JPH0229620B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing lightweight aggregate using sludge containing combustible materials such as sewage sludge as a raw material.

(Prior art) Conventionally, in order to manufacture lightweight aggregates using sludge such as sewage sludge as a raw material, auxiliary materials such as bentonite, clay, and shale have been added to increase granulation strength, expandability, and foamability. After adding sludge to the raw material, binders such as lignin, CMC, PVA, and water glass are added to granulate it, and the granules are sintered using external heat in a rotary kiln, airflow combustion furnace, etc. Therefore, it required large amounts of auxiliary raw materials, binders, and fuel, which had the disadvantage of increasing equipment costs, running costs, and manufacturing costs. In addition, the purpose of producing lightweight aggregate using sludge as a raw material is to reduce the volume and weight of the generated sludge, stabilize it so that heavy metals do not elute, and facilitate the reduction and securing of disposal sites, as well as the effective use of sludge. However, the conventional manufacturing method has the disadvantage that the amount of lightweight aggregate generated is extremely large compared to the amount of sludge generated.

(Objective of the Invention) The present invention solves the above-mentioned drawbacks and reduces the amount of auxiliary raw materials, binders, fuel, etc. used, thereby reducing equipment costs, running costs, and manufacturing costs, and also reduces the amount of materials generated in various industries. This was completed with the aim of producing a lightweight aggregate using sludge containing combustible materials as a raw material, which would enable the disposal and effective use of sludge, which is difficult to treat and dispose of.

(Structure of the Invention) The present invention incinerates sludge while leaving a part of the combustibles contained therein to reduce the calorific value of the sludge to 150 to
The granules are adjusted to 500 Kcal/Kg, granulated to a required size, and then stacked in a downward suction type incinerator and sintered by self-combustion.

(Example) Next, an example of the present invention will be described in detail with reference to a flow sheet illustrating a flow sheet. 1 is a dehydrated sludge silo that stores sludge containing combustible materials such as dehydrated sludge generated in a sludge treatment plant. The dehydrated sludge supplied from the dehydrated sludge silo 1 to the incinerator 2 is incinerated in this incinerator under a reducing atmosphere, but at this time, the combustibles contained in the dehydrated sludge are not completely incinerated and the combustibles The incinerated ash is incompletely incinerated so that a portion of the combustible material remains, and the incinerated ash with some combustible material remaining is crushed or crushed and stored in the incinerated ash silo 3. Reference numeral 6 denotes a classifier for classifying the incinerated ash supplied by the incinerated ash silo 3, in which some combustible materials remain. The incinerated ash is once classified into coarse incinerated ash powder, in which particles account for 80 to 90%, and incinerated ash fine powder, in which particles of 44 microns or less account for 20 to 30%, and are stored separately in coarse powder silo 7 and fine powder silo 8. Then, the amount of combustible substances contained in both the coarse powder and the fine powder is measured, and the ratio is set using the mixing ratio setting device 9 so as to obtain the optimum mixing ratio considering both granulation and combustion. Coarse powder and fine powder are quantitatively fed into the mixer 11 from the weighing machine 10 according to the ratio, and the coarse powder and fine powder are mixed to form a raw material powder whose calorific value is adjusted to, for example, 150 to 500 Kcal/Kg. do. The amount of combustible substances in the raw material powder having a calorific value of 150 to 500 Kcal/Kg varies depending on the type of sludge, but is generally about 5 to 15% by weight. Next, this raw material powder is fed to a water supply machine 12.
A humidified kneading machine such as a pug mixer 1 is supplied with water by
In Step 3, the water content is humidified and kneaded so that the moisture content is 5 to 20% by weight, primary aggregation for granulation is performed, and then a predetermined proportion, for example 2 to 5%, of the raw material powder is added to further increase the granulation strength. The binder is supplied as needed from the binder silo 14, and then humidified and granulated in a granulator 15 such as a pan-type pelletizer to obtain particles with a moisture content of 10 to 25% by weight and a desired size of 0.3.
Granulate and dry to ~20 mm granules. Next, classifier 1
This is a downward suction type incinerator in which a box-shaped sintering cart 21 having a grate 17 at the bottom moves the classified granules to a predetermined particle size in a step 6 over a large number of wind boxes 22. The filling machine 18 stacks the sintered cart 21 to a thickness of 200 to 400 mm, and the sintered cart 21 loaded with the stacked material is guided to the ignition chamber 19 by the drive device 23, and the stacked material is The surface of the ignition is initially ignited by the ignition burner 20, and during the transition from the ignition chamber 19, 50 to 150 mmAq is ignited by the exhaust gas fan 24 from the wind box 22.
If the combustible materials in the stacked granules are self-combusted by aeration while sucking them downward, the combustible materials will be burnt out and the incineration ash in the granules will be sintered and become porous granules. , this porous granular material is sintered into a trolley 2
1, the aggregate is discharged and stored in an aggregate silo 25 as lightweight aggregate. The conditions necessary for the sintering are, for example, maintaining the temperature at 1000 to 1100°C for several minutes, blowing high-temperature hot air downward to dry the granules in the lower layer, and drying the surface layer of this stack. The granules in the sintering cart 21 are self-combusted, and the granules in the sintering cart 21 are then ignited to move the combustion position downward one by one until the combustion position reaches the grate 17 surface. Sintering of all layers is completed.

The raw material powder used in the present invention is incinerated ash obtained by incinerating waste such as municipal garbage and various dehydrated sludge such as sewage sludge, leaving a part of the combustible materials contained therein. If the calorific value is less than 150 Kcal/Kg, the energy required for the granules to self-combust and sinter will be insufficient, and there will be a large amount of unburned parts, which may reduce the crushing strength. If it exceeds 500Kcal/Kg, there is a risk that the granules will melt and form clinker, so if the calorific value exceeds 150Kcal/Kg,
It is preferable to use raw material powder obtained by incinerating sludge with some combustibles remaining so that the amount becomes 500 Kcal/Kg. Furthermore, in the examples, incinerated ash is classified into coarse incinerated ash powder and fine incinerated ash powder, and both are mixed, but this is because there is generally a difference between the particle size of incinerated ash and the amount of combustible material in the coarse powder. This is because the amount of ash is large and the amount of combustible material is small in the fine powder, and it is easier to mold when the fine powder and coarse powder are compatible. In some cases, it may be sufficient to simply cut the particles below or above a predetermined particle size, or in extreme cases, they may be left as they are. In addition, in order to have granulation strength to the extent that the granules do not easily break during granulation and drying, for example, CMC, PVA, water glass, etc. should be added by 0 to 5 weight percent based on the raw material powder, as shown in the examples. It is preferable to coat or mix the surface of the granulated material by adding about %.

(Effects of the Invention) As is clear from the above description, the present invention uses incineration ash containing unburned materials obtained by incinerating sludge with some of the combustible materials contained therein as a raw material powder, and produces this raw material powder. After granulation, the material is piled up in a downward suction type incinerator and sintered by self-combustion to obtain lightweight aggregate, which does not require large amounts of auxiliary raw materials or binders other than the raw material sludge. Since the incineration ash obtained by incompletely incinerating the raw material sludge does not require the use of auxiliary raw materials, there is little need to increase the amount of sludge to be disposed of; Since the combustibles are evenly dispersed in the powder, a versatile porous lightweight aggregate with excellent pore dispersion is obtained, and the trouble of mixing combustibles with the incineration ash can be eliminated. This is combined with the advantage that it is possible to significantly save fuel and reduce manufacturing costs, and the surplus heat generated in the sludge incineration process can be recycled and used in the granule drying process and sintering process. As it solves the problems of the conventional lightweight aggregate production method, it will greatly contribute to the development of the industry.

[Brief explanation of drawings]

The drawing is a flow sheet showing an embodiment of the invention.

Claims (1)

[Claims] 1 The sludge is incinerated leaving a part of the combustibles contained in it to adjust its calorific value to 150 to 500 Kcal/Kg, granulated to the required size, and the granulated material is sucked downward. A method for producing lightweight aggregate, characterized by stacking it in a type of incinerator and sintering it by self-combustion.