JP5519307B2 - Method for producing recycled aggregate from incinerated ash containing waste tire ash and the recycled aggregate - Google Patents

Description

  The present invention relates to a recycled aggregate manufactured using incinerated ash of fuel including waste tires, and does not cause a loss of shape when a recycled aggregate molded article is manufactured due to delay in curing.

  In recent years, municipal waste and sewage sludge and other general waste and industrial waste have increased remarkably, and effective use and recycling of waste have been attempted in various fields, but there is no definitive method for waste treatment. The current situation depends on landfill. However, recently, in the cement manufacturing field, eco-cement manufactured using waste such as municipal waste incineration ash as a raw material has been manufactured for the purpose of effective use and recycling of waste (Patent Document 1). In addition, it is made of cement, which is made from aggregate, municipal waste incineration ash, and sewage sludge incineration ash, and is produced by immediate demolding using zero slump concrete by vibration pressure molding machine. (Patent Document 2). On the other hand, pebbles, cement and water were added to the incineration ash burned with a fluidized bed boiler with fuel containing wood chips and RPF as the main components, kneaded, then molded with a vibration pressure molding machine and cured for 1 day. In some cases, it is possible to produce recycled aggregate by paying out to the yard and crushing the molded body.

  The recent increase in oil and coal has led to an increase in the use of inexpensive fuels such as wood chips and RPF, and an increase in the use of waste tires with high calorific value, increasing the proportion of waste tires in the fuel. There is a tendency. The tire contains 4 to 8 wt% of zinc oxide as a vulcanization accelerator, and the incinerated ash obtained by burning the fuel containing the waste tire in the fluidized bed boiler has a high zinc oxide content. Zinc oxide is known as a set retarder for cement and the like (Patent Document 3, Patent Document 4, Patent Document 5). For this reason, if recycled aggregate is produced by the above method using incinerated ash of fuel including waste tires, it will not harden during the curing of the day, so there is a problem that the molded body loses its shape when paid out to the yard. there were.

JP-A-7-165446 Japanese Patent Laid-Open No. 11-263678 JP-A-9-254136 JP-A-2001-314852 Japanese Patent Laid-Open No. 2004-43275

  The present invention provides a high-strength recycled aggregate that is produced using incinerated ash of fuel including waste tires, and that does not lose shape during the production of a recycled aggregate molded product due to delay in curing. The purpose is to do.

  As a result of diligent research to solve the above problems, the present inventors incorporated sodium silicate, sulfate band and / or sodium aluminate when producing recycled aggregate using incinerated ash of fuel including waste tires. Thus, the present inventors have found that a high-strength recycled aggregate that does not lose its shape during production of a recycled aggregate molded article due to delay in curing can be obtained, and the present invention has been completed.

  Fuel incineration ash containing waste tires contains a large amount of zinc oxide, which is a tire vulcanization accelerating aid, and when the recycled aggregate is produced using this incineration ash, the curing of the molded product is delayed. However, since the recycled aggregate of the present invention is manufactured by blending sodium silicate, sulfuric acid band or sodium aluminate with the incineration ash of fuel including waste tires, the mold at the time of manufacturing a recycled aggregate molded product due to delay in curing No collapse occurs. Since the recycled aggregate of the present invention has high strength, it is suitable as a pavement material for sidewalks, roadways and the like.

  According to the present invention, 40 to 100 parts by mass of aggregate, 10 to 40 parts by mass of cement, and 10 to 10 parts of water with respect to 100 parts by mass of incinerated ash obtained by burning fuel containing waste tires with a fluidized bed boiler. 50 parts by weight, sodium silicate, sulfuric acid band and / or sodium aluminate is blended in 1-15 parts by weight, kneaded, vibration pressure molded, cured, and then regenerated aggregate provided Is done.

[Incineration ash]
Incineration ash is the ash left after incineration of fuel. The incinerated ash includes spherical fine particle fly ash blown up with combustion gas and bottom ash that has fallen to the bottom of the incinerator. The incinerated ash used in the present invention is a waste product obtained by burning fuel containing waste tires in a fluidized bed boiler. As a waste tire, you may use the waste tire currently used for the motor vehicle, the bicycle, etc. 1-100 wt% is preferable and, as for content of the waste tire in a fuel, 6-100 wt% is more preferable. Other components of the fuel are coal, wood chips, RPF, paper sludge and the like.

The zinc content in the incinerated ash used in the present invention is 0.2 to 2 wt%, particularly 1 to 1.5%, and the sulfur content is preferably 4 to 8 wt%, particularly 5.5 to 7 wt%. .
[aggregate]
Aggregates are sand, gravel, crushed stone, and similar materials used to make concrete. Aggregates in which 85% or more of the mass remains on the 5 mm screen are called coarse aggregates. Examples of the aggregate used in the present invention include, but are not limited to, natural aggregate, lightweight aggregate, crushed stone, and pebbles. In the present invention, it is preferable to use coarse aggregate, and the particle size is preferably in the range of 2.5 mm to 40 mm. The blending number of the coarse aggregate is preferably 40 to 100 parts by mass with respect to 100 parts by mass of the incinerated ash. When the amount is less than 40 parts by mass, the economic efficiency of the recycled aggregate is deteriorated. When the amount is more than 100 parts by mass, the strength is lowered. The coarse aggregate used in the present invention is preferably pebbles. In the present invention, “to” includes numerical values at both ends thereof.

[cement]
Cement refers to an inorganic adhesive having a property of hardening when kneaded with water. In the present invention, a mixed cement in which inorganic admixtures such as silica fume, silica, fly ash, blast furnace slag and the like are used in addition to normal, early strength, ultra-early strength, moderate heat, sulfate resistance, white and other Portland cement is used. . The cement used in the present invention preferably contains calcium oxide. This is because, as will be described later, calcium hydroxide generated by cement hydration reaction reacts with components derived from sodium silicate and the like used in the present invention to accelerate the hardening reaction in the production of recycled aggregates.

  It is easy to add an admixture such as a water reducing agent or an AE water reducing agent, a thickening agent for enhancing material separation resistance, or the like to the cement used in the present invention. Water reducing agent is an agent that improves the strength of cement and reduces the amount of water required for cement production. AE water reducing agent uniformly disperses fine closed cells in concrete in addition to the function of water reducing agent. It is a drug that has the function of Examples of the AE water reducing agent include lignin sulfonate, polycarboxylate, and oxycarboxylate.

  As for the mixing | blending part number of cement, 10-40 mass parts is preferable with respect to 100 mass parts of incineration ash. If the number of blended parts is less than 10 parts by weight, the strength of the regenerated aggregate decreases, and if it is 40 parts by weight or more, the strength improvement effect is saturated.

[water]
As for the water used by this invention, 10-50 mass parts is preferable with respect to 100 mass parts of incineration ash. When the amount is less than 10 parts by mass, the strength of the vibration-pressed molded body is weak, and the mold collapse occurs immediately after molding. If the amount of water blended is more than 50 parts by mass, the vibration-pressed molded body becomes too soft, so that it loses its shape immediately after molding. Moreover, in order to suppress the elution of harmful components, a chelating agent or sodium sulfide may be added as necessary.

[Sodium silicate, sulfate band, sodium aluminate]
In the present invention, sodium silicate, a sulfate band and / or sodium aluminate is further added to a mixture composed of incinerated ash, aggregate, cement and water. The number of blended parts of sodium silicate, sulfuric acid band and sodium aluminate is 1 to 15 parts by mass, more preferably 4 to 10 parts by mass with respect to 100 parts by mass of incinerated ash. When the blending part number is less than 1 part by mass, the strength improvement effect of the recycled aggregate may not be sufficient. On the other hand, when the blending amount exceeds 15 parts by mass, the hardening of the cement proceeds rapidly, and a recycled aggregate molded body having sufficient strength may not be obtained. Two or more of sodium silicate, sulfuric acid band and sodium aluminate may be used in combination. In this case, the total number of blended parts is preferably 1 to 15 parts by mass and more preferably 4 to 10 parts by mass with respect to 100 parts by mass of incinerated ash.

Sodium silicate refers to a sodium salt of silicic acid and is industrially represented by Na ₂ O.nSiO ₂ .mH ₂ O. n indicates the molecular ratio of SiO ₂ and Na ₂ O, and the properties of sodium silicate differ depending on this value. Sodium silicate becomes solid when n is less than 1, and becomes liquid, i.e., water glass, when n is 1 or more. For this reason, commercially available sodium silicate often displays the content of SiO ₂ . In the present invention, the content of SiO ₂ is not particularly limited, but is preferably 20 to 50 wt%, more preferably 28 to 38 wt%. When the content of SiO ₂ is in this range, sodium silicate becomes water glass.

The sulfate band is aluminum sulfate. In general, commercially available sulfuric acid indicates the alumina content, but in the present invention, the alumina content is not particularly limited.
Sodium aluminate refers to sodium metaaluminate (NaAlO ₂ ) or sodium orthoaluminate (Na ₃ AlO ₃ ).

[Vibration molding]
In the present invention, first, the above-mentioned incineration ash, pebbles, cement, and water are mixed at a predetermined ratio, that is, 40 to 100 parts by mass of aggregate, 10 to 40 parts by mass of cement, and water with respect to 100 parts by mass of incineration ash. 10 to 50 parts by mass, sodium silicate, sulfuric acid band and / or sodium aluminate are blended in 1 to 15 parts by mass, this blend is mixed and kneaded for 1 to 10 minutes, and the resulting paste is put into a mold Then, pressurization and external vibration are sufficient to perform sufficient pressure vibration compaction. For pressurization, a hydraulic or pneumatic pressurizing device or the like can be used. External vibration can be generated using a vibrator or a table vibrator that can be attached to the formwork. Preferable vibration molding conditions are, for example, a frequency of 4500 to 9000 rpm, a vibration acceleration of 10 to 209 g, a pressing force of 0.05 to 1.5 kgf / cm ² , and a vibration pressurization time of 3 to 10 seconds.

[Recycled aggregate molding]
The vibration-molded recycled aggregate molded body can be mass-produced by removing the mold immediately after vibration compaction. The curing method of the molded body removed from the mold is not particularly limited, and may be allowed to cure at room temperature, or may be steam curing or spray curing. After curing for about 1 day, it is dispensed to the yard, and the recycled aggregate molded body is pulverized by a pulverizer to obtain a recycled aggregate having a desired size.

[Recycled aggregate]
The feature of the recycled aggregate of the present invention is that it has high strength, and the recycled aggregate of the present invention has a bending strength of 5 N / mm ² or more (one day, constant temperature curing at 20 ° C.). Therefore, the pavement constructed using the recycled aggregate of the present invention has a relatively large load such as a sidewalk, a playground, and a parking lot that require a relatively small load. It can withstand practical use up to the level of the B traffic division shown in the division.

In the recycled aggregate of the present invention, the zinc content in the recycled aggregate is 0.1 to 2 wt%, particularly 0.7 to 1%, and the sulfur content is 4 to 8 wt%, particularly 5 to 7 wt%. It may be.
[Action]
Although there are many unclear points regarding the hardening accelerating mechanism according to the present invention, the addition of sodium silicate, sodium aluminate, or the like makes it possible to add cement or incinerated ash pozzolan even in the presence of zinc oxide as a setting retarder. This is thought to be because the reaction is accelerated and the hardening of the recycled aggregate molding is promoted. The pozzolanic reaction is a pozzolan composed mainly of silica (SiO ₂ ) and alumina (Al ₂ O ₃ ), which reacts slowly with calcium hydroxide (Ca (OH) ₂ ) derived from cement hydration at room temperature. And a reaction that produces a compound having binding ability. However, the present invention is not limited to this mechanism.

EXAMPLES The present invention will be described in more detail with reference to the following examples. However, the examples are illustrative and do not limit the scope of the present invention.
[Example 1]
Waste incineration ash fly ash (FA) 83 parts by mass and bottom ash (BA) 17 67 parts by mass of pebbles (bills), 25 parts by mass of cement, 8.3 parts by mass of sodium silicate (SiO ₂ content: 38 wt% product), 33 parts by mass of water, After kneading for 210 seconds in a product name: Zykurosu, manufactured by Kitagawa Steel Co., Ltd.), a regenerated aggregate molded product of about 30 cm square is prepared using a vibration press molding machine (model: CF type, manufactured by Chiyoda Machinery Co., Ltd.). Individually produced. The molding conditions were as follows: press vibrator frequency 87 Hz, press vibrator excitation force 4790 kg, table vibrator frequency 99 Hz, table frequency excitation force 8780 kg, press pressure 0.55 kgf / cm ² , press time 5.3 seconds. there were. The regenerated aggregate molded body was cured at 30 ° C. for 24 hours, and conveyed to a belt conveyor to evaluate the degree of occurrence of deformation when dropped to a yard from a height of 1.5 m. Moreover, the uniaxial compressive strength (according to JIS A8401) after 24-hour curing was also measured.
[Example 2]
A recycled aggregate molded body was produced and evaluated in the same manner as in Example 1 except that the blending number of sodium silicate in Example 1 was changed from 8.3 parts by mass to 4.2 parts by mass.
[Example 3]
A recycled aggregate molded body was produced and evaluated in the same manner as in Example 1 except that the sodium silicate of Example 1 was changed to a sulfuric acid band (alumina content: 8 wt% product).
[Example 4]
A recycled aggregate molded article was produced and evaluated in the same manner as in Example 3 except that the number of parts of the sulfuric acid band in Example 3 was changed from 8.3 parts by mass to 4.2 parts by mass.
[Example 5]
A recycled aggregate molded body was produced and evaluated in the same manner as in Example 2 except that sodium silicate in Example 2 was changed to sodium aluminate (solid).
[Comparative Example 1]
In the same manner as in Example 1 except that the mixing ratio of the waste tire of Example 1 was changed from 20 wt% to 5 wt%, the mixing ratio of wood chips was changed from 55 wt% to 70 wt%, and no sodium silicate was further added. A recycled aggregate molded body was manufactured and evaluated.
[Comparative Example 2]
A recycled aggregate molded body was produced and evaluated in the same manner as in Example 1 except that the sodium silicate of Example 1 was not blended.
[Comparative Example 3]
A recycled aggregate molded body was produced and evaluated in the same manner as in Example 1 except that the number of blended parts of the cement of Example 1 was changed from 25 parts by mass to 50 parts by mass.
[Comparative Example 4]
A recycled aggregate molded body was produced and evaluated in the same manner as in Example 1 except that sodium silicate in Example 1 was changed to quick lime (solid).

  The results are shown in Table 1. From the results of Examples and Comparative Examples, it is clear that the recycled aggregate of the present invention is excellent in strength. It is also clear that recycled aggregates with excellent strength can be obtained even when incinerated ash with an increased waste tire content is used.

  Table 2 shows the results of fluorescent X-ray analysis of the incinerated ash used in Comparative Examples 1 and 2 and the recycled aggregate produced using the incinerated ash. The zinc concentration in the regenerated aggregate obtained in Comparative Examples 1 and 2 is about 0.2 and about 0.9 wt%, and the sulfur concentration is about 5.4 and about 5.1 wt%. These recycled aggregates are recycled aggregates obtained using incinerated ash obtained by incineration of fuel with a waste tire content of 20 wt% without using sodium silicate or the like, and are shown in Table 1. As shown in the figure, the shape is lost at the time of payout after 24 hours.

  On the other hand, as shown in Table 1, the recycled aggregates produced using incinerated ash obtained by incinerating fuel with a waste tire content of 20 wt%, sodium silicate, etc., after 24 hours No out of shape when paying out. Since the addition amount of sodium silicate and the like is about 1 to 15 parts by mass with respect to 100 parts by mass of incinerated ash, the zinc concentration and sulfur concentration in the recycled aggregate produced in the example were obtained in Comparative Example 2. It is considered that the concentration in the recycled aggregate is almost the same. That is, according to the present invention, it is clear that a regenerated aggregate having excellent strength can be obtained even if the zinc concentration in the regenerated aggregate is about 0.9 wt% and the sulfur concentration is about 5.1 wt%. is there.

Claims (5)

With respect to 100 parts by mass of incinerated ash obtained by burning a fuel containing waste tire and containing 6 to 100 wt % of the waste tire in a fluidized bed boiler,
After mixing and kneading 40-100 parts by weight of aggregate, 10-40 parts by weight of cement, 10-50 parts by weight of water, 1-15 parts by weight of sodium silicate, sulfate band and / or sodium aluminate,
After vibration pressure molding and curing,
Obtained by crushing, bone material. The content of zinc in ash is 0.2~2wt%, the content of sulfur is 4~8wt%, claim 1 aggregate according. (1) A step of preparing incinerated ash by burning fuel including waste tires in a fluidized bed boiler;
(2) For 100 parts by mass of the incineration ash,
40-100 parts by mass of aggregate,
10 to 40 parts by mass of cement,
10 to 50 parts by mass of water, and 1 to 15 parts by mass of sodium silicate, sulfuric acid band and / or sodium aluminate, and kneading to obtain a mixture,
(3) After the mixture was vibrating pressure molding, curing to, obtaining a molded body, and (4) a step of crushing the molded bodies, including method of the aggregate. The manufacturing method of Claim 3 whose content of the waste tire in the said fuel is 6-100 wt%. The production method according to claim 3 , wherein a content of zinc in the incineration ash is 0.2 to 2 wt% and a content of sulfur is 4 to 8 wt%.