JP2005133238A - Method for improving yield of ash in waste paper reclaimed pulp and paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for improving the yield of ash in waste paper reclaimed pulp to enable discharge tailings and filler use to be reduced. <P>SOLUTION: The method for improving the yield of ash in waste paper reclaimed pulp comprises the following steps: In the step of feeding the waste paper reclaimed pulp from its receiving chest to its compounding chest, the cation demand of the waste paper reclaimed pulp is automatically measured with a relevant measuring instrument 15, and according to the measurement, an appropriate amount of a coagulant 16 is added to the waste paper reclaimed pulp prior to feeding it to the compounding chest to effectively coagulate anion trash-containing ash in the waste paper reclaimed pulp. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for improving the ash content yield of recycled paper recycled pulp and paper using the recycled recycled paper pulp to which the method is applied.

  In the papermaking process, control factors for stabilizing the wet end that handles wet raw materials include raw material concentration, freeness, ion concentration, ash content, and first pass retention. In addition, it is considered effective to control the potential (cation demand value) of the raw material slurry for stabilization of the wet end. Examples of chemicals for adjusting the potential of the raw material slurry include sulfuric acid band, cationized starch, and coagulant. Widely used. It is also known to measure the potential of the raw slurry, adjust the concentration of the additive chemical in the pulp slurry according to the measured value, and adjust the potential of the raw slurry to a potential suitable for papermaking purposes (for example, , See Patent Document 1).

The potential (cation demand value) of the raw slurry is the total charge of the anionic substance, and the anionic substance (anionic trash) is pulp (including fine fibers), filler (calcium carbonate, talc, etc.) These are negatively charged substances such as various additive chemicals (pigments, sizing agents, antifoaming agents, etc.).
JP 7-286984 A

  By the way, in the present situation, the yield improvement by the addition of a coagulant or the like is not performed in the process for producing recycled paper recycled pulp and the process for receiving and blending recycled paper in a paper machine. Therefore, there is a problem in that the ash yield of recycled paper recycled pulp is low, which increases the amount of waste generated in the recycled paper recycled pulp manufacturing process, while a new filler must be used.

  In view of the above-described conventional problems, the present invention improves the ash content of recycled paper pulp, which can improve the yield of ash in recycled pulp and reduce the amount of waste and the amount of filler used. It is an object to provide a method and paper to which the method is applied.

  The method for improving the ash content yield of recycled paper pulp according to the present invention is a method in which the cation demand of recycled paper recycled pulp is cationized in a process of supplying recycled paper recycled pulp to a compounded chest from an acceptance chest of recycled paper recycled from a recycled paper recycling process. It is automatically measured with a demand measuring instrument, and a coagulant is added to the recycled paper pulp before supplying it to the blended chest according to the measurement result.

  According to this configuration, in the process of supplying waste paper recycled pulp from the recycled paper receiving chest to the blended chest, an appropriate amount of a coagulant is added to the waste paper recycled pulp according to the cation demand measurement result. As a result, the ash content of the anion trash can be effectively condensed, and as a result, the yield of ash content of recycled paper recycled pulp can be improved, and the amount of discharged soot and the use of a new filling amount can be reduced.

  In addition, when the amount of the coagulant added is controlled according to the difference between the preset cation demand value and the measured value, feedback control is performed so that the target cation demand value is obtained, so that the above-described effects can be stably achieved. it can.

  In addition, by adding a coagulant after the physical force from the feeding pump that supplies recycled paper from the receiving chest to the blended chest is added, it is possible to prevent the coagulation from being dissociated by the physical force, and the above effects Can be played reliably.

  In addition, the present invention provides a paper slurry having a cation demand value of 0 to 0.2 meq when paper is made using the recycled paper recycled pulp produced by the above-described method for improving the ash content yield of recycled paper and is re-disaggregated after the paper making. And paper having a measured ash content of 5% or more, which is made using the above recycled paper recycled pulp and baked at 550 ° C.

  According to the present invention, in the step of supplying recycled paper pulp from the receiving chest of recycled paper recycled pulp to the blended chest, an appropriate amount of a coagulant is added to the recycled recycled paper pulp according to the measurement result of the cation demand. As a result, it is possible to improve the yield of ash and reduce the amount of discharged soot and the amount of new filling.

  Hereinafter, an embodiment of the method for improving the ash yield of recycled paper recycled pulp according to the present invention will be described in detail with reference to FIGS.

  In FIG. 1, recycled paper recycled pulp (DIP) 1 is mixed with raw materials in a DIP chest 2 that receives DIP, is made into a DIP slurry, and is supplied to a blending chest 3 by a flow pump 4. Moreover, various pulp raw materials, such as KP or TMP, machine broke, and GP, are combined with an appropriate blending ratio and supplied directly to the blending chest 3 as necessary. The raw material slurry blended and prepared in the blending chest 3 is supplied to the machine chest 7 and then guided to the seed box 8, and the raw material slurry adjusted here passes through the cleaner 9, the pump 10, and the screen 11. Via the stock inlet 12 to the wire part 14 of the paper machine 13.

  In the process of introducing the DIP slurry from the DIP chest 2 to the blending chest 3, the cation demand value of the DIP slurry is measured by the online cation demand measuring device 15, and the addition adjustment valve 17 is controlled to open and close based on the measured value. The amount of the coagulant 16 added to the DIP slurry fed from the chest 2 to the blended chest 3 is controlled.

  Further, the addition place of the coagulant to the DIP slurry is set on the downstream side of the feed pump 4 that feeds the DIP slurry from the DIP chest 2 to the blending chest 3, and the coagulant is added to the DIP slurry after the coagulant is added. It is comprised so that the physical force by the feed pump 4 may not be added.

  As the cationic coagulant 16, PAM (polymer acrylamide), PDADMAC (polydadmac), pAm (polyamine), PEI (polyethyleneimine) and the like are preferably applied.

  The online cation demand measuring instrument 15 is not particularly limited, but PCT15 or PCT20 (manufactured by Mutek) is suitable as a result of the research up to now. This cation demand meter introduces the stock into the cell of the meter and causes the sample liquid to flow between the cell cylinder and the piston by the operation of the upper and lower pistons. The charge requirement is measured by polyelectrolyte measurement by utilizing the fact that the colloidal dissolved substance particles in the pulp suspension are charged with ions. Is.

  In the process of supplying the raw slurry from the seed box 8 to the wire part 14, it is desirable to measure the freeness and perform the freeness control.

  Next, the addition control operation of the coagulant 16 for improving the ash yield of the above recycled paper recycled pulp will be described with reference to FIG. First, the cation demand value of the DIP slurry is measured by the cation denmand measuring device 15 (step S1), and then the difference between the measured cation demand value and a preset target cation demand value is calculated (step S2). The target cation demand value is set by experimentally obtaining in advance a cation demand value that can ensure the yield of ash content of recycled paper. Next, an increase / decrease amount of the addition amount of the coagulant 16 is calculated according to a predetermined arithmetic expression according to the difference between the measured value and the target value (step S3). Note that the calculation may be made with reference to a table stored in the memory instead of the calculation based on the calculation formula. Next, a command is output to the addition adjustment valve 17 so that the addition amount of the coagulant 16 obtained by the calculation is obtained (step S4).

  Thus, according to this embodiment, by adding an appropriate amount of a coagulant to the recycled paper pulp according to the measurement result of the cation demand, the ash containing anionic trash in the recycled paper pulp can be effectively condensed. As a result, it is possible to improve the yield of ash in recycled recycled paper, and to reduce the amount of discharged soot and the amount of new filler used.

  Next, some examples and comparative examples of the present invention will be described.

  In the paper making process using recycled paper (DIP) recycled using 65% of used leaflet paper and 35% colored paper, the cation demand value of the DIP slurry between the DIP chest 2 and the blended chest 3 According to the measurement results, as shown in Table 1, as Examples 1 to 5, a coagulant of PAM, PDADMAC, pAm, or PEI is added to the DIP slurry, and a required amount of filler is further added. Addition to make LWCP (Low Weight Coated Paper). Further, as Comparative Example 1, LWCP was similarly made without adding a coagulant to the DIP slurry.

  And the yield (%) of the ash content of each Example 1-5 and the comparative example 1, SS content (ppm) in filtrate, and the addition amount of the filler for making LWCP were calculated | required. In addition, the suitability of drainage and the cost of coagulant were evaluated, and the total merit was judged. The results are shown in Table 1.

なお、排水の良否評価は、濾水ＳＳ含有量が２００〜２５０ｐｐｍ未満の場合は◎、２５０〜３５０ｐｐｍの場合は○、それ以上は×とした。また、凝結剤費は、薬品単価と添加量の積で求め、相対的に安価のものを◎、中間のものを○、相対的に高価となったものを△として、相対評価を行った。また、トータルメリットは填料の削減と凝結剤費の増加と排水処理のコストの変化を見積もり、◎と○と×の３者に相対的に分類評価した。

In addition, the quality evaluation of the waste water was evaluated as “◎” when the drainage SS content was less than 200 to 250 ppm, “◯” when 250 to 350 ppm, and “x” when it was higher. Further, the coagulant cost was determined by multiplying the chemical unit price and the amount added, and the relative evaluation was performed by assuming that the relatively inexpensive one was ◎, the middle one was ○, and the relatively expensive one was △. In addition, the total merit was estimated by estimating the reduction of filler, increase of coagulant cost, and change of wastewater treatment cost, and categorized and evaluated relative to ◎, ○ and ×.

  From Table 1, as shown in Examples 1 to 5, when any coagulant is added, the ash content yield is improved from 52% to 55% or more as compared with Comparative Example 1, and the filtrate is accordingly accompanied. The SS content can be reduced from 400 ppm to 350 ppm or less, and the amount of filler added to make the same LWCP can be reduced from 37 kg / t to 32-34 kg / t. It can be seen that it is very expensive to reduce the amount of filler used. In addition, from the comparison between Examples 4 and 5, by adding the coagulant addition site after the feed pump 4, the ash content yield can be 56% or more and the SS content of filtrate can be 250 ppm or less. It turns out to be effective.

  The method for improving the ash content yield of recycled paper pulp according to the present invention comprises adding an appropriate amount of a coagulant to the recycled paper pulp according to the measurement result of the cation demand of the recycled paper pulp. It is useful for paper-making products using all recycled recycled paper, because it can effectively condense and improve the yield, and reduce the amount of discharged soot and the amount of new filling.

It is a schematic block diagram of the paper making process using the used paper recycled pulp in one Embodiment of this invention. It is an addition control flow figure of a coagulant with respect to used paper recycled pulp in the embodiment.

Explanation of symbols

1 Waste paper recycled pulp (DIP)
2 DIP chest 3 Compounding chest 4 Flow pump 15 Cation demand measuring device 16 Coagulant 17 Addition regulating valve

Claims (5)

  In the process of supplying used paper recycled pulp to the compounding chest from the used paper recycled pulp receiving chest sent from the used paper recycling treatment process, the cation demand of the used paper recycled pulp is automatically measured with a cation demand measuring device, and the measurement result is A method for improving the ash content of used recycled paper pulp, comprising adding a coagulant to the recycled paper pulp before supplying it to the blended chest.   2. The method for improving the ash content yield of used paper recycled pulp according to claim 1, wherein the addition amount of the coagulant is controlled in accordance with a difference between a preset cation demand value and a measured value.   The method for improving the ash content yield of used paper recycled pulp according to claim 1 or 2, wherein a coagulant is added after a physical force is applied by a feed pump for supplying the recycled paper from the receiving chest to the blended chest.   The cation demand value of the pulp slurry when paper is made using the recycled paper recycled pulp manufactured by the method for improving the ash yield of the recycled paper pulp according to any one of claims 1 to 3, and the pulp slurry is re-disaggregated after the paper making is 0 to Paper characterized by 0.2 meq.   The measured ash content produced by using the recycled paper pulp produced by the method for improving the ash content yield of the recycled paper pulp according to any one of claims 1 to 3 and calcined at 550 ° C is 5% or more. Characteristic paper.

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