JP2539844B2 - Papermaking White water solids recovery method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a method for recovering a solid content in white water generated from a paper machine.

(B) Conventional Technology Papermaking white water contains a large amount of papermaking raw materials, and solid components in whitewater have been conventionally collected for the purpose of reducing raw material costs and pollution control.

As a solid content recovery method in white water, a filter filtration method or a method in which the solid content in white water is flocculated with a polymer coagulant and then settled or floated is used for recovery. . White water generated from a paper machine is treated by any one of the above methods collectively, although there is a difference in pulp concentration, ash concentration, specific gravity, air content or freeness depending on the generation site. However, it cannot be said that the solid content is efficiently collected.

At the same time, in recent years, the ash concentration in the white water generated from the wire part is becoming higher than that of the white water generated from other parts due to the speeding up of paper machines and the shift to the twin wire former having a top wire.

(C) Problems to be Solved by the Invention In a filter filtration type recovery method, it is necessary to form a premat layer on the surface of the filter mesh, and a large amount of pulp must be added to white water as a sweetener.

Therefore, when recovering the residual raw material in the system for brand change, not only the raw material in white water but also a large amount of pulp raw material added as a sweetener must be collected, and the white water of each part is collectively collected. When processing, it takes a lot of time and a large raw material recovery tank to change raw materials for brand change.

Although the sedimentation method and the flotation type recovery method do not require the addition of sweetener, there is a problem that it is difficult to settle when the ash concentration in white water is low, and it is difficult to float when the ash concentration is high, so it is vulnerable to load fluctuations. However, there was a drawback that it was difficult to support all brands.

In view of the above problems, it is an object of the present invention to provide a most efficient raw material recovery method in white water.

(D) Means for Solving the Problems That is, the present invention provides a method for recovering solid content of papermaking white water, comprising:
This is a method for collecting solid content of white water, which is characterized by accumulating ash concentration of white water of 0.1% or more and that of not, and independently collecting solid content.

Normally, the ash concentration level is
Wire recovery shower, press save all recovery white water,
Also, the white water recovered from the wet part vacuum separator is stable at a low level and is approximately 0.1% or less.On the other hand, the wire white water surplus white water that generates the most amount of water has , But it generally shows a higher level than white water from other parts, that is, 0.1% or more. The intended purpose is achieved independently for these white waters having different ash concentration levels, that is, by an optimum recovery method according to the ash concentration load.

In the present invention, a filter filtration method or a flotation method can be applied to the low ash content white water described above, and a sedimentation method or a filter filtration method can be applied to the ash content high white water described below. However, it is desirable to avoid using the filter filtration method for both of them because there are drawbacks in changing the raw material as described in the section of the problem.

In addition, if one uses a filter filtration method and the other uses a sedimentation method or a floatation method, it is weak against load fluctuations, and if an abnormality occurs in the system of the sedimentation method or the floatation method, a line of a filter filtration method that is strong against water load fluctuation It is possible to stabilize the system by allowing some of the low ash level white water to escape.

Next, an embodiment of the present invention will be described based on the flow of FIG. 1, but the present invention is not limited to this.

(E) Example White water was stratified by a line having an ash concentration of 0.1%. The low ash level white water corresponds to press save all recovered white water, wire recovery shower, and vacuum separator recovered white water, and high ash level white water. Corresponds to the wire backwater surplus white water.

The amounts of the low ash level white water and the high ash level white water were approximately the same, and the low ash level white water was treated by the filter filtration method and the high ash level white water was settled by the sedimentation method.

The flow is shown in FIG. 1 is a filter, 2 is a settling tank, 3 is a tank, and 4 is a pump.

In particular, the filter for low ash level white water treatment can be treated with 35% of the filter area required to treat the total amount of white water, and the amount of sweetener is reduced by that amount, resulting in efficient solid content. I was able to collect it.

(F) Effects of the Invention The effects of the present invention are listed below.

1) Since white water can always be treated by the optimum recovery method, efficient solid content recovery becomes possible.

2) Therefore, the solid content can be collected at a high concentration, and the raw material concentration in the post-process can be easily stabilized.

3) The solid content recovery facility for white water can be downsized, and the running cost can be reduced.

[Brief description of drawings]

 FIG. 1 shows a specific example of the present invention, in which 1 ... Filter 2 ... Sedimentation tank 3 ... Tank 4 ... Pump are shown.

Claims (1)

(57) [Claims] 1. A method for recovering solid content of white water generated from each part of a wet part of a paper machine, wherein the ash concentration of white water is 0.1.
% Or more, and those not, and collect solid content independently of each other.