JP2006326462A - Method for recycling ash as cement raw material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for simply and efficiently removing chlorine included in an incineration residue dug out from final disposal facilities in which the incineration ash, incineration fly ash, molten fly ash and dust incineration residue and the like are embedded, which technique removes water soluble chlorine as well as sparingly soluble chlorine and avoids hindrance to recycling of the residue as cement raw material. <P>SOLUTION: In recycling as the cement raw material by removing chlorine included in the dust incineration residue dug out from the final disposal facilities in which the incineration ash, incineration flying ash, dust incineration residue and the like are embedded, the method for recycling ash as cement raw material is characterized by using an aqueous solution containing a carbonate as cleaned water. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention includes incineration ash generated during incineration of general waste and industrial waste, incineration fly ash and molten fly ash, and waste incineration residue excavated from the final disposal site where waste incineration residue is buried. This technology is related to the technology to remove the chlorine and recycle as cement raw material.

  Most of the incineration residue such as incineration ash and incineration fly ash generated during the incineration of general waste and industrial waste is landfilled at the final disposal site. However, in recent years, it has become difficult to secure a final disposal site, and the effective use of these ashes has become a major issue.

  On the other hand, in addition to the above-mentioned incineration residue, a wide variety of wastes such as plastics, bottles, cans, and debris are randomly buried in conventional final disposal sites. Many of these landfills can be recycled if they are separated. Recyclable waste is extracted from the final disposal site that is full or the final disposal site currently in use. Recycling without causing environmental impacts can effectively use resources and prolong the life of final disposal sites. Therefore, development of intermediate treatment technology for the effective use of these ashes is desired.

  As an effective utilization method of ash, there are heavy metal recovery called cement raw material or Yamamoto reduction. Regarding the use of waste as a raw material for cement, JIS Eco-JIS was established (JIS R5214), and it is expected that waste will be used more effectively in cement production, especially eco-cement production. However, a large amount of chlorine remains in incineration ash, fly ash, and sorted incombustibles. If these incineration residues are used as they are for cement production, the input amount is considerably limited. Therefore, dechlorination is essential, and an efficient chlorine removal technique is required.

Since these chlorines are mainly water-soluble, washing with water is generally performed for dechlorination, and a technique for eluting the chlorine content in waste into water is known. For example, a technique has been proposed in which incineration ash is washed with water to remove chlorine and then used as a cement raw material (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 9-187748

  However, simply washing the incineration residue with water dissolves only a portion of the contained chlorine, and there are poorly water-soluble salts such as Friedel's salt in the chlorine content. It cannot be treated with water washing alone. In particular, the chlorine content in the waste incineration residue at the final disposal site where the waste incineration residue is buried is washed away with water-soluble chlorine by rainwater, and as a result, the proportion of poorly water-soluble chlorine is high. Also have problems such as low dechlorination effect.

  An object of the present invention is to provide a simple and efficient chlorine removal technique in which not only water-soluble chlorine but also poorly soluble chlorine is sufficiently removed, and there is no hindrance to ash as a cement raw material. .

  As a result of diligent studies to solve the above problems, the present inventors have used incinerated ash, incinerated fly ash, and sorted incombustible materials rather than simple water washing by using an aqueous solution in which carbonate is added to washing water. The present inventors have found that the chlorine content can be reduced and have reached the present invention.

  That is, the present invention relates to washing water for at least one ash selected from the group consisting of incineration ash, incineration fly ash, molten fly ash, and waste incineration residue excavated from a final disposal site where waste incineration residue is embedded. In the method of adding chlorine and removing chlorine contained in the ash to obtain a cement raw material, the gist of the method for converting the ash into a cement raw material, using an aqueous solution containing carbonate as washing water It is.

  According to the present invention, the chlorine-containing concentration in the ash obtained by washing with an aqueous solution to which carbonate has been added can be effectively removed. In other words, chlorine in the incineration residue excavated from the final disposal site where incineration ash, incineration fly ash, molten fly ash and waste incineration residue are buried can be effectively separated and obtained after solid-liquid separation. It becomes possible to recycle the washed residue as a raw material for cement.

  Hereinafter, the present invention will be described in detail.

  In the present invention, the ash to be used as a raw material for cement is incineration ash, incineration fly ash, molten fly ash, or waste incineration residue excavated from a final disposal site where waste incineration residue is buried. Incineration ash refers to ash produced when incineration of general waste and industrial waste in an incinerator. Incineration fly ash refers to the treatment of acid gas generated during incineration of general waste and industrial waste. The generated ash is referred to as molten fly ash. The molten fly ash refers to the ash produced when the incinerated ash or the acid gas generated when the incinerated fly ash is melted is treated.

  In addition, the waste incineration residue excavated from the final disposal site where waste incineration residue etc. is buried is roughly 100 mm of coarse and magnetic sorting of the excavated waste generated when the final disposal site is excavated, After drying the portion of 100mm or less from which iron has been removed, perform vibration sieving and manual sorting, and finally sort it into earth and sand, combustibles + plastics, bottles / cans, stones / rubbles, including incineration residue It is one of those obtained.

  In the present invention, one or more selected from these may be used, and a mixture of a plurality of ashes may be used.

  In the present invention, washing water is added to and mixed with the ash to elute chlorine contained in the ash into the washing water, and an aqueous solution containing carbonate is used as the washing water.

  Examples of the carbonate used in the present invention include ammonium carbonate, potassium carbonate, potassium carbonate sodium, sodium carbonate, lithium carbonate, ammonium hydrogen carbonate, potassium hydrogen carbonate, and sodium hydrogen carbonate. Among these, sodium carbonate is preferable from the viewpoint of reaction equivalent and cost.

  The addition amount of the carbonate is preferably added to the aqueous solution so as to be 0.1 to 10 parts by mass, particularly 1 to 5 parts by mass with respect to 100 parts by mass of the cleaning object. If the addition amount is less than 0.1 parts by mass, the effect of removing chlorine is insufficient, and if it exceeds 10 parts by mass, the chemical cost of carbonate increases, which is not preferable.

  It is known that carbonate ions have the effect of decomposing and solubilizing poorly soluble chlorine such as Friedel's salt. In the present invention, using this principle, it is considered that the chlorine component that could not be eluted by water washing alone can be further eluted to the washing water side.

  In the present invention, the amount of washing water containing carbonate is preferably such that the solid-liquid ratio between the washing object and the washing water is the wet weight of the washing object: the capacity of the washing water = 1: 1 to 1:30. Particularly preferred is 1: 2 to 1:10. If it is less than 1: 1, mixing and chlorine dissolution become difficult, and if it exceeds 1:30, the equipment capacity and the wastewater treatment burden increase, which is not preferable.

  In the present invention, the pH of the incombustible material becomes about 10 to 11 by adding the washing water containing carbonate as described above.

  In the mixing method of the present invention, after washing water is added, washing operation is performed using immersion washing or mechanical stirring. When using mechanical stirring, any means may be used, for example, stirring may be performed for 10 minutes to 2 hours using a rotary stirrer. Also, means for promoting physical cleaning such as ultrasonic cleaning and grinding cleaning may be used.

  In the present invention, the temperature of the washing water is preferably set to 30 to 100 ° C., more preferably 40 to 80 ° C., in order to increase the chlorine removal effect. As an operation, the temperature may be adjusted using a constant temperature water bath so that the washing water has a predetermined liquid temperature.

  In the present invention, after addition and mixing of the washing water, dehydration is then performed to separate the washing filtrate and the washing residue. Any method may be used as a means for dewatering, for example, gravity sedimentation separation, centrifugation, belt press, or the like is used.

  In the present invention, in order to increase the chlorine removal effect, multi-stage cleaning may be used. For example, first cleaning by immersion cleaning or other methods is performed first, and the water washing residue obtained after solid-liquid separation is immersed. You may perform washing | cleaning or the 2nd washing | cleaning by the other method, and may perform dehydration after that.

  For the washing filtrate generated after washing, trace heavy metals are removed by existing wastewater treatment, and then neutralized and discharged to the outside of the system, or salt recovery is performed by concentrated crystallization, etc. May be.

  The cleaning residue from which chlorine has been removed according to the present invention is adjusted by adjusting the amount of water and the particle size by drying and pulverization, and is then transported and used as a cement raw material. The lower the chlorine concentration after the cleaning treatment, the better. However, it is preferable that the chlorine content of the JIS standard cement raw material is 350 ppm or less as much as possible. As the chlorine concentration decreases, the rate at which the material obtained by this cleaning process is replaced with a portion of the cement raw material increases.

  Hereinafter, the present invention will be specifically described by way of examples.

  In this example, the chlorine content was measured by a shaking extraction method and an alkali melting method.

  In the shake extraction method, 100 parts by weight of water is added to 1 part by weight of the sample and shake extraction is performed. The extract is measured by the mercury (II) thiocyanate absorptiometry, and the obtained value is used as the chlorine content. did.

  In the alkali melting method, a predetermined amount of potassium sodium carbonate was added to a sample and the mixture was alkali-melted at 900 ° C., the melt was measured by mercury (II) thiocyanate absorptiometry, and the obtained value was used as the amount of chlorine.

  The two types of chlorine content measurements are defined as the poorly water-soluble chlorine content defined as the difference between the chlorine content by the alkali melting method and the chlorine content by the shaking extraction method, and the poorly water-soluble chlorine concentration by washing described below The purpose is to know the removal effect.

Example 1
Distilled waste generated by excavating the final disposal site, including chlorine incineration residue (1) with chlorine content of 5,060mg / kg-dry (shaking extraction method) and 5,200mg / kg-dry (alkaline melting method) 120 mL of aqueous solution (solid-liquid ratio 1: 3) in which 0.4 g of sodium carbonate was added to 40.0 g (wet amount) of the incineration residue obtained by screening the was added as washing water, and the mixture was stirred with a small stirrer at 120 rpm for 1 hour. After stirring, solid-liquid separation was performed, and the water content was 26.2 g (dry weight) as a residue of water (1) with a chlorine content of 745 mg / kg-dry (shaking extraction method) and 1,245 mg / kg-dry (alkali melting method). 101 mL of water washing filtrate (1) having a chlorine-containing concentration of 824 mg / L was obtained.

Example 2
120 mL of an aqueous solution in which 2.0 g of sodium carbonate was added to 40.0 g (wet amount) of the same sorted incineration residue (1) as in Example 1 (solid-liquid ratio 1: 3) was added as washing water, and output by an ultrasonic cell crusher 20 The temperature at the time of mixing and washing was adjusted to 80 ° C. by using Watt, stirring with a small stirrer 120 rpm, and a constant temperature water bath, and ultrasonic wave + stirring + high temperature water washing was performed for 1 hour. After the stirring, solid-liquid separation is performed, and the water content is 28.6g (dry weight) as a residue (2) with chlorine content of 675mg / kg-dry (shaking extraction method) and 1,100mg / kg-dry (alkali melting method). 88.5 mL was obtained as a water-washed filtrate (2) having a chlorine-containing concentration of 953 mg / L.

Comparative Example 1
120 mL of water (solid-liquid ratio 1: 3) is added to 40.0 g (wet amount) of the same incineration residue (1) as in Example 1, and stirring is performed at 120 rpm for 1 hour with a small stirrer without adding sodium carbonate. After stirring, solid-liquid separation is performed, and 25.4 g (dry weight) of water-washing residue (3) with a chlorine-containing concentration of 1,040 mg / kg-dry (shaking extraction method) and 1,605 mg / kg-dry (alkali melting method) And 102 mL was obtained as a water-washing filtrate (3) whose chlorine content concentration is 768 mg / L.

Comparative Example 2
120 mL of water (solid-liquid ratio 1: 3) was added to 40.0 g of the same incineration residue (1) as in Example 2, and the output was 20 watts with an ultrasonic cell crusher without adding sodium carbonate, and stirring with a small stirrer was 120 rpm. And the temperature at the time of mixed washing was adjusted to 80 ° C. using a constant temperature water bath, and ultrasonic wave + stirring + high temperature water washing was performed for 1 hour. After stirring, solid-liquid separation was performed, and the water content was 27.4g (dry weight) as a residue (4) with a chlorine content of 950mg / kg-dry (shaking extraction method) and 1,465mg / kg-dry (alkali melting method). 90.8 mL was obtained as a water-washed filtrate (4) having a chlorine-containing concentration of 872 mg / L.

  Chlorine content and Example 1, 2 and comparison for water washing residue (1), (2) obtained in Examples 1, 2 and water washing residue (3), (4) obtained in Comparative Examples 1, 2 It shows in Table 1 about the chlorine containing density | concentration in the water washing filtrate in Example 1,2.

From Table 1, the chlorine content concentration in the washing residue in Comparative Example 1 is 1,040 mg / kg-dry (shaking extraction method), 1,605 mg / kg-dry (alkaline melting method), and the chlorine content concentration in the water washing filtrate is 768 mg. On the other hand, the chlorine concentration in the washing residue obtained in Example 1 is 745 mg / kg-dry (shaking extraction method), 1,245 mg / kg-dty (alkaline melting method), and in the washing filtrate. The chlorine concentration of 824mg / L is 824mg / L, and it can be seen that chlorine removal is effectively performed by adding carbonate and washing. Moreover, by adding ultrasonic cleaning and high-temperature water cleaning as in Example 2, the chlorine content concentration in the water washing residue is 675 mg / kg-dry (shaking extraction method), 1,100 mg / kg-dty (alkali melting method) ), The chlorine content in the water wash filtrate is 953 mg / L, indicating that the chlorine removal effect is improved.

  About the difference of the chlorine concentration analysis result in the washing residue in the shaking extraction method and the alkali melting method, it is 565 to 875 mg / kg-dry in Comparative Examples 1 and 2, whereas in Examples 1 and 2, it is 425 to 500 mg / kg. It is kg-dry, and it can be seen that the removal of poorly water-soluble chlorine is also effectively carried out.

  From the above, it can be seen that not only water-soluble chlorine but also poorly water-soluble chlorine can be removed by washing with an aqueous solution to which carbonate is added as washing water. As a result, the chlorine content concentration of the obtained cement raw material can be further reduced. Therefore, it becomes possible to replace the substance obtained by this cleaning treatment with a part of a normal cement raw material at a larger ratio.

Claims (1)

Wash water is added to at least one ash selected from the group consisting of incineration ash, incineration fly ash, molten fly ash, and waste incineration residue excavated from the final disposal site where waste incineration residue is buried, and the ash A method for converting ash into a cement raw material, wherein an aqueous solution containing carbonate is used as cleaning water in a method of removing chlorine contained in a shell to obtain a cement raw material.