Submerged membrane filtration system and process for removing suspended solid from phosphating liquid

Abstract

The invention discloses a submerged membrane filtration system for removing a suspended solid from phosphating liquid. The submerged membrane filtration system comprises a membrane tank, a membrane module, a backwash tank, a liquid feed pump, a circulating pump, an air blower, a paper filter, a self sucking pump, a backwash pump and a programmable controller, wherein the membrane module is a submerged hollow fibrous membrane module; and in a process of the system, external pressure suction membrane filtration is performed under variable frequency constant current control or variable frequencyconstant pressure, and membrane cleaning is performed according to automatic sequences, wherein the membrane cleaning procedure comprises gas-water backwashing and chemical cleaning. The invention has the advantages that: the submerged membrane filtration system can remove suspension from the phosphating liquid, the content of the suspended solid (SS) in the filtered liquid is low, free acid, total acid and a promoter are not changed, the phosphating effect is good, the operation is simple, the automation degree is high, the service life is long and the energy consumption is low; and the system can be connected with the conventional phosphating liquid treatment system in a phosphating section of a pretreatment production line for on-line use to purify the phosphating liquid in real time, and also can independently treat the waste phosphating liquid for recycle.

Description

technical field [0001] The invention relates to the treatment technology of phosphating solution in the pretreatment of automobile coating, in particular to a submerged membrane filtration system and process for removing suspended matter in the phosphating solution. Background technique [0002] With the increasing development of automobile coating technology, its technological process is also developing rapidly. Now it represents the highest level of automobile coating. The most typical process route is: pretreatment-cathode electrophoretic primer-drying-sealant (drying)-spray paint-drying-spray topcoat-spray varnish (wet on wet)-drying. [0003] The position of pre-treatment in automobile painting is very important. Painting is an economical and effective method of corrosion resistance and decoration for automobiles. As the first process of automobile painting, the quality of the pre-treatment is an important link that directly affects the service life of the coating and...

AI Technical Summary

Problems solved by technology

[0016] The belt-type automatic filtration device has a high degree of automation and can be produced continuously. The disadvantage is that filter paper with particularly high tensile strength is required. The filter paper is mixed with the residue, which is not conducive to the recycling of phosphating residue.

[0017] The above methods are mainly used to remove the phosphating residues accumulated in the phosphating solution, and they are helpless to the fine particles that have a fatal impact on the surface coating quality, and it is difficult to fundamentally solve the problem of hanging dust on the surface of the plated parts

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