JP2005248386A - Method for producing waste paper pulp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for stabilizing ash ratio in waste paper pulp. <P>SOLUTION: The invention relates to the method for producing waste paper pulp comprising a process disintegrating waste paper, a dust removing process, a bleaching process, a deinking process and a washing process, wherein recycled filler with ≥80% of brightness which is obtained by dehydrating/burning/pulverizing floss generated in the deinked pulp producing process or filler contained in the waste water, is added to the feeding raw material with water to obtain the waste paper pulp with 8-30% of ash ratio. In the process, 8-30% of the ash ratio is achieved by measuring the ash ratio in the feeding raw material with water by on-line ash ratio measuring apparatus and setting the ash ratio required by a paper machine based on the measured value and then adding the recycled filler. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing waste paper pulp, and more specifically, the production of waste paper pulp that facilitates the adjustment of paper ash content in the paper making process by adding an appropriate amount of recycled filler to the ash content in the raw material. Regarding the method.

  In recent years, from the viewpoint of saving wood resources and recycling paper, printed paper (magazine waste paper, newspaper waste paper, etc.) is often used as a pulp raw material. In addition, the waste paper pulp has an increased ash content such as an internal filler in the raw waste paper and a pigment derived from the coated paper. Waste paper pulp is manufactured in accordance with the steps of disaggregation, dust removal, bleaching, deinking and washing, regardless of the ash content of the waste paper raw material.

  In the production of conventional deinked pulp, when it is necessary to lower the ash content of the product pulp, it is common to incorporate an ash removal step during any of the above steps or in the final step. However, even this cannot prevent the generation of residual ash.

  In addition, when the waste paper pulp is produced by blending many types of waste paper, the ash content rate of the feedstock is unstable. Even if trying to adjust the ash content by changing the ratio of used paper, the time lag is large, and in most cases it does not lead to stability. For this reason, when many types of waste paper are used as raw materials in the conventional methods for producing waste paper pulp, the residual ash content in the feed material changes, and the ash content adjustment is not performed smoothly in the paper preparation process. There was an unresolved issue.

  An object of the present invention is to facilitate adjustment of paper ash content in the paper preparation process by controlling the content ash content of the feed material even in waste paper pulp using many types of used paper.

  The said subject is achieved by following (1) (2) (3).

(1) In the method of manufacturing waste paper pulp, which comprises the steps of disaggregating, dedusting, bleaching, deinking, and washing waste paper, the filler contained in the floss or waste water generated from the deinked pulp manufacturing process is dehydrated in the feed material. A method for producing waste paper pulp, characterized by adding a regenerated filler having a whiteness of 80% or more obtained by firing and pulverizing to make the ash content 8% to 30% or more.

(2) The method for producing waste paper pulp as described in (1) above, wherein the ash content in the feed material is measured with an on-line ash content measuring machine.

(3) Measure the content ash content in the feed material with an online ash content measuring machine, set the ash content required by the paper machine based on the measured value, and then add the recycled filler, The method for producing waste paper pulp as described in (1) above, wherein the ash content is 8% to 30%.

  According to the invention of claim 1, based on the ash content in the feed material, a necessary amount of recycled filler having a whiteness of 80% or more from the deinking sludge is added to the feed material, thereby containing the feed material. The ash content is stable and the paper ash content can be adjusted easily and accurately in the paper preparation process. Furthermore, since the recycled filler to be added has a whiteness of 80% or more, the whiteness of the product pulp is high, and when this is used as a papermaking raw material, a recycled paper with a high whiteness can be obtained.

  According to the invention of claim 2, by measuring the amount of ash in the feed material online, it is possible to grasp the change in the ash content in real time even when many types of used paper are used.

  According to the invention of claim 3, the amount of ash in the feed material is measured online, and by adding a necessary amount of recycled filler based on this measured value, even when many types of used paper are used, Waste paper pulp having a constant ash concentration is obtained.

  The present invention is described in further detail below.

  The present invention relates to a method for producing waste paper pulp comprising the steps of disaggregation, dust removal, bleaching, deinking, and washing waste paper, and a recycled filler having a whiteness of 80% or more (Tappi-534 pm-76 method) in the feed material. The ash content is to be added so as to be 8% to 30%.

  The term “recycled filler” as used herein refers to a filler having a whiteness of 80% or more by finely pulverizing a filler obtained by dehydrating and baking-extracting papermaking sludge, such as floss of waste paper pulp manufacturing process or wastewater / drainage sludge. White pigment). The regenerated filler preferably has a particle size under 2 μm of 80% or more, and more preferably a particle size under 2 μm of under 90%.

  This white pigment was obtained, for example, by the method previously proposed by the present inventors in Japanese Patent Application No. 2000-362801, that is, by forming papermaking sludge and then incineration (preferably incineration at 500 to 1000 ° C.). The incinerated ash can be obtained by pulverizing (preferably pulverizing so as to have an average particle size of 0.1 to 10 μm).

  Further, the white pigment is produced by the method proposed in Japanese Patent Application No. 2003-206499 as described above, that is, the papermaking sludge is dried and the dried sludge is burned (preferably at 700 ° C. or less and within a burning time of 10 seconds. A primary combustion product containing unburned matter is obtained by combustion, and this is subjected to secondary combustion until a predetermined whiteness is achieved while promoting contact with oxygen by stirring (preferably at a temperature of 700 ° C. or less and a combustion time of 1 Burned within hours).

  Further, the white pigment is mixed with the method proposed in Japanese Patent Application No. 2003-206500 in the same manner as described above, that is, by mixing calcium carbonate particles (preferably using calcium carbonate derived from waste) with the burned particles of paper sludge. Can be obtained as a mixture of In this case, (i) at least one of the combustion product particles, calcium carbonate particles and a mixture thereof is produced by wet pulverization in a high concentration slurry having a concentration of 50% by weight or more to which a dispersant is added. Preferably, or (ii) the combustible particles are first pulverized and the particle size is substantially matched with or close to the particle size of the calcium carbonate particles, then mixed with the calcium carbonate particles and subjected to secondary pulverization. It is preferable to manufacture according to a particle size.

  In the disaggregation step in the method for producing waste paper pulp of the present invention, raw paper waste and dilution water are added so that the solid content concentration is 5 to 30%, and further a chemical (sodium hydroxide) is added to 0.1 to 0.5% by weight of pulp. , Preferably 0.1 to 0.3% by weight, a raw paper disintegration step of disaggregation at a disaggregation time of 5 to 30 minutes and a disaggregation temperature of 46 to 70 ° C, preferably 46 to 50 ° C Moreover, you may add 0.02-0.1% of deinking agents with respect to a pulp at a disaggregation process.

  In the present invention, if necessary, the waste paper raw material disaggregated in the disaggregation step may be transferred to the ash removal step, and then transferred to the removal step. This ash content removing step is a cleaning step for preferentially removing ash content in the raw material, and can be generally performed using an existing apparatus such as an extractor, a fall washer, or a double nip thickener. Here, the ash content is preferably reduced to 10 to 25% by weight in the total solid content.

  The removal process is a process of removing foreign substances in the raw material with a slit screen, a screen cleaner or the like.

  A bleaching process is a process of whitening a pulp using a chemical | medical agent. In general, used paper recycling uses hydrogen peroxide, hydrosulfide, thiourea dioxide, hypo, and the like. The hydrogen peroxide bleaching step is 1 to 3 wt% hydrogen peroxide (vs. pulp), 0.3 to 1.5 wt% sodium hydroxide (vs pulp), 1 to 3 wt% sodium silicate (vs pulp) The bleaching time is 1 to 4 hours, the bleaching pulp concentration is 20 to 30%, and the bleaching temperature is 70 to 80 ° C.

  The deinking step is a step of removing ink out of the system by adsorbing ink to air with a flowmeter. The treatment concentration in the floatator is 1.0 to 1.5%, the treatment temperature in the floatator is 20 to 50 ° C., preferably 35 to 45 ° C., and the deinking agent is 0.02 to 0.05 pulp. It is carried out with addition by weight%. Further, when a deinking agent is added in the disaggregation step, it may not be added.

  The washing step is a step of washing the used paper pulp after the deinking step by diluting with a large amount of water.

  In the present invention, prior to the addition of the regenerated filler, the ash content in the feed material is measured in real time by an on-line ash meter. Then, the measured value is fed back to the regenerated filler adding means, and a necessary amount of the regenerated filler is added to the feed material to stabilize the ash content. Note that the ash measurement may be either continuous or intermittent.

  As an online ash content measuring device, for example, RMI manufactured by Metso Automation or AC-5000 manufactured by BTG is used. The measurement principle of the former ash content measuring instrument RMI is to extract the raw material from the sampling pipe, dilute it to about 1% with a dilution unit, and measure with a retention monitor. Sample the laser light and xenon light from the measuring instrument. Is measured by the amount of attenuation and backscattered light.

  The installation position of the online ash measuring device, that is, the position of extracting the raw material from the sampling pipe may be anywhere before the regenerated filler is added to the feed material, but if an ash removal process is provided if necessary It is a stage after this process.

  The recycled filler is added in such an amount that the ash content of the waste paper pulp produced by adding the recycled filler is in the range of 8 to 30%. The reason why the ash content of the waste paper pulp produced is 8-30% or more is that when using waste paper normally, the ash content in the pulp produced in the waste paper pulp process is at least 8% in the current equipment, and below this This is because, in the case of paper made with 100% used paper, if the ash content is 30% or more, paper making is difficult.

  The amount of recycled filler added varies depending on the type of used paper, or several types of used paper are used for recycled pulp at the same time. Since an appropriate amount of recycled filler is added, the ash content of the manufactured waste paper pulp is kept almost uniform. In addition, the place where this regenerated filler is added may be anywhere after the sampling pipe for online ash measurement.

  In the present invention, it has been described that all fillers added to waste paper pulp are recycled fillers. However, it is possible to substitute a part of the recycled fillers with the original fillers as necessary.

  Next, the present invention will be described more specifically with reference to examples.

(Manufacture of recycled filler 1)
Paper sludge obtained by dehydration to 55 to 65% in a DIP floater floss or dewatering equipment is incinerated at a temperature of 700 ° C. in an incinerator, and the generated incinerated ash has an average particle size of 0.1 to 10 μm. The mixture was pulverized to obtain a white pigment (recycled filler 1) having a whiteness of 80%. The whiteness was measured using a powder whiteness meter (type C-100) manufactured by Kett Science Laboratory. (same as below)

(Manufacture of recycled filler 2)
Using the same papermaking sludge as recycled filler 1, the dried sludge dried to a moisture content of 15% by a dryer is burned in a primary combustion furnace (combustion temperature 600-700 ° C., residence time less than 10 seconds) to obtain a combustion product, Further, this combustion product was burned in a secondary combustion furnace (combustion temperature 600 to 700 ° C., residence time 1 hour) to obtain a combustion product (recycled filler 2) having a whiteness of 81% or more and an average particle size of 500 μm.

(Manufacture of recycled filler 3)
Deinked sludge combustion product particles with an average particle size of 100 μm and whiteness of 85% are made into a high concentration slurry with a concentration of 65% by weight. A dispersant is added to this and wet pulverized to an average particle size of 20 μm while blowing gas with a pulverizer. Next, waste calcium carbonate particles having an average particle diameter of 5 to 20 μm and whiteness of 90% or more associated with kraft pulp production are mixed with the pulverized particles at a weight ratio of 1: 1, and this mixture is supplied to a stirring tank. The mixture was mixed while blowing carbon dioxide gas, and the mixture was wet pulverized to obtain calcium carbonate mixed combustion particles (recycled filler 3) having a 2 μm under 90% or more and a whiteness of 85% or more.

(Example 1)
Various types of used printed paper (2% with low ash content, 40% with high ash content) 100% raw material is charged intermittently into the pulper 18% raw material concentration, sodium hydroxide addition rate (vs pulp) 0.3% The disaggregation time was 25 minutes and the disaggregation temperature was 50 ° C. (disaggregation step).

After the disaggregation, the disaggregated raw material was diluted to 5% (dilution step), then introduced into an ash removal device and concentrated to a raw material concentration of 15% (ash removal step). The filtrate (solid content 2%) of the ash removal device was treated with a filtrate treatment device to obtain treated water having a solid content concentration of 0.1% or less. This treated water was used as dilution water in the used paper disaggregation process, washing water for the ash removal apparatus in the ash removal process, and washing water in the pulp washing process after deinking described later.
After removing the ash, the dust was removed with a dust removal device (dust removal process).

  The pulp slurry after dust removal was diluted to 1%, then processed with a deinked pulp manufacturing device, and further processed with a cleaning device to produce a product pulp (bleaching, deinking, and cleaning steps). The bleaching conditions were: hydrogen peroxide addition rate (vs. pulp) 1.5%, sodium hydroxide (vs. pulp) 0.5%, sodium silicate addition rate (vs. pulp) 1.0%, pulp concentration 25%, bleaching time 2 hours at a bleaching temperature of 70 ° C. The deinking conditions were as follows: the concentration of the floater treatment was 1%, the flowmeter treatment temperature was 45 ° C., and the deinking agent addition rate was 0.02%. A higher alcohol deinking agent was used as the deinking agent.

  A means for adding a regenerated filler was provided after the flotator treatment. Further, an on-line ash content measuring device (RMi, manufactured by Metso Automention Co., Ltd.) was provided immediately after the regenerative filler addition facility. The value measured by this online ash meter is fed back to the recycled filler adding means, and the recycled filler is fed by the adding means so that the ash content of waste paper pulp is set to 15% (optionally set to 8-30%). It is added to the raw material.

  In this used paper pulp manufacturing method, when recycled filler 1 was used as a recycled filler, the ash content was stable at 15%, and used paper pulp having a whiteness of 80% (measured by JIS P 8148) was obtained.

(Example 2)
In Example 1, recycled paper pulp was produced in the same manner as in Example 1 except that the recycled filler 2 was used instead of the recycled filler 1 as the recycled filler. The obtained waste paper pulp had a stable ash content of 15% and a whiteness of 81.0% (measured by JIS P 8148).

(Example 3)
In Example 1, recycled paper pulp was produced in the same manner as in Example 1 except that the recycled filler 3 was used instead of the recycled filler 1 as the recycled filler. The obtained waste paper pulp had a stable ash content of 15% and a whiteness of 82.5% (measured by JIS P 8148).

Claims (3)

  In the method of manufacturing waste paper pulp consisting of the steps of disaggregating, dedusting, bleaching, deinking and washing waste paper, the floss generated from the deinked pulp manufacturing process or the filler contained in the wastewater is dehydrated, calcined, A method for producing waste paper pulp, comprising adding a recycled filler having a whiteness of 80% or more obtained by fine pulverization to an ash content of 8% to 30%.   The method for producing waste paper pulp according to claim 1, wherein the ash content rate in the feed material is measured with an on-line ash content measuring machine. Measure the ash content in the feed material with an on-line ash meter, set the ash content required by the paper machine based on the measured value, and then add the recycled filler to determine the ash content. The method for producing waste paper pulp according to claim 1, wherein the content is 8% to 30%.