JP2009262034A - Method of fixing soluble fluorine ion in paper sludge incineration ash and soil conditioner using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of fixing soluble fluorine ions contained in paper sludge incineration ash, to provide a soil conditioner, and further to provide backfill material, mounding material, landfill material or the like using improved sludge. <P>SOLUTION: By causing the paper sludge incineration ash to contact with phosphoric acid, the soluble fluorine ions contained in the paper sludge incineration ash is fixed and, further, by mixing 0.2 to 20 pts.wt. of phosphoric acid to 100 pts.wt. of the paper sludge incineration ash, the soil conditioner capable of absorbing moisture in soil is prepared. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a method for immobilizing soluble fluorine ions contained in paper sludge incineration ash (hereinafter referred to as PS ash) generated by incineration of paper sludge generated in the used paper recycling process, and further to a soil improver It is about.

Because PS ash is porous, it has excellent water retention. For example, by adding to and mixing with sludge discharged during civil engineering excavation, moisture contained in the sludge is adsorbed and the excavated sludge is made dry soil. Consideration has been made.
However, the paper sludge generated during the recycling of used paper also contains fluorine compounds derived from printing ink and calcium compounds such as calcium carbonate as a paper coating agent. Fluorine therein reacts with the calcium compound to change to calcium fluoride and is contained in PS ash. However, since calcium fluoride has a solubility of 0.0016 g / 100 g, if the PS ash is discarded as it is, or mixed with the excavated sludge and discarded, the concentration of dissolved fluorine ions in the elution test announced by the Environment Agency is Can not clear below 0.8mg / L. Therefore, it cannot be disposed of by ordinary landfill.

As a method for immobilizing soluble fluorine ions in PS ash, water is added to PS ash obtained by mixing and incinerating lime refining residue (lime sludge) with paper sludge to immobilize fluorine as calcium fluoride. A method has been proposed (Patent Document 1).
In addition, a method has been proposed in which fluorine is fixed by adding a calcium compound, aluminum sulfates and water to PS ash and mixing them (Patent Document 2).
However, the method of mixing lime generation residue with PS ash to generate calcium fluoride cannot clear the soil standard because of the high solubility of calcium fluoride as described above. Further, the method of adding calcium compounds, aluminum sulfates and water to PS ash of Patent Document 2 also fails to clear the soil standard.

JP 2005-233537 A JP 2005-313147 A

An object of the present invention is to provide a method for immobilizing soluble fluorine ions in PS ash, and to provide a soil improvement material in which 0.2 to 20 parts by weight of phosphoric acid is blended with 100 parts by weight of PS incinerated ash. And

When the present inventors contact PS ash with phosphoric acid, quick lime (CaO) and soluble fluorine ions in PS ash react with phosphoric acid to produce fluorapatite, and the fluorine ions are incorporated into the structure. And the present invention was completed.
That is, according to the present invention, 100 parts by weight of paper sludge incineration ash (PS ash) is subjected to contact treatment with 0.2 to 20 parts by weight of phosphoric acid, thereby fixing soluble fluorine ions in the paper sludge incineration ash. And a soil improvement material containing 100 parts by weight of paper sludge incineration ash and 0.2 to 20 parts by weight of phosphoric acid.

According to the present invention, soluble fluorine ions contained in PS ash can be reduced. That is, according to the present invention, the fluorine ion concentration eluted from PS ash can be reduced to 0.8 mg / L or less of the soil standard in the Environmental Agency Notification No. 46 dissolution test. That is, according to the present invention, phosphoric acid reacts with quick lime and soluble fluoride ions in PS ash to produce fluorapatite and fix soluble fluoride ions in PS ash. Further, when PS ash treated by the method of the present invention is added to sludge discharged during excavation of civil engineering work, moisture contained in the sludge can be adsorbed and sludge can be made into dry soil, backfill material, embankment It can be used for materials and landfills.

Waste paper usually contains calcium hydroxide, calcium carbonate, etc. as coating agents, and simultaneously contains fluorine derived from printing ink. Therefore, in the PS ash obtained by incinerating paper sludge at the time of recycling used paper, the calcium compound is oxidized as quick lime (CaO), and the fluorine reacts with the calcium compound and exists as calcium fluoride. Therefore, when phosphoric acid comes into contact with PS ash, apatite is generated, and at the same time, fluorine apatite that incorporates soluble fluorine ions into the structure is generated, whereby fluorine ions can be immobilized.
In the present invention, the paper sludge incineration ash (PS ash) refers to the ash generated by incineration of paper sludge generated in the used paper recycling process.
Dissolvable fluorine ion concentration in PS ash incinerated paper sludge generated at the time of waste paper generation is usually about 1 to 5 mg / L. By adjusting the amount of phosphoric acid added, higher concentration of soluble fluorine ions Incineration ash containing can also be accommodated.

Examples of phosphoric acid used in the present invention include at least one selected from the group consisting of hypophosphorous acid, phosphorous acid, hypophosphoric acid, metaphosphoric acid, pyrophosphoric acid, orthophosphoric acid, etc., but orthophosphoric acid is inexpensive. And most effective.

In this invention, the addition amount of phosphoric acid is 0.2-20 weight part per 100 weight part of paper sludge incineration ash, Preferably it is 0.5-10 weight part, More preferably, it is 2.0-6.0 weight part is there. The upper limit is not particularly limited, but the addition of 20 parts by weight or more is not economical because the cost increases.

Phosphorus is a eutrophic source for rivers and the like, and is regulated by the drainage standard (less than 16 mg / L). However, in the present invention, the amount of phosphoric acid used is extremely small relative to the CaO content in PS ash. Since all change to apatite, there is no problem with the drainage standards.
In addition, when phosphoric acid is added to PS ash, it may be 100% phosphoric acid or diluted phosphoric acid, but it is appropriately diluted in consideration of miscibility (workability) with PS ash. It is desirable.

The present invention encompasses a soil amendment containing 100 parts by weight PS ash and 0.2-20 parts by weight phosphoric acid. When the soil conditioner of the present invention is added to sludge discharged during excavation in civil engineering work, moisture contained in the sludge can be adsorbed and sludge can be made into dry soil.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.
As the PS ash used as a sample in the following examples and comparative examples, incinerated ash obtained by burning paper sludge generated during recycling of used paper as a fuel for an RPF boiler (RPF: Refuse Paper & Pacific Fuel) was used. The chemical composition of the incinerated ash is shown in Table 1.

また、以下の実施例におけるフッ素およびリンイオン濃度は、それぞれＪＩＳ Ｋ０１０２ ３４．１およびＪＩＳ Ｋ０１０２ ４６．３．３に準じて測定した。
フッ素およびリンイオン以外の濃度は、蛍光Ｘ線分析装置 ＲＩＸ２０００（（株）リガク製）を用いて測定した。測定条件は、ターゲット：Ｒｈ、電圧：５０ｋＶ、電流：５０ｍＡであった。

The fluorine and phosphorus ion concentrations in the following examples were measured according to JIS K0102 34.1 and JIS K0102 463.3, respectively.
Concentrations other than fluorine and phosphorus ions were measured using a fluorescent X-ray analyzer RIX2000 (manufactured by Rigaku Corporation). The measurement conditions were target: Rh, voltage: 50 kV, and current: 50 mA.

In a 200 mL polyethylene container with a stopper, a solution obtained by diluting 15 g of PS ash and 0.6 g of 75% orthophosphoric acid (0.45 g as orthophosphoric acid) manufactured by Rasa Kogyo Co., Ltd. with 4 mL of tap water was mixed well.
150 mL of tap water adjusted to pH 5.8 to 6.3 was added to the obtained PS ash and orthophosphoric acid mixture, and the mixture was shaken continuously for 6 hours using a shaker at normal temperature and pressure. Then, after leaving still for 30 minutes, it processed at 3000 rpm x20 minutes using the centrifuge, and filtered the supernatant liquid with the membrane filter with the hole diameter of 0.45 micrometer, and set it as the test solution. The fluoride ion concentration of the test solution was 0.6 mg / L, which was compatible with the soil standard. Moreover, the phosphorus ion concentration was less than 0.1 mg / L, which was in conformity with the wastewater standard.

In Example 1, it was the same except that 75% orthophosphoric acid was used in an amount of 1 g (0.75 g as orthophosphoric acid). As a result, the fluorine ion concentration in the solution after treatment was 0.4 mg / L, which conformed to the soil standard. Moreover, the phosphorus ion concentration was less than 0.1 mg / L, which was in conformity with the wastewater standard.

(Comparative Example 1)
In Example 1, the same operation was carried out except that a treatment agent (orthophosphoric acid) for immobilizing soluble fluorine ions contained in PS ash was not added. As a result, the fluorine ion concentration in the solution after treatment was 2.3 mg / L, which was incompatible with the soil standard.

(Comparative Example 2)
In Example 2, the same operation was carried out except that the treating agent was changed from orthophosphoric acid to 0.75 g of aluminum sulfate 14-18 hydrate manufactured by Wako Pure Chemical Industries. As a result, the fluorine ion concentration in the treated liquid was 1.5 mg / L, which was incompatible with the soil standard.

(Comparative Example 3)
In Example 2, the same operation was carried out except that the treating agent was changed from orthophosphoric acid to 0.75 g of quick lime manufactured by Hinomaru Mining Co., Ltd. (Hinomaru Lime 20K). As a result, the fluorine ion concentration in the treated liquid was 1.8 mg / L, which was incompatible with the soil standard.

100 g of high pH drilling sludge (water content 65.5%, pH 12.4) is put into a porcelain mortar (diameter 15 cm), and then 10 g of paper sludge incineration ash and 0.67 g of 75% orthophosphoric acid (0.5 g as orthophosphoric acid) ) And mixed with sufficient stirring using a spatula. The obtained high-viscosity slurry was put into a stainless steel vat and air-dried (cured) at room temperature and normal pressure for 1 week.
The air-dried material was passed through a non-metallic sieve having a mesh opening of 2 mm, and they were mixed well to prepare a sample. 15 g of the sample is put into a 200 mL stoppered polyethylene container, 150 mL of tap water adjusted to pH 5.8 to 6.3 is added, and the mixture is shaken continuously for 6 hours using a shaker at normal temperature and pressure. That ’s it. Thereafter, the mixture was allowed to stand for 30 minutes, treated at 3000 rpm for 20 minutes using a centrifuge, and the supernatant was filtered through a membrane filter having a pore size of 0.45 μm to prepare a test solution. The fluoride ion concentration of the test solution was 0.7 mg / L, which conformed to the soil standard.

In Example 6, the same operation was carried out except that the amount of 75% orthophosphoric acid used was 1.33 g (1 g as orthophosphoric acid). As a result, the fluorine ion concentration in the treated liquid was 0.5 mg / L, which was suitable for the soil standard.

(Comparative Example 4)
In Example 6, the same operation was performed except that the treatment agent for immobilizing soluble fluorine ions contained in PS ash was not added. As a result, the fluorine ion concentration in the treated liquid was 1.2 mg / L, which was incompatible with the soil standard.

(Comparative Example 5)
In Example 7, the same operation was carried out except that the treating agent was changed from orthophosphoric acid to 1 g of aluminum sulfate 14-18 hydrate manufactured by Wako Pure Chemical Industries. As a result, the fluorine ion concentration in the treated liquid was 1.1 mg / L, which was incompatible with the soil standard.

(Comparative Example 6)
In Example 7, the same operation was carried out except that the treating agent was changed from orthophosphoric acid to 1 g of quick lime manufactured by Hinomaru Mining Co., Ltd. (Hinomaru lime 20K). As a result, the fluorine ion concentration in the treated liquid was 1.0 mg / L, which was not compliant with the soil standard.

From Examples 1 and 2, by adding orthophosphoric acid to PS ash, soluble fluorine ions contained in PS ash can be adsorbed and immobilized, and the elution fluorine ion concentration of the treated PS ash can be determined by the Environment Agency Notification No. 46. It was also found that it can be adjusted to 0.8 mg / L or less based on soil if measured by the No. elution test.
Further, from Examples 6 and 7, not only by adsorbing and fixing soluble fluorine ions contained in PS ash, but also by mixing with excavation sludge for civil engineering work, PS ash absorbs moisture in the sludge. It turns out that sludge can be made into soil. Furthermore, it turns out that the elution fluorine ion density | concentration in the environmental agency notification 46th elution test of this process sludge can be 0.8 mg / L or less of soil standard.

According to the present invention, since the paper sludge incineration ash can be rendered harmless, the paper sludge incineration ash can be used as a soil improvement material, a backfill material, embankment, landfill, and the like.

Claims (6)

A method for immobilizing soluble fluorine ions in paper sludge incinerated ash, wherein 100 parts by weight of paper sludge incinerated ash is contacted with 0.2 to 20 parts by weight of phosphoric acid. The method according to claim 1, wherein the phosphoric acid is at least one selected from the group consisting of hypophosphorous acid, phosphorous acid, hypophosphoric acid, metaphosphoric acid, pyrophosphoric acid and orthophosphoric acid. The method of claim 1, wherein the phosphoric acid is orthophosphoric acid. The method according to claim 1, wherein the amount of fluorine ions eluted from the contact-treated paper sludge incineration ash is 0.8 mg / L or less in the Environment Agency Notification No. 46 dissolution test. The method according to claim 1, wherein the amount of phosphoric acid is 0.5 to 10 parts by weight per 100 parts by weight of paper sludge incineration ash. A soil conditioner containing 100 parts by weight of paper sludge incineration ash and 0.2 to 20 parts by weight of phosphoric acid.