JPS5849319B2 - Pretreatment method for cement solidification treatment for incineration ash and dust - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pretreatment method for solidifying incineration ash and dust generated when trash, waste, etc. are incinerated into cement.

Conventionally, the method of disposing of incinerated ash and dust was to simply dispose of it in a landfill, but since incinerated ash and dust are fine particles, they easily cause dust pollution.
In addition, there was a high risk that the harmful heavy metals contained therein would leach out and cause secondary pollution, such as causing damage to the human body.

For this reason, plastic solidification methods, calcination methods, melting methods, etc. have been proposed as a means of preventing secondary pollution from such incineration ash, dust, plating sludge, etc., but they are not stable. The solidification treatment method using cement is generally used because the treatment cost is low and the operation is simple.

However, conventional cement solidification methods use ordinary Boltland cement or add special chemicals, but none of them are sufficiently effective when processing incineration ash and dust. The current situation is that they are not fully demonstrating their potential.

In other words, when solidifying plating sludge etc. with cement, the sludge etc. is reliably mixed with the cement components,
Eiwa reaction by cement components occurs quickly, and a cement solidified product with high strength is obtained in a relatively short period of time, and sludge, etc. can be reliably treated, but incineration ash and dust may contain various types of Due to the presence of active substances caused by metal oxides, this inhibits the hydration reaction of cement components, making it difficult for cement to solidify sufficiently. For example, the obtained cement solids weigh 10 kg in 28 days. /cw
It has only a uniaxial compressive strength of about t, and there are problems such as it easily dissolves into sand when immersed in water.
It is inconvenient not only to use the solid cement as a product but also to dispose of it in a landfill.

Additionally, there is a problem that the inhibitory effect on the cement hydration reaction by the active components in such incinerated ash and dust is greater when the incinerated ash is left for a longer time than immediately after it is generated. Therefore, there has been a strong demand for the development of a method for reliably disposing of incinerated ash and dust.

The present invention has been developed in view of the above circumstances, and its purpose is to easily and reliably solidify incinerated ash and dust into cement, and to provide a cement with high strength and without the inconvenience of dissolving in water. An object of the present invention is to provide a pretreatment method for cement solidification treatment of incineration ash and dust, which makes it possible to obtain cement solids.

That is, as a result of intensive study on the method for treating incinerated ash and dust, the present inventors added water to the incinerated ash and dust in advance, added a caustic alkali such as sodium hydroxide and potassium hydroxide, and thoroughly stirred and mixed the mixture. When a pressure contact reaction is carried out and, if necessary, a pressure state exceeding normal pressure is maintained, a hydration reaction occurs, which is a crystal water formation reaction of metal oxides containing slurry of incinerated ash and dust. (This phenomenon is called a hydrothermal reaction).As a result, the incinerated ash and dust expand into a slurry, and the fine particles in the incinerated ash and dust are expanded. Active ingredients (mainly hydrogen and carbon monoxide) that impede cement solidification contained in the air bubbles
is emitted from incinerated ash and dust and becomes inert, and when mixed with cement, a cement solid that exhibits great strength can be obtained in a short period of time, and the present invention has been developed based on the discovery that incinerated ash and dust can be reliably treated. In the present invention, when incinerated ash, dust, or a mixture thereof is solidified into cement, water and caustic alkali are added to the incinerated ash, dust, or a mixture thereof in advance, and a pressurized contact reaction is carried out. The present invention is characterized in that the temperature of the slurry of the incinerated ash, dust, or a mixture thereof is increased.

The present invention will be explained in more detail below.

The incineration ash treated by the present invention is generated when garbage and waste are incinerated, and the dust is used in waste heat boilers, cyclones, multi-cyclones, bag filters, etc.
Soot, dust, etc. collected by electrostatic precipitators, etc.
These may be immediately after being incinerated or collected, or may be left for a long period of time.

When the above-mentioned incineration ash or dust or a mixture thereof is to be solidified into cement, water is first added to the incineration ash or dust, and sodium hydroxide,
A caustic alkali such as potassium hydroxide is added and a pressurized contact reaction is carried out using a two-der kneader or the like.

In this case, the mixing ratio of each component is incineration ash, dust, 10 parts
It is preferable to use 20 to 40 parts by weight of water and 4 to 10 parts by weight of caustic alkali to 0 parts by weight, and a sufficient pressurized contact reaction is normally carried out at a mixing ratio within this range, thereby causing incinerated ash, The temperature of the dust slurry increases to ensure that its active ingredients are inactivated.

Incidentally, if necessary, it is also possible to blend caustic alkali in an amount exceeding the above upper limit.

Further, the pressurized contact reaction time using the kneader is preferably 5 to 10 minutes, and after the pressurized contact reaction, the slurry is stored in a heat storage container under pressure for usually 1 to 2 hours as necessary. The mixture is left to stand to generate a high temperature of 100'C or higher to carry out a hydrothermal reaction.

In this way, by adding water and even caustic alkali to the incinerated ash and dust and causing a pressurized contact reaction in the mixer, the temperature of the slurry of incinerated ash and dust increases, and the 100-120 by holding in a pressurized state
The temperature rises to approximately 0.0°C, and as a result, the active ingredients such as metal oxides in the incinerated ash and dust undergo a hydrothermal reaction, the slurry expands, and the active ingredients are inactivated.

Then, using the slurry of incinerated ash and dust whose active ingredients have been rendered inactive by the above pretreatment, cement solidification treatment is performed in a conventional manner.

That is, 20 to 30 parts by weight of ordinary water and 15 to 30 parts by weight of cement are mixed with 100 parts by weight of the above slug IJ-1, and solidified by pressure molding.

The solidified material obtained in this way is strong in a short period of time, for example, has properties equivalent to general concrete bricks having an unconfined compressive strength of about 100 kg/crA after 3 days of age, and is soluble in water. There's nothing you can do about it, and it's useful.

As explained above, the present invention provides incineration ash and dust with water,
By adding caustic alkali and causing a pressurized contact reaction, the active ingredients in the incineration ash and dust are inactivated.
Therefore, incineration ash and dust are effectively pretreated and can be easily and reliably solidified into cement.
A solidified or molded product that exhibits great strength in a short period of time and can be effectively used without the inconvenience of dissolving in water can be obtained, and incineration, which was the only disposal method and caused secondary pollution, could be obtained. Ash and dust can be effectively returned to society.

EXAMPLES Hereinafter, the present invention will be explained in more detail by showing Examples and Comparative Examples.

Example Using dust that could not be sufficiently treated by cement solidification treatment by the method of the comparative example described later, 30 parts by weight of water and 7 parts by weight of sodium hydroxide were added to 100 parts by weight of this dust.
Parts by weight were added, a pressurized contact reaction was carried out for 10 minutes using a pressure mixer, and when the mixture was left under pressure for 2 hours, the temperature rose to about 110°C.

After the reaction was completed, 20 parts by weight of water and 15 parts by weight of cement were added to the mixture and the material was compressed and solidified.
It had an unconfined compressive strength of kg/cr7f, did not have the disadvantage of dissolving in water, and exhibited properties equivalent to ordinary concrete bricks.

Comparative Example Using 100 parts by weight of dust, 25 parts by weight of water and 40 parts by weight of cement were added to perform compression solidification.

The material obtained had a uniaxial compressive strength of only 10 kg/crti after 28 days of age, and was extremely brittle, dissolving into sand when immersed in water. Ta.

From the above results, by adopting the pretreatment method for cement solidification treatment according to the present invention, dust can be reliably treated and cement solidified products with high strength and without inconveniences such as dissolution in water can be easily produced. It is found that this can be obtained.

Claims (1)

[Claims] 1. When incinerated ash, dust, or a mixture thereof is subjected to cement solidification treatment, water and caustic alkali are added to the incinerated ash, dust, or a mixture thereof in advance to carry out a pressurized contact reaction. A pretreatment method for cement solidification treatment of incinerated ash and dust, which comprises raising the temperature of a slurry of the above-mentioned incinerated ash, dust, or a mixture thereof. 2 ・Incineration ash or dust or a mixture thereof10
0 parts by weight to 20 to 40 parts by weight of water and 4 parts by weight of caustic alkali
Claim 1: ~10 parts by weight are mixed.
A pretreatment method for cement solidification treatment for incineration ash and dust described in Section 1.