JPS5851970A - Treatment for caking inflatable dust - Google Patents

Abstract

PURPOSE:To facilitate the discharge of gas and to stabilize inflatable salts, by mixing powdery dust recovered by a dust-collecting system in a municipal garbage-incinerating process with hydraulic cement and water, and rotation- granulating the mixture into balls having opened pores. CONSTITUTION:Portland cement, mixed cement or super-rapid curing cement may be used as hydraulic cement to be mixed in. The mixing ratio of said cement to dust is generally in the range of 5-40pts.wt. by weight of dust, ordinary in the range of 20-30pts.wt. The amount of water to be added is ordinary at 10-20wt%. A rotating cylinder-type granulating system, a plate-type rotation-granulating system, etc. may be adopted as the rotation-granulating method. The granulated balls have voids extending to 30-35%, and almost all of them are opened pores. Consequently, their breakdown or collapse caused by the pressure of gas or the crystallization of double salts is scarcely brought out.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stably solidifying expandable dust, which has a property of being easily destroyed because it expands with gas generation after solidification.

A typical example of dust that expands to generate gas after solidification is dust discharged during the municipal waste incineration process.

In the process of incinerating municipal waste, in addition to coarse incineration residue, it is transported along with exhaust gas and collected by a cyclone installed as a process after the incinerator or by a vehicle collection system such as an electric vehicle collection machine. There is recovered dust in powder form. There are various methods of incinerating municipal waste, but there are two main types: a machine furnace using a grate and a fluidized bed furnace using borax as a combustion medium. Mechanical furnace dust is generally fine, and fluidized bed furnace dust is generally coarse because it is mixed with sand, which is a heating medium accompanying exhaust gas. However, the common feature of both is that they contain Kanazawa aluminum powder and sacrificial salts derived from municipal waste.

The object of the present invention is powdered dust collected by a vehicle collection system in the municipal waste incineration process. These dusts contain cadmium, lead, and other heavy metals, and when the dusts are to be disposed of, they must be solidified to prevent these heavy metals from dispersing.

In the past, a common method for such solidification treatment was to add hydraulic cement and water to dust, mix it, and solidify it. The molding method is an extrusion molding method in which the material is extruded from a nozzle under pressure, and the molding method is to pressurize it and extrude it from a nozzle.
Pressure molding method in which the molding is carried out under pressure, briquette method in which double rolls with split molds are rotated to continuously pressurize molding, and furthermore, the amount of added water is increased to make it fluid and formwork of a certain size is formed. However, the dust generated from the above-mentioned municipal waste contains soluble salts such as metal aluminum, lime chloride, and sodium chloride9, and when adding hydraulic cement and water, metal Aluminum generates hydrogen gas by hydrolysis in alkaline regions, and soluble salts react with the chemical components of hydraulic cement to form double salts, such as Friedel salt, 3CaO1At
203, CaCl2101 (20, chloro-ethrine guide 30aO1At20a CaCtz 18 H2O
etc. These double salts are expansive compounds;
Kanetou aluminum generates watery gas, which expands the molded product and embrittles the structure of the processed product over short and long periods of time. For this reason, according to the various conventional forming force methods, since the molded product is generally a dense structure, for example, in the casting method, the molded product swells significantly due to hydrogen gas foaming, increasing the strength and pressure. Molded products have a dense shell structure, so they tend 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. The present invention provides a method for stably solidifying the above-mentioned expandable dust, and its gist is that after solidification, the gas For dust that expands due to generation or double salt, the dust is mixed with hydraulic cement and an appropriate amount of moisture, and the dust is rolled and granulated to form balls with 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 expandable dust. The hydraulic cement is ordinary Portland cement, ultra-early strength 7t.
'Lutocin l' cement, early strength portland cement,
Portland cement such as Nakaj City Portland cement, mixed cement such as blast furnace cement, silica cement, fly ash cement, and ultra-fast hardening cement can be used. The mixing ratio of the hydraulic cement to the dust varies depending on the expected strength of the ball, but it is generally in the range of 5 to 40 parts by weight, and usually 20 to 3 parts by weight, based on the weight of the dust.
It may be 0 parts by weight. The amount of water added varies depending on the aquascape suitable for granulation, the powderiness of the dust and the above-mentioned hydraulic cement, and the wettability of the dust, but is usually 10 to 20% by weight.
That's fine. Next, as a transfer granulation method, a rotating cylindrical granulation method, a dish-type rolling granulation method, etc. are used.

According to the solidification treatment method of the present invention, the dust is granulated so as to uniformly pile up the shells while being connected by the solidification effect of hydraulic cement, and the ball is released with a uniform compaction effect on the entire surface of the ball. During this process, a structure rich in open pores is formed inside the ball. The porosity of the balls thus granulated is 30 to 35%, and most of them are open pores. For this reason, the hydrogen gas generated inside the ball is easily released through the pores, and the expandable soluble matrix produced by the reaction with salts is also stably retained in the weft body, which has many voids.

Patent applicant: Onome 1 Cement Co., Ltd. Representative patent attorney: Shibu Mitsuishi (1 other person)

Claims (1)

[Claims] For dust that expands due to gas generation and double salt after solidification,
1. A method for solidifying expandable dust, which comprises mixing hydraulic cement and an appropriate amount of water and granulating the dust by rolling to form spherical particles having open pores.