanism 6; the passivation solution separation tank 3 is used for separating the excess aerosol liquid particles in the passivation solution collection tank 7, and the tail gas is discharged through the air exhaust system; the passivation solution collection tank 2 is used for collecting the passivation solution obtained by the passivation solution separation tank 3 and the passivation solution collection tank 7, and then the passivation solution is backflowed to the passivation solution preparation tank;

[0027] Example 2: see Figures 1-4 A recovery system for aerosol spraying chromium-free passivation solution, the method is as follows:

[0028] 1) The passivation liquid in the passivation liquid dispensing tank is sent to the passivation liquid aerosol nozzle by the spray pressure pump through the filter, the passivation liquid sprayed from the passivation liquid aerosol nozzle is sprayed onto the surface of the tinplate after passing through the passivation liquid intercepting mechanism, the redundant passivation liquid collecting mechanism collects the redundant passivation liquid sprayed onto the opposite side of the tinplate, the passivation liquid collected by the passivation liquid intercepting mechanism and the redundant passivation liquid collecting mechanism flows back to the passivation liquid collecting box, the excess aerosol liquid particles in the passivation liquid collecting box are separated into gas and liquid by the passivation liquid separation tank, the tail gas is discharged through the exhaust system, and the obtained liquid flows back to the passivation liquid collection tank;

[0029] 2) The passivation liquid retention mechanism is used to retain the passivation liquid in the edge atomization zone of the fluid ejected from the aerosol nozzle. The passivation liquid retention mechanism consists of a baffle, a liquid receiving trough, and a liquid receiving reflux trough. The width of the flow area on the baffle is W and the height is H. The distance between the aerosol nozzle and the tinplate is L1 (determined by the nozzle characteristics, usually 250mm). The distance between the passivation liquid retention mechanism and the nozzle is L2 = (1 / 2 to 3 / 4) L1. The width W of the flow area is 1.1 to 1.2 times the width of the tinplate. The width W1 of the baffle is W1 = (1.05 to 1.2) W. The height H of the flow area is related to L1, H = (1 / 3 to 1 / 2) L1. A liquid receiving trough is provided on the upper edge of the baffle. The passivation liquid collected in the liquid receiving trough flows into the passivation liquid retention mechanism through the reflux trough.

[0030] 3) A redundant passivation liquid collection mechanism is provided on the back of the spraying surface of the tinplate. The width W1 of the redundant passivation liquid collection mechanism is equivalent to the width of the passivation liquid interception mechanism. The window width W of the redundant passivation liquid collection mechanism is equivalent to the width of the interception mechanism. The height H1 of the interception mechanism is (1.1 to 1.3) times the height H of the interception mechanism. A stainless steel wire mesh placed at a 45° angle is provided inside the interception mechanism. The stainless steel wire mesh can separate the aerosol liquid particles sprayed onto the mesh into gas and liquid.

[0031] 4) The passivation liquid aerosol nozzle, the passivation liquid interception mechanism and the redundant passivation liquid collection mechanism are placed in the passivation liquid collection box. The passivation liquid collection box is a square structure. Two narrow slits are respectively provided at the corresponding positions in the middle of the upper and lower parts of the passivation liquid collection box. The width of the narrow slit T is 60 to 120 mm, and the length of the narrow slit is equivalent to the width W of the passivation liquid interception mechanism. An exhaust port is provided above the passivation liquid collection box. The exhaust port is circular. Its diameter D is related to the width and length of the narrow slit. The diameter A drain port is provided at the bottom of the passivation liquid collection box, and the diameter of the drain port is DN = 20 ~ 50 mm; the bottom of the passivation liquid collection box is provided with a certain slope A, A = 1 ~ 3 degrees;

[0032] 5) Use the exhaust system to achieve a certain negative pressure inside the passivation liquid collection box to prevent the leakage of fine particles of the aerosol passivation liquid. The air volume of the exhaust system

[0033] 6) The air extracted by the air extraction system is separated in the passivation liquid separation tank, the separation mode is a coalescence type gas-liquid separator, the air volume of the separator is consistent with the air volume Q of the air extraction system, the separated liquid is returned to the passivation liquid collection tank, and the tail gas after separation is introduced into the exhaust system.

[0034] It should be noted that the above embodiments are not intended to limit the scope of protection of the present application, and any equivalent transformations or substitutions made on the basis of the above technical solutions fall within the scope of protection of the claims of the present application.

Claims

1. A recovery system for aerosol spraying chromium-free passivation liquid, characterized in that: The recovery system includes a passivation liquid dispensing tank, a passivation liquid collecting tank, a passivation liquid separation tank, a passivation liquid aerosol nozzle, a passivation liquid intercepting mechanism, a redundant passivation liquid collecting mechanism, a passivation liquid collecting box, a jet pressure pump and a filter. The passivation liquid dispensing tank is connected to the passivation liquid aerosol nozzle through the filter and the jet pressure pump. A passivation liquid intercepting mechanism is provided between the passivation liquid aerosol nozzle and the tinplate. A redundant passivation liquid collecting mechanism is provided opposite the passivation liquid intercepting mechanism and the tinplate. The redundant passivation liquid collecting mechanism is connected to the passivation liquid collecting box. The passivation liquid collecting box is connected to the passivation liquid collecting tank. The passivation liquid separation tank is connected to the passivation liquid collecting box. The passivation liquid separation tank is connected to the passivation liquid collecting tank. The passivation liquid collecting tank is connected to the passivation liquid dispensing tank. The passivation liquid retaining mechanism is used to retain the passivation liquid in the edge atomization zone of the fluid sprayed by the aerosol nozzle. The passivation liquid retaining mechanism consists of a baffle (51), a liquid receiving trough (52) and a liquid receiving reflux trough (53). The width of the flow area on the baffle is W and the height is H. The distance between the aerosol nozzle and the tinplate is L1. The distance between the passivation liquid retaining mechanism and the nozzle is L2 = (1 / 2 to 3 / 4) L1. The width W of the flow area is 1.1 to 1.2 times the width of the tinplate. The width W1 of the baffle is W1 = (1.05 to 1.2) W. The height H of the flow area is related to L1, H = (1 / 3 to 1 / 2) L1. The upper edge of the baffle is provided with a liquid receiving trough. The passivation liquid collected by the liquid receiving trough flows into the passivation liquid retaining mechanism through the reflux trough.

2. The recovery system of the aerosol spray chromium-free passivation liquid according to claim 1, characterized in that: The passivation liquid in the passivation liquid preparation tank is sent to the passivation liquid aerosol nozzle by the injection pressure pump through the filter, the passivation liquid sprayed from the passivation liquid aerosol nozzle is sprayed onto the surface of the tinplate after passing through the passivation liquid intercepting mechanism, the redundant passivation liquid collecting mechanism collects the redundant passivation liquid sprayed onto the opposite side of the tinplate, the passivation liquid collected by the passivation liquid intercepting mechanism and the redundant passivation liquid collecting mechanism flows back to the passivation liquid collecting box, the excess aerosol liquid particles in the passivation liquid collecting box are separated into gas and liquid by the passivation liquid separation tank, the tail gas is discharged through the exhaust system, and the obtained liquid flows back to the passivation liquid collection tank.

3. The recovery system of the aerosol spray chromium-free passivation liquid according to claim 2, characterized in that: The redundant passivation liquid collection mechanism is arranged on the back of the spraying surface of the tinplate. The width W1 of the redundant passivation liquid collection mechanism is equivalent to the width of the passivation liquid retention mechanism. The window width W of the redundant passivation liquid collection mechanism is equivalent to the width of the retention mechanism. The height H1 of the retention mechanism is (1.1 to 1.3) times the H in the retention mechanism. A stainless steel wire mesh placed at 45° is arranged inside the retention mechanism. The stainless steel wire mesh can realize gas-liquid separation of the aerosol liquid particles sprayed onto the mesh.

4. The recovery system of the aerosol spray chromium-free passivation liquid according to claim 3, characterized in that: The passivation liquid aerosol nozzle, the passivation liquid interception mechanism and the redundant passivation liquid collection mechanism are placed in the passivation liquid collection box. The passivation liquid collection box is a square structure. Two narrow slits are respectively provided at the corresponding positions in the middle of the upper and lower parts of the passivation liquid collection box. The width of the narrow slit T is 60 to 120 mm, and the length of the narrow slit is the same as the width W of the passivation liquid interception mechanism. An exhaust port is provided above the passivation liquid collection box. The exhaust port is circular. Its diameter D is related to the width and length of the narrow slit. The diameter A drain port is provided at the bottom of the passivation liquid collection box, and the diameter of the drain port is DN=20-50mm; the bottom of the passivation liquid collection box is provided with a certain slope A, A=1-3°.

5. The recovery system of the aerosol spray chromium-free passivation liquid according to claim 4 is characterized in that: The passivation liquid collection box is equipped with an exhaust system. The air volume Q of the exhaust system is determined by the length and width of the narrow slit on the box. The air extracted from the box is separated by a coalescing gas-liquid separator. The air volume processed by the separator is consistent with the air volume Q of the exhaust system. The separated liquid flows back to the passivation liquid collection box, and the separated tail gas enters the exhaust system.

6. A method for recovering chromium-free passivation liquid by mist spraying, characterized in that Using the recovery system according to any one of claims 1 to 5, the method is as follows 1) The passivation liquid in the passivation liquid dispensing tank is sent to the passivation liquid aerosol nozzle by the spray pressure pump through the filter, the passivation liquid sprayed from the passivation liquid aerosol nozzle is sprayed onto the surface of the tinplate after passing through the passivation liquid intercepting mechanism, the redundant passivation liquid collecting mechanism collects the redundant passivation liquid sprayed onto the opposite side of the tinplate, the passivation liquid collected by the passivation liquid intercepting mechanism and the redundant passivation liquid collecting mechanism flows back to the passivation liquid collecting tank, the excess aerosol liquid particles in the passivation liquid collecting tank are separated into gas and liquid by the passivation liquid separation tank, the tail gas is discharged through the exhaust system, and the obtained liquid flows back to the passivation liquid collecting tank; 2) The passivation liquid retention mechanism is used to intercept the passivation liquid in the edge atomization zone of the fluid sprayed from the aerosol nozzle. The passivation liquid retention mechanism consists of a baffle, a liquid receiving trough, and a liquid receiving reflux trough. The width of the flow area on the baffle is W and the height is H; the distance between the aerosol nozzle and the tinplate is L1; the distance between the passivation liquid retention mechanism and the nozzle is L2 = (1 / 2 to 3 / 4) L1, the width W of the flow area is 1.1 to 1.2 times the width of the tinplate, the width W1 of the baffle is W1 = (1.05 to 1.2) W, the height H of the flow area is related to L1, H = (1 / 3 to 1 / 2) L1, and a liquid receiving trough is provided on the upper edge of the baffle. The passivation liquid collected in the liquid receiving trough flows into the passivation liquid retention mechanism through the reflux trough; 3) A redundant passivation liquid collection mechanism is provided on the back of the spraying surface of the tinplate. The width W1 of the redundant passivation liquid collection mechanism is equivalent to the width of the passivation liquid interception mechanism. The window width W of the redundant passivation liquid collection mechanism is equivalent to the width of the interception mechanism. The height H1 of the interception mechanism is 1.1 to 1.3 times the height H of the interception mechanism. A stainless steel wire mesh placed at a 45° angle is provided inside the interception mechanism. The stainless steel wire mesh can separate the aerosol liquid particles sprayed onto the mesh into gas and liquid. 4) The passivation liquid aerosol nozzle, the passivation liquid interception mechanism and the redundant passivation liquid collection mechanism are placed in the passivation liquid collection box. The passivation liquid collection box is a square structure. Two narrow slits are respectively provided at the corresponding positions in the middle of the upper and lower parts of the passivation liquid collection box. The width of the narrow slit T is 60 to 120 mm, and the length of the narrow slit is equivalent to the width W of the passivation liquid interception mechanism. An exhaust port is provided above the passivation liquid collection box. The exhaust port is circular. Its diameter D is related to the width and length of the narrow slit. The diameter A drain port is provided at the bottom of the passivation liquid collection box, and the diameter of the drain port is DN = 20 ~ 50 mm; the bottom of the passivation liquid collection box is provided with a certain slope A, A = 1 ~ 3 degrees; 5) Use the exhaust system to achieve a certain negative pressure inside the passivation liquid collection box to prevent the leakage of fine particles of the aerosol passivation liquid. The air volume of the exhaust system 6) The air extracted from the exhaust system is separated in the passivation liquid separation tank. The separation method is a coalescing gas-liquid separator. The air volume processed by the separator is consistent with the air volume Q of the exhaust system. The separated liquid flows back to the passivation liquid collection box, and the separated tail gas enters the exhaust system.

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