Technique of accurate micropores film for filterning salt water in use for making alkali

Abstract

A precise millipore thin-layer filtering process for the saline used to prepare alkali includes filtering the raw salination by precise millipose filtering until the thickness of filtered cake reaches 0.5-2 mm, introducing the compressed air to the filter for reversely blowing the filter tubes, cyclically repeating said two steps, discharging filtered cake, and chemical regeneration.

Description

Technical field [0001] The invention relates to a filtration process of brine for caustic soda production, in particular to a precise microporous thin-layer filtration process in which gas and liquid are blown back together to make a thin filter cake layer fall off and thicken during back blowing. Background technique [0002] The production of alkali or alkaline salt requires brine as a raw material, and the quality of the brine directly affects the quality, yield and cost of the finished product. Impurities in the brine can be removed by using heterogeneous phase separation method and homogeneous phase separation method in series. The heterogeneous separation method mainly includes filtration, sedimentation, air flotation and other methods; the homogeneous separation method mainly includes adsorption, ion exchange and other methods. Among them, filtration is an indispensable and very critical step. [0003] The heterogeneous separation equipment for raw br...

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Problems solved by technology

Flexible filter cloth tubular filter tube, because its capillary pore size will not be very small, it is difficult to efficiently filter out some sub-micron solid particles, and the quality of brine is difficult to guarantee

The flexible microporous membrane tubular filter has high filtration accuracy and can efficiently filter submicron particles. However, due to the relatively low tensile strength of the microporous membrane, high-pressure gas cannot be used for efficient backflush regeneration, and it is easy to clog, It is easy to be damaged, which makes its service life relatively low and the cost of use is quite high; rigid microporous filter tubes are mainly sintered carbon tubes and sintered microporous PE tubes at present. The filter is pre-coated, and it needs to be circulated for a long time during pre-coating, otherwise the filtration accuracy and filtration efficiency are not high, the price of α cellulose is very expensive, the operation cost is high, and the operation is quite troublesome; the carbon tube is also easy to be oxidized in brine Oxidation destroys the microporous structure and deteriorates the filtration performance; microporous PE tube is a new type of filter tube with good mechanical strength and oxidation resistance and low price. The filtration efficiency is high and the filtration speed is fast, but the operation cost is significantly increased, and the operation is more troublesome. If α-cellulose is not used as a filter aid, the capillary diameter of the microporous tube must be small so that Mg(OH) 2 However, the filter cake formed by these colloids and other particles on the surface of the filter tube has a large resistance, resulting in a relatively low average filtration rate.

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