JPS59164667A - Manufacture of crystallized aggregate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial use of aggregate) The present invention relates to a method for producing crystallized aggregate using waste incineration ash such as sewage sludge incineration ash and municipal solid waste incineration ash as a raw material.

(Prior art) Conventionally, sewage sludge and garbage generated from sewage treatment plants and garbage treatment plants in various places have been incinerated and disposed of as incinerated ash in landfills, since dumping them directly in landfills poses hygiene and odor pollution problems. However, it is becoming difficult to secure land for landfills, and secondary pollution associated with landfill disposal, such as the elution of heavy metals from incinerated ash, has become a major social problem. The effective use of waste incineration ash by melting it is being considered. As an attempt to melt and mold waste incineration ash and use it effectively as aggregate, etc., as shown in Special Publication No. 010 of Sho Syo-2G, the molten material was dropped into a water-sealed box. There is a method of obtaining aggregate in the form of small glass tubes by solidifying it in water, but the glass aggregate obtained by this method has the problems of low strength and lack of chemical stability. In addition, the method of obtaining aggregate by inserting a melt into a spinning mold and solidifying it to obtain large chunks of crystallized material and then crushing it requires a large-scale crushing device to produce aggregate. This method has problems such as requiring a large amount of crushing cost.

(Objective of the Invention) The present invention solves the above-mentioned problems and facilitates the mass production of high-strength crystallized aggregates that have excellent mechanical strength and chemical stability, and have a particle size distribution that matches the intended use. It was completed with the aim of producing a crystallized aggregate that can

(Structure of the Invention) The main composition of the present invention is 8102.2j;~lS% (weight%, the same hereinafter), A71203j~/j%,
Fe2O3! ;-,2! ;%, Ca0.2o-a
o%, MgO/~/j%, P2O5/~10% (OaO+MgO)/8i02.

Waste incineration ash 133 whose composition has been adjusted to a ratio of 08 to 7.2
0~/! It is characterized in that it is melted at 00''C, the melt is rapidly cooled and subjected to thermal shock crushing, and then held at 1000 to 1rooC for 30 minutes or more to crystallize.

The waste incineration ash used as a raw material in the present invention is sewage sludge incineration ash or municipal waste incineration ash, and these waste incineration ash contain S Io2, Al2O3, Fe2O3,
Besides CaO%MgO, P2O5, Na2O'
4 is mainly included, and their content varies slightly depending on the type of incineration ash. Looking at the melting characteristics of waste incineration ash, that is, the relationship between viscosity and melting humidity, the forming temperature range corresponding to the viscosity range suitable for forming ordinary glass is extremely narrow compared to ordinary glass. It has the property of "short-legged glass", and also, for example / 3
! ; Since the viscosity 19 in the melting temperature range of 0'C or higher is considerably lower than that of ordinary glass, it is suitable to allow Fr to flow down naturally from the bottom of the melting furnace after melting, but such a composition should not be disposed of. In order to melt, weld, crush and crystallize incineration ash into aggregate, SiO2,2! ; ”'-'I
0%-preferably 30-110%, AJ203j~/
S% preferably Fi5~IO%, 1°'e203! ;-,
25% good t L< ha, s ~/j%, CaO, 20 ~
Q □% preferably 30-3! %, MgO/-j% preferably 2-j%, P2O5/-10% preferably 2-j%
Within the range of 10% and (OaO+MgO) / Si
02 Jt F0. II ~/, 2 Good! i! L
<ld O, 9~/.

/Is it important to be within the range of /, for this reason than an incinerator? The collected waste incineration ash is analyzed, and if the composition range is not within the specific composition range, it is adjusted to fall within the composition range mentioned above.In addition, when adjusting the composition, inexpensive clay, shirasu, red iron ash is used. , coal, dolomite, bone ash, etc. are preferably used. The waste incineration ash whose composition has been adjusted in this way is 13so-iso in a melting furnace.
The molten material is melted at a diameter of about 1.0"C, and while maintaining the viscosity at a required viscosity of, for example, 1O1 poise or less, preferably 10% Boise or less, it is passed through the melting furnace sprue to a diameter corresponding to the final aggregate particle size, for example, I. The melt is allowed to flow down to form a rod-shaped or string-like falling melt with a diameter of about 3 to /Q mm, and the falling melt is cooled by spraying water or sprayed with cooling gas to perform thermal shock crushing. Subsequently, the crushed material is heated to 100-1, 200°C, preferably 1os, in a crystallization furnace using, for example, the melting furnace exhaust gas as a heat source.
The crushed material is heated and maintained at a predetermined temperature within the temperature range of 0 to 30° C. for 30 minutes or more, preferably 30 minutes or more, to cause formation of crystal nuclei in the crushed material and crystal growth centered on the crystal nuclei. Since the granular crystallized material obtained in this way has already been crushed by thermal shock crushing in the previous step, it can be made into a product as it is or after being classified, so that it can be made into a product with a particle size larger than the desired size. In some cases, it is possible to produce products within specifications by classifying them in a heated state and subjecting only those with a diameter larger than the specified size to millimeter thermal shock crushing, which simplifies the series of manufacturing steps. In addition, in the present invention, if 5t02 is set to 2J--15%, Fi, j is less than 5%, 8i02 as a glass-forming skeleton is insufficient and a high-strength crystallized product cannot be obtained. This is because the viscosity increases at the melting temperature, which makes it difficult for the melt to naturally flow down from the bottom of the furnace, and also has a negative effect on crystallization. ~/
The reason why #, '203 is less than 5% is because a high-strength crystallized product cannot be obtained, and when it exceeds 75%, the melting temperature becomes too high. 2
．． ! It is an important component not only as a fluxing agent but also as a nucleating agent, and its amount is 5%.
If it is less than 1.2S%, the effect as a fluxing agent is weak and the melting temperature is not lowered, and the formation of crystal nuclei is insufficient.If it exceeds 1.2S%, the strength is significantly reduced.
The reason for setting O to 20 to % is because if 01LO is less than 20%, the viscosity of the melt will increase, it will have a negative effect on crystallization, and the strength will decrease, and if it exceeds 110%, the chemical stability will decrease significantly. In addition, 7 to 5% Ume O
This is because although MgO is used as a composition adjusting agent in place of CaO and has the effect of increasing chemical stability, it has no effect if the content is less than 7%, and if the content exceeds 5%. This is because the effect does not change even if P2O5
The reason why P2O5 is set at 7 to 10% is because P2O5 is the most important component as a nucleating agent, and if its amount is less than 1%, the
In the temperature range of 1200℃, no crystal nuclei are formed and 70%
Exceeding this is not preferable as it causes a decrease in strength. Furthermore,
(OaO ten MgO) / 8 '02 ratio θg~/,,
2 is important not only for lowering the melting temperature but also for crystallizing the melt.If this mixing ratio is less than 0g or exceeds f2, the melting temperature will increase by 1. This is undesirable because it corrodes the furnace material of the melting furnace and increases melting costs. Next, the melting temperature of waste incineration ash is set to 1350~
/! ;00℃ is limited to m within the above composition range! Since the molten material of regulated waste incineration ash has the property of so-called "short-legged glass" in which the viscosity decreases rapidly as the melting temperature rises, it is difficult to melt from the melting furnace sprue at temperatures below /33; 0'C. The viscosity required for the melt to flow down is preferably 10 poise or less. Since the viscosity of 10 poise or less cannot be obtained, the diameter of the melt flowing down becomes large and thermal shock crushing cannot be performed sufficiently.
This is because it is necessary to crush it again in the subsequent process, and
iso in actual plants.

Maintaining a melting temperature exceeding °C involves a large loss in terms of equipment and energy costs, so the upper limit is set at 1so.
o″C, and further, in the crystallization process after crushing, 1o
oo~/, heat treatment at a temperature of 200'C"1
Melt r・1j temperature /3! ;0~/! ; This is because it is best to maintain the temperature in the 00° C. range from the point of view of effective use of thermal energy. In addition, the crystallization temperature is 10OQ~/20
The reason why we limited it to 0℃ is because the composition is consistent with the above composition. This is because crystal growth of the -1 waste incineration ash is difficult to occur sufficiently at temperatures below 100°C, and stable crystal growth is hindered by remelting of crystallized substances when the temperature exceeds 7200°C. In addition, during crystallization, it is more preferable to maintain the temperature at a constant temperature within a specific temperature range for a predetermined period of time in order to form uniform crystal nuclei and grow crystals. Almost the same results were obtained even if the temperature was slowly lowered or increased over a period of time.Also, the crystallization time was set to 30 minutes or more because complete crystallization cannot be achieved with a holding time of less than 30 minutes. This is because high-strength crystallized aggregate cannot be obtained. The crystallized aggregate obtained in this way not only has high strength, but also has a predetermined particle size distribution adjusted from the beginning as the final aggregate used, so post-processing such as crushing, cutting, and processing is required. This eliminates the need for time and effort.

(Effects of the Invention) As is clear from the above description, the present invention melts waste incineration ash with a specific composition range under specific melting conditions, rapidly cools it, thermally crushes it, converts it into a skeletal shape, Crystallized aggregate with excellent mechanical strength and chemical stability can be easily obtained by processing under certain conditions, and crystallized aggregate with such excellent properties can be mixed with cement. It has a very wide range of uses, including ordinary aggregate used as aggregate, crushed stone used for road backfilling, etc., and melting furnace exhaust gas can also be effectively used for crystallization. Since this process is carried out by thermal shock crushing by rapid cooling of the molten material, the cost can be reduced by 20 to 30% compared to mechanical crushing after molding, and it is also superior in terms of energy savings. Crystallization using waste incinerated ash as a raw material has various advantages such as eliminating the need for landfill sites and secondary pollution for waste incinerated ash, and solves the problems of conventional waste incinerated ash processing. This is an extremely important method for producing bone tissue that contributes to the development of the industry.

(Example) Is the chemical composition and composition ratio of waste incineration ash from various sewage treatment plants as shown in the table below? J, 1 and melted in a time S in a melting furnace maintained at a temperature within /380-/1IIfO°c according to their respective melting characteristics, while maintaining the viscosity of the melt below lO Boyce. It is allowed to flow down from the sprue of the melting furnace in a rod shape of 55-5yφ, and the falling melt is sprayed with 3~j'/nil of spray water to be rapidly cooled and crushed by heat, and then the crushed material is crushed by 10j.
Table 1 shows the crystallized aggregate A/~A// obtained by crystallizing it in a crystallization furnace maintained at O~1iso"c for 0 minutes and classifying it into a predetermined particle size. As a reference example, aggregate boiled 12~A/l obtained under the composition and heat treatment conditions outside the numerically limited range of the present invention described as the present invention example and L7. Table 1 shows the results of a concrete strength test conducted using the crystallized aggregate according to the JI8 standard in comparison with aggregates outside the numerical limits of the present invention and river sand. As shown in Table 1, it was confirmed that the crystallized aggregate obtained by the present invention has superior mechanical strength and chemical stability compared to the aggregate obtained by the reference example.

Claims (1)

[Claims] The main composition is 8102. zs-1Is% (1 back, same below), Al203j ~/5%, Fe2O3j;
~,! 3%, Oao, 20~IIO%, Mgo/-/!
i%, P2O5/-/ Q% (7) Within range f Kak(
OaO+MgO) / 8! 02(2) ratio o,
g~/・2 waste incineration ash /3! ;0~
/! Melting WA at 00'C with melting 17! After rapidly cooling the material and subjecting it to thermal shock crushing, it was heated to 1000-/200'C for 3
1. A method for producing crystallized aggregate, characterized in that it is crystallized by holding it for 0 minutes or more.