JPS5830380A - Treatment for incineration ash of sewage sludge - Google Patents

Abstract

PURPOSE:To obtain aggregate which is light in weight and is highly strong by adding dehydrated cake of sewage sludge to incineration ashes of sewage sludge. CONSTITUTION:In controlling the moisture content of the incineration ashes of sewage sludge by adding dehydrated cake of the same sewage sludge to said ashes and calcining the same after granulating the sludge, the dehydrated cake is added at 10-80pts.wt. by dry solid weight to 100pts.wt. the incineration ashes of the sewage sludge. The sludge contg. <=15% calcium oxide is used. A rotary kiln or the like is used for granulation and the sludge is granulated to 0.5-15mm. grain sizes.

Description

[Detailed Description of the Invention] The sewage sludge 1 incineration ash is granulated and then calcined to produce light ashes.

In order to reduce sewage treatment p1j: sludge Cj, and its disposal IT), it is often dehydrated and disposed of as incinerated ash, but the - m' is so large that it is difficult to secure a landfill site by φ1r. Therefore, there is a strong desire to develop a method for effectively utilizing this sewage sludge incineration ash.

In order to meet this demand, the present invention has conducted various studies in an attempt to produce a lightweight aggregate with a light weight of 1↑1 and 100% dust by granulating and burning sewage sludge incineration ash.

According to the results, when sewage sludge incineration ash is granulated by adding dehydrated sewage sludge cake, a strong granulated product can be obtained when the amount of sewage sludge water cake added is within a specific range. It has been found that by firing the granules obtained in (1) above, sintered granules with low specific gravity and high strength can be obtained at a relatively low firing temperature.

Next, the experimental results will be explained.

The composition of the incineration ash used in the experiment was as shown in Table 1 in weight percent, and the dehydrated cake of sewage sludge added to the trench incineration ash was obtained from the same sewage treatment plant.

Table 1 (%) Dehydrated cake was added to the incineration ash in various proportions and granulated, and the relationship between the amount of dehydrated cake added and the crushing strength of the granulated product was determined, and the results shown in Figure 1 were obtained. . Next, the relationship between the addition of the dehydrated cake to this granulated material, the I3% composition, and the specific gravity of the baked product was determined, and the results shown in Figure 2 were obtained.

From Figure 1, it was found that as the amount of dehydrated cake added to the incinerated ash was increased, the pressure α1 strength of the granules increased. However, in reality, there is a limit to the dripping moisture meter used during granulation, so the moisture content of the dehydrated cake (〒1 automatically limits the addition of F; 1゛ to -1゛). .

Next, as shown in Figure 2, it was found that by increasing the amount of dehydrated cake added to the incinerated ash, sintered granules with low specific gravity could be produced at relatively low temperatures.

The fracture strength of the sintered granules of Katsuda and Gorera by the BS-812 method was 36 to 419.

Here, Utomomagi crushing strength is a type of method for measuring the toughness of granules. This is a test method to see if it will break under a load of 41 degrees.

The Shoda BS-812 method is based on the British standard, in which samples are placed in a cylinder with a bottom to a certain degree of uniform particle size, then a predetermined load is applied to the crushed material, and the crushed material is crushed to a predetermined f! This is a method that divides by Ri and indicates the amount under the sieve in %.

The present invention is based on these findings, and is characterized by adding a dehydrated cake of the same sewage sludge to the incineration ash of the sewage sludge, adjusting the moisture content, granulating it, and then firing it. This is a method for processing sludge incineration ash.

In the present invention, when slaked lime is added in the process of agglomerating sludge from sewage, sedimentation, and dehydration, the content of oxidizing lime in the sludge increases, so it is difficult to melt when the granules are fired at high temperatures. It is desirable to use sludge with an amount of calcium oxide of 15% or less, since this makes it easier for the calcium oxide to adhere to the sludge.

The amount of sludge dehydrated cake added to sewage sludge incineration ash cannot be determined unconditionally as it varies depending on the water content of the dehydrated cake, but it is
1 part of dehydrated cake as its dry solid content
It is preferable to adjust the water content of the mixture and granulate it.

Granulation in the present invention is carried out by adding a suitable dehydrated cake to the incineration ash, kneading it, and then using a conventional 1111 type granulator. The resulting particle size is preferably 1.05 to 14 mm.

Next, to produce the granulated product thus produced, use a rotary kiln or the like. - can also be done, but with this device Id゛*+'7', pulverization is likely to occur in the formation of 1trS, and r, +! l! Since there are 11 and 1 directions that are easy to attach, the airflow firing method and method of patent application No. 75522/1983 and patent number 1.0/3166 of 1983 are applied.
If a furnace is used, the granules are rapidly heated at the initial stage of feeding, so the surface of the granules is immediately sintered, there is less pulverization of the granules, and the I/O of the granules is reduced. llI! It is possible to make fired products with a light specific gravity without any need for a spear.

The firing temperature of the granules varies depending on the amount of dehydrated cake added and the specific gravity of the desired product, but is between 1.000 and 1.200°C.

According to the present invention, the sewage sludge incineration ash discharged from the sewage treatment plant and the dewatered cake of sewage sludge are used as raw materials to produce high-strength sintering with low specific gravity, without using materials other than sewage sludge. Its industrial value is great because it can make things.

Sewage sludge incineration ash, which has the composition shown in Table 1 and is discharged from the sewage treatment yq■r iH and is treated without using lime, is
The incineration ash was pulverized to 90π passing through a 200-mesh sieve, and 45 parts by weight of dehydrated sewage sludge cake (water content 55%) to be discharged at the same sewage treatment plant was added and kneaded to 100 parts by weight of the pulverized incineration ash. Granules with a diameter of 5 to 15 mm were prepared and dried. The granulated dried product obtained in this way had a crushing strength of 911 (mm) for grains with a diameter of 10mm.The crushing strength of the dried granulated product was 911 (mm) when fired in an electric furnace.As shown in Table 2, Sintered granules with low specific gravity were obtained.

2nd table size/IG' of spherical sintered granule sample 1; -812
Crushing + M'j degree surname 1: 37.9% Hashi)
Strong+”y large sintered granules! I got 1.

4 drawings jyi゛r? Figure 1 shows the relationship between the amount of dewatered cake of sewage sludge added to sewage sludge ash and the pressure of 5119 grains of 611-strong dust; Amount of dehydrated cake of sewage sludge added to incineration ash and degree of calcination equal to 4:+
', r, shows the relationship between the specific acid of the product.

In Figure 2, 1, 2:I:, - and 3 are respectively known;
Acid type]. 0,1. ．． 2 O': and 1.4 cases are shown.

7- 1 diagram

Claims (1)

[Claims] qlt of F water sludge, add the same sewage/F) dehydrated cake to the ash, adjust the water content and crush it, then use the furnace to achieve 71!1 characteristics. sewage sludge j13
'7 How to dispose of ash.