JPS6048234B2 - Solidification treatment method for municipal waste dust - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stably solidifying municipal waste, which tends to be easily destroyed because it expands with gas generation after solidification.

In the process of incinerating municipal waste, in addition to coarse incineration residue, it is transported along with exhaust gas and collected in a dust collection system such as a cyclone or an electric dust collector, which is installed as a process after the incinerator. There is recovered dust in powder form.

There are various methods of incinerating municipal waste, but there are two main types: mechanical furnaces that use a grate and fluidized bed furnaces that use silica sand as the incineration medium. Mechanical furnace dust is generally fine, and fluidized bed furnace dust is associated with exhaust gas.
Generally, it is coarse because it is mixed with sand, which is a heat transfer medium. However, the common feature of both is that they contain metal aluminum powder and soluble salts derived from municipal waste. Two volumes of municipal waste, which is the object of the present invention, is powder dust collected in the dust collection system during the municipal waste incineration process.

This municipal waste dust contains cadmium, lead, and other heavy metals, and when disposing of the dust, it is necessary to solidify it to prevent the elution and diffusion of these heavy metals. Previously, this type of solidification treatment involved adding and mixing hydraulic cement and water to dust.
A common method is solidification. The molding methods include extrusion molding in which the mold is pressed out through a nozzle under pressure, pressure molding in which the mold is molded under pressure in a mold of a fixed size, and friquet molding in which double rolls with split molds are rotated to form the mold continuously under pressure. There is also a casting method in which the amount of added water is increased to make it fluid and the mixture is poured into a mold of a certain size. However, the above-mentioned municipal waste dust contains soluble salts such as metal aluminum, lime chloride, and sodium chloride, and when hydraulic cement and water are added, metal aluminum becomes hydrogen by hydrolysis in an alkaline region. The soluble salts react with the chemical components of the hydraulic cement to form double salts, e.g. Friedel salt, -3CaO).
Al2O3, CaCl)210H. O) Chloruethrine guide 3CaO,, Al2o3cacl. 18H. O
etc. These double salts are expansive compounds;
As hydrogen gas is generated by metal aluminum, the molded product expands and the structure of the processed product becomes brittle over a short and long term. For this reason, according to various conventional molding methods, the molded product is generally a dense structure, so in the case of casting molding, for example, the molded product does not swell significantly due to hydrogen gas foaming and lose its strength, and pressure molding Since a dense shell structure is formed in materials, it tends to break and collapse due to the pressure of hydrogen gas generated from inside and the double salt crystals that form and precipitate in the dense shell.This tendency is strong. The problem becomes more pronounced in denser molded products. The present invention provides a method for stably solidifying the above-mentioned municipal waste dust. It is characterized in that the dust is mixed and granulated by rolling to form spheres having open pores. The present invention will be explained in detail below.

In the solidification treatment method of the present invention, hydraulic cement is used as the cement mixed in the municipal waste dust.

The hydraulic cement includes bolt land cement such as ordinary bolt land cement, ultra-early strength bolt land cement, early strength bolt land cement, moderate heat bolt land cement, etc.
Mixed cements such as blast furnace cement, silica cement, and fly ash cement, and ultra-fast hardening cements can be used. The mixing ratio of the hydraulic cement to the dust varies depending on the expected strength of the mature ball, but generally municipal waste dust 1
The range is from 5 parts by weight to 4 parts by weight per 00 parts by weight,
Normally, 20 to 3 parts is fine. The amount of water to be added is a water amount suitable for granulation, which varies depending on the fineness of the municipal waste dust and the above-mentioned hydraulic cement, and the leakability of the dust, but is usually 10 to 2 parts by volume. Next, as the rolling granulation method, a rotating cylinder type granulation method, a dish type rolling granulation method, etc. are used. According to the solidification treatment method of the present invention, municipal waste dust is granulated so that the shells are evenly piled up while being connected by the solidification effect of hydraulic cement, and a uniform compaction effect is given to the entire surface of the sphere to form a sphere. During this process, a structure rich in open pores is formed inside the grown bulb.

Claims (1)

[Claims] 1. For 100 parts by weight of municipal waste dust that expands due to gas generation and double salt after solidification, 5 to 40 parts by weight of hydraulic cement and 10 to 20 parts by weight of water are mixed and the dust is granulated by rolling. , a method for solidifying municipal waste dust, characterized by forming it into mature balls having open pores.