JP3511609B2 - Melt processing method of mixture of incineration ash and fly ash - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melt processing method for a mixture of incinerated ash and fly ash. Incineration ash of municipal waste and industrial waste, fly ash generated when incinerating these is melted in a melting furnace such as an arc furnace, plasma arc furnace, resistance furnace, induction furnace or burner furnace to reduce the volume. It is made to be harmless and harmless. The present invention relates to a method for melting and treating a mixture of incinerated ash and fly ash as described above in a melting furnace.

[0002]

2. Description of the Related Art Conventionally, as a method for melting a mixture of incinerated ash and fly ash, the incinerated ash and fly ash stored in a hopper are cut out by a pusher or a rotary valve and dropped on a conveyor. Is carried to the melting furnace by the conveyor and charged. However, the conventional method has the following drawbacks. 1) The incinerated ash contains a considerable amount of water because it is humidified by sprinkling water or the like in order to prevent the incineration ash from scattering and reburning and making it easy to handle. Since such incinerated ash has a strong adhesiveness and a large angle of repose, it easily adheres to a hopper, a conveyor, etc., and a bridge phenomenon occurs in the hopper, often causing clogging. When the incinerated ash has a high water content, sodium hydroxide is produced from the sodium component in the incinerated ash, and when the incinerated ash and fly ash are mixed, sodium hydroxide reacts with metallic aluminum or zinc in the fly ash. Since it produces hydrogen gas, it is extremely dangerous. 2) The conventional method of cutting out the incineration ash and fly ash stored in the hopper with a pusher or a rotary valve is a so-called constant volume method in which the incineration ash and fly ash that have fallen from the hopper into a certain space below the hopper are cut out. Therefore, when the bulk specific gravity of incinerated ash or fly ash changes, or their level in the hopper changes, the cut-out weight of both changes, and the input weight to the melting furnace also changes. As a result, the melting temperature in the melting furnace fluctuates, and the discharge of the generated molten slag becomes unstable. 3) Because the incinerated ash and the fly ash that have been cut out are simply dropped onto the conveyor and both are not sufficiently mixed, this is because the composition of the waste to be put into the melting furnace is uneven. In the melting furnace, the amount of volatilization increases temporarily, or partially unmelted incinerated ash or fly ash remains and these are discharged together with the molten slag.

[0003]

The problem to be solved by the present invention is that the conventional method has the drawbacks of 1) to 3) as described above, and in the end, in the conventional method, incineration ash and fly ash are continuously produced. The point is that the melt processing cannot be performed stably.

[0004]

SUMMARY OF THE INVENTION In the present invention, however, incinerated ash that has been dried to a water content of 12% by weight or less and fly ash are cut out separately, and the respective weights are weighed and then both are mixed. The present invention relates to a melting treatment method for a mixture of incinerated ash and fly ash, which is characterized in that a mixture having a uniform composition is charged into a melting furnace by mixing with a machine.

The incineration ash to be subjected to the melting treatment in the present invention is an incineration residue such as municipal waste or industrial waste. As described above, such incinerated ash is usually humidified for easy handling. Further, fly ash is a trapped substance that is volatilized together with the exhaust gas and captured by the dust collector when the above-mentioned municipal waste is incinerated. Such fly ash has a moisture content of almost 0% at the time of capture, has a very small particle size (1 to several tens of μm), and has the property of easily re-evaporating harmful substances by reheating, and is usually incinerated. A neutralizing agent such as calcium hydroxide or calcium carbonate is added to neutralize the hydrochloric acid gas generated at the time. In the present invention, the incineration ash and the fly ash as described above are simultaneously melt-processed in the melting furnace. The melting furnace used for the melting process is an arc furnace, a plasma arc furnace, a resistance furnace, an induction furnace,
For example, a burner furnace.

In the present invention, first, the incinerated ash is dried to reduce its water content to 12% by weight or less. If the water content exceeds 12% by weight, the stickiness of the incineration ash will suddenly become strong and the angle of repose will also suddenly increase, making it easier to adhere to hoppers, conveyors, etc., and to cause clogging at various places during the loading process. Because it will be higher. Moreover, as the water content increases, the risk of generating hydrogen gas increases as described above.
Various types of dryers such as rotary type, belt type and tunnel type can be used for the drying treatment, but it is preferable to use a hot air rotary dryer. It is possible to mix the incinerated ash with the fly ash and then dry it.However, in this case, fine fly ash is entrained in the dry exhaust gas due to heating and agitation during drying, and is scattered again or again. Even if ash is granulated, harmful low-boiling-point substances are volatilized from the fly ash by heating at the time of drying, and as a result, the slag-forming efficiency in the subsequent melting process is reduced, and the harmful substances are rendered harmless. This is an inconvenience because it hinders the purpose.

It is advantageous that the incinerated ash is subjected to a sieving treatment prior to the drying treatment, and that which has passed through a sieve having an opening of 25 mm or less is dried. Usually, the incinerated ash is crushed and then sieved, but crushing and sieving can be performed simultaneously. In any case, while considering the economics of crushing and sieving treatment, the particle size of the incinerated ash is made finer, and by increasing the specific surface area, the drying treatment is efficiently performed, and the fly ash described later is also used. This is because the mixing can be performed more uniformly, and the melting treatment of the mixture can be efficiently performed. Various crushers and mills can be used for the crushing treatment, but it is preferable to use a hammer mill with a combination of horizontal impact shearing, and for the sieving treatment, various types of sieves such as a rotary type, a vibration type and a swing type are used. Can be used, but it is preferable to use a rotary sieve.

In the present invention, next, the incinerated ash and the fly ash which have been dried to a water content of 12% by weight or less are cut out separately and the respective weights are weighed. By weighing the weight of each of the incinerated ash and the fly ash, the cut-out weight of both and as a result, the weight of the mixture charged to the melting furnace is uniformly stabilized, and the melting temperature in the melting furnace and the discharge of the generated molten slag are stabilized. It is because it can be made into. Although the weighing means itself is not particularly limited, for example, a signal emitted from the load cell when the incinerated ash or the fly ash is conveyed by a conveyor with a scraper and put into the container received by the load cell, and the input amount becomes a constant amount. By closing the shutoff valve provided above the container between the container and the conveyor, a certain amount of incinerated ash or fly ash can be weighed in the container.

In the present invention, finally, the weighed incinerated ash and fly ash are mixed. This is because the composition of the mixture can be made uniform by mixing, and it is possible to prevent a temporary increase in the amount of volatilization in the melting furnace or a part of unmelted incinerated ash or fly ash remaining. Various types of mixers such as a rotary type, a vibration type, and an oscillating type can be used for mixing, but it is preferable to use a rotating drum type mixer.

After the incineration ash and the fly ash are mixed in this way, the mixture is put into a melting furnace. It is also possible to reweigh the mixture prior to dosing.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a process diagram showing an embodiment of the present invention. The incineration ash generated in the incinerator is crushed, sieved, and the passing material is dried. Then, the dried incinerated ash and the fly ash generated in the incinerator are cut out separately, the respective weights are weighed, both are mixed, and the weight of the mixture is re-weighed and melted.

According to the process diagram described above with reference to FIG.
A mixture of municipal waste incineration ash and its fly ash was melted. The incinerated ash was crushed with a horizontal impact shearing type hammer mill, the crushed material was sieved with a rotary sieve, and the material that passed through a sieve with an opening of 25 mm was dried to a water content of 11% by weight with a hot air rotary dryer. . The water content was measured with an infrared moisture meter. The incinerated ash thus dried and the fly ash are cut out separately, and the respective weights are weighed by the weighing means using the load cell described above, and both are in a ratio of 40 parts by weight of fly ash to 60 parts by weight of incinerated ash. Mix with a rotating drum mixer. The weight of the mixture was similarly re-weighed and then charged into an arc furnace. When such an operation was continuously carried out for one week, during that period, incineration ash was hardly attached or clogged in the charging process, the melting temperature was stable at 1200 ± 50 ° C, and the molten slag was discharged smoothly. As a result, unmelted incinerated ash and fly ash were not discharged together with the molten slag.

[0013]

As is apparent from the above, the present invention described above has an effect that the incineration ash and the fly ash can be continuously and stably melt-processed.

[Brief description of drawings]

FIG. 1 is a process drawing showing an embodiment of the present invention.

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Claims (2)

(57) [Claims] 1. An incinerator ash that has been dried to a water content of 12% by weight or less and fly ash are cut out separately, each weight is weighed, and then both are mixed with a mixer to homogenize the composition.
A method for melting a mixture of incinerated ash and fly ash, which comprises charging the mixture into a melting furnace. 2. The melting treatment method for a mixture of incinerated ash and fly ash according to claim 1, wherein the incinerated ash is subjected to a sieving treatment and passed through a sieve having an opening of 25 mm or less and dried.