JPH105616A - Slag cleaning method and slag cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily remove heavy metals that can be easily eluted from slag while facilitating treatment of wastewater after washing slag discharged from a waste melting treatment furnace. SOLUTION: A cleaning water supply unit 2 for supplying cleaning water to a cleaning tank 1 for receiving and cleaning slag discharged from a waste melting treatment furnace, and a slag discharge mechanism 3 capable of discharging slag after cleaning are provided. In a molten slag cleaning apparatus provided with a cleaning water discharge mechanism 4 for extracting and discharging a part of the cleaning water supplied from the cleaning water supply unit 2, a chelating agent was added from the cleaning water supply unit 2. It is configured to supply chelate washing water, and the chelate washing water used for the washing is used as a treatment agent for detoxifying fly ash collected from a waste treatment furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slag cleaning method for cleaning slag discharged from a waste melting furnace with water, and a cleaning water receiving a supply of cleaning water in a cleaning tank for receiving and cleaning the slag. The present invention relates to a slag cleaning apparatus including a supply unit, a slag discharge mechanism capable of discharging slag after cleaning, and a cleaning water discharge mechanism for extracting and discharging a part of the cleaning water supplied from the cleaning water supply unit.

[0002]

2. Description of the Related Art Conventionally, the disposal of slag discharged from a waste melting furnace has been carried out by simply water-cooling the granulated slag for landfill disposal by simply washing it with cooling water. In particular, when cleaning is required, water washing is repeated again at the time of carrying out.

[0003]

However, the slag discharged from the waste melting furnace in the first half contains heavy metals, which are harmful substances derived from the waste. Especially in landfills,
With respect to, for example, lead among the above heavy metals, the elution standard after disposal is strict, and the lead content per liter of eluted water is regulated to 0.01 mg or less. Therefore, in order to remove the heavy metal adhered and discharged on the surface of the slag, a process such as repeating water washing is required. In addition, the washing efficiency of heavy metals adhering to the surface of the slag is not at a desirable level by simple water washing, and it is difficult to satisfy the above discharge standards. There is a problem that processing is required. Therefore, the slag cleaning method and the slag cleaning apparatus of the present invention solve the above-mentioned problems, and can easily remove heavy metals that can be easily eluted from the slag while facilitating the treatment of wastewater after cleaning. The purpose is to provide.

[0004]

[Means for Solving the Problems]

[First Characteristic Configuration] A first characteristic configuration of the slag cleaning method of the present invention for the above object is as described in claim 1, wherein the slag discharged from the waste melting furnace is washed with water.
The point is that the cleaning is performed using chelating cleaning water obtained by adding a chelating agent to the cleaning water. [Function and effect of the first feature configuration] According to the first feature configuration, the heavy metal adhering to the slag surface is formed into a chelate complex to be trapped and removed, so that it can be effectively cleaned. In particular, in the case of treating a trace amount of heavy metal adhering to the surface, it is difficult to remove the heavy metal because mere washing with water reaches equilibrium at an early stage, but it can be almost completely removed by forming a chelate complex. . Further, since the heavy metal after removal is in the form of a chelate complex, if the chelate complex capturing the heavy metal is separated, the chelate washing water after washing can be rendered harmless, and the wastewater treatment becomes easy. Moreover, since the heavy metal trapped in the separated chelate complex is not easily dissociated, the separated chelate complex can be disposed of as harmless waste. For example, if a polymerizable solid substance is used as a chelating agent, it is possible to solidify a chelate complex that has captured heavy metals, and if solid-liquid separation is performed, the chelate washing water after washing can be rendered harmless. Will also be easier. Moreover, even if the solidified chelate complex is exposed to rainwater,
There is no danger of elution of the trapped heavy metals from the solidified chelate complex, and it is possible to dispose of the harmful waste as a harmless waste. As a result, it has become possible to easily remove heavy metals while facilitating the treatment of wastewater after washing. [Second characteristic configuration and operation and effect] According to a second characteristic configuration of the slag cleaning method of the present invention, the chelate cleaning water used for cleaning in the first characteristic configuration is discarded. By using as a treating agent for the detoxification treatment of fly ash collected from the material processing furnace, it becomes possible to effectively use the chelating agent excessively added to the chelate washing water for detoxification of the fly ash, The waste of chelating agent can be eliminated. As a result, in addition to the operation and effect of the first characteristic configuration,
The chelating agent to be used can be used effectively.

[Third characteristic configuration] A third characteristic configuration of the slag cleaning apparatus of the present invention for the above purpose is as described in claim 3, wherein a chelating agent is added to a cleaning tank from a cleaning water supply section. The point is that the cleaning water is supplied. [Third feature configuration and operation and effect] The third feature configuration enables the slag cleaning method of the first feature configuration to be implemented,
As in the case of the first characteristic configuration, the heavy metal can be almost completely removed by chelate complexing in the washing water. Furthermore, if the chelate complex capturing the heavy metal is separated, the chelate washing water after washing can be rendered harmless, and thus the wastewater treatment becomes easy. Moreover, since the heavy metal trapped in the separated chelate complex does not easily dissociate,
It becomes possible to dispose of the separated chelate complex as harmless waste. As a result, it has become possible to easily remove heavy metals while facilitating the treatment of wastewater after washing.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a slag cleaning apparatus to which the slag cleaning method of the present invention is applied will be described below with reference to the drawings. FIG. 1 shows an outline of an example of a waste melting treatment facility provided with the slag cleaning device of the present invention.
Shown in

[0007] The waste melting treatment equipment includes a waste melting furnace F, a chimney for discharging waste gas generated by melting the waste in the waste melting furnace F through a flue 13, A slag recovery water tank 10 for recovering the resulting molten slag S, and a slag cleaning device C for receiving and cleaning the slag S discharged from the slag recovery water tank 10;
Further, a fly ash detoxification treatment tank 20 for detoxifying fly ash collected from exhaust gas of the waste melting furnace F and other waste treatment furnaces is provided. The flue 13 is provided with a heat recovery facility for recovering the heat of the exhaust gas from the waste melting furnace F and an exhaust gas treatment facility provided with a dust collector for cleaning the exhaust gas. In addition, the flue 13 is provided to be branched from the slag discharge passage for keeping the molten slag S warm. The slag recovery water tank 10 is filled with cooling water, and the slag S dropped from the slag discharge passage of the waste melting furnace F above is received in the cooling water, rapidly cooled, and granulated into slag. And a slag discharge conveyor 11 that receives the granulated slag R in the cooling water and carries it out of the slag discharge unit 10a provided at a higher position on the surface of the cooling water. Since the temperature of the cooling water rises due to the heat from the slag S, the cooling water is provided with a water cooling tank 12d for cooling the cooling water, and the cooling water is circulated by a circulation pump 12c provided in a drain pipe 12b. The cooling water cooled in the water cooling tank 12d is returned from the water supply pipe 12a to the slag recovery water tank 10. Cooling water evaporated for cooling the slag S is supplied in the water cooling tank 12d.

The slag cleaning apparatus C includes a cleaning tank 1, and the cleaning tank 1 has a cleaning water supply unit 2 for receiving a supply of cleaning water and a slag discharging mechanism 3 capable of discharging slag after cleaning.
And a washing water discharging mechanism 4 for extracting and discharging a part of the washing water supplied from the washing water supply unit 2. The cleaning water supply unit 2 includes a chelating water tank 2a for supplying a chelating cleaning water 5 to which a chelating agent is added to the cleaning tank 1. The chelating water tank 2a supplies a chelating agent and cleaning water, respectively. The chelate washing water 5 is prepared by mixing and diluting in the water tank 2a. The slag discharge mechanism 3 includes a belt conveyor 3a that collects and discharges the washed slag that settles in the chelate cleaning water 5, and collects the washed slag in the chelate cleaning water 5. Thus, the cleaning water is transported to a position higher than the cleaning liquid level in the cleaning tank 1 and separated from the chelating cleaning water 5 and discharged. The washing water discharge mechanism 4 is provided with a washing water discharge pump 4 a in a discharge pipe, and sends the chelate washing water 5 toward the fly ash detoxification treatment tank 20. Chelate wash water 5 corresponding to the amount of the chelate wash water 5 sent out by the wash water discharge pump 4a is supplied from the wash water supply unit 2.

The fly ash detoxification treatment tank 20 is configured to inject chelate water from the chelate water supply unit 21 into the collected fly ash and knead the mixture, take out the kneaded fly ash, and naturally dry and solidify the fly ash. It is composed.

An example of an operation for washing and recovering slag discharged in the above-mentioned waste melting treatment facility will be described below. Description of the generation of the molten slag S in the waste melting furnace F is omitted. Exhaust gas emitted from the furnace is
The flue gas is discharged from the chimney through the stack 13 to the atmosphere. Fly ash accompanying the exhaust gas is collected by the dust collector provided in the stack 13. On the other hand, the molten slag S generated after incineration of the waste generated in the furnace is dropped from the slag discharge passage formed below the furnace into the cooling water filled in the lower slag recovery water tank 10 and quenched. It becomes crushed slag R. Since the cooling water is heated and heated with the dripping of the molten slag S, the cooling water is cooled in the water cooling tank 12d while circulating through the drain pipe 12b, the water cooling tank 12d, and the water supply pipe 12a to maintain a low temperature. It is.

The molten slag S is dropped into the cooling water and quenched, and the molten slag S is crushed during quenching and solidification to form granulated slag R. At this time, a part of the heavy metal contained in the molten slag S is dissolved in the cooling water, but the remaining heavy metal is confined in the granulated slag R solidified into a glass. The formed granulated slag R sinks in the cooling water,
It falls on a slag discharge conveyor 11 provided below the slag recovery water tank 10. The slag discharge conveyor 1
1 receives the dropped granulated slag R and transports the granulated slag R to the slag discharge unit 10a. During this time, the granulated slag R is washed by the cooling water, but the eluted heavy metal accumulates in the cooling water, so that the heavy metal adhering to the surface is accompanied by the cooling water that wets the surface of the conveyed granulated slag R. And contaminates the surface of the granulated slag R. Although not shown, in order to suppress the accumulation of the heavy metal, a part of the cooling water is extracted, and at the same time, the temperature of the molten slag S is increased by the heat of the molten slag S to replenish the cooling water which evaporates. Cooling water is supplied to the water cooling tank 12d.

The granulated slag R discharged from the slag discharge section 10a is dropped into the cleaning tank 1 of the slag cleaning device C. The cleaning tank 1 is filled with chelating cleaning water 5 supplied from a cleaning water supply unit 2. The chelate washing water 5 is adjusted by adding a chelating agent to water in the chelate water tank 2a. As the chelating agent, for example, Ashclean C-300 manufactured by Ebara Corporation can be used. Although this chelating agent is sold for fly ash treatment, it is also effective for washing granulated slag, and the chelating agent after washing granulated slag R in the washing tank 1 as described later. Since the washing water 5 is used for fly ash treatment,
Here, it is preferably used. In the chelate water tank 2a, this Ash Clean C-300 is
% Of the chelate washing water 5 is prepared. The Ash Clean C-300 has an average molecular weight of 3,000 to 500.
0 is a liquid polymer chelate compound having a property of solidifying by drying. The polymer chelate compound is a polymer substance formed by polymerizing a monomer having a bidentate ligand of the form [-CS-SH].
The granulated slag R in which the heavy metal on the surface has been taken away by the chelating agent in contact with the chelate washing water 5 has its surface cleaned and settled, and the belt of the slag discharge mechanism 3 arranged at the lower part of the washing tank 1 The slag is dropped onto the conveyor 3a and discharged out of the washing tank 1 by the slag discharge mechanism 3. On the other hand, a part of the chelate washing water 5 that has washed the granulated slag R and captured heavy metals is extracted from the washing tank 1 by the washing water discharge mechanism 4 and discharged into the fly ash detoxification treatment tank 20. It is delivered by the pump 4a. Chelate washing water 5 corresponding to the amount sent by the washing water discharge pump 4a is supplied from the washing water supply unit 2.

On the other hand, the fly ash detoxification tank 20 contains fly ash collected by a dust collector provided in the flue 13 and fly ash collected from exhaust gas of another waste treatment furnace. The chelating wash water 5, which has washed the granulated slag R and captured heavy metals, is sent out by the wash water discharge pump 4a and supplied from the chelate water supply unit 21. In the fly ash detoxification treatment tank 20, the chelate washing water 5 capturing the heavy metal is added to the fly ash charged and kneaded to form a fly ash kneaded material. This fly ash mixture is directly disposed of. In this way, it becomes possible to treat the chelate washing water 5 containing the heavy metal together with the fly ash to make it harmless.

Next, another embodiment of the present invention will be described. <1> In the above embodiment, an example was described in which a chelating water consisting of a polymer-based chelating compound diluted with water was used as the chelating washing water 5, but the chelating agent was a polymer-based chelating agent. Not only chelating compounds but also EDT
A, low molecular chelating agents such as NTA (nitrilotriacetic acid) may be used. Examples of chelating ligands are [-
CS-SH], the bidentate ligand was shown as [-CO-
OH], etc., and EDT
A, an amino group, an acetic acid group, a nitro group, or the like provided in NTA (nitrilotriacetic acid) or the like, or a carboxy group or the like may be provided as a ligand. <2> In the above-described embodiment, an example in which the chelate washing water 5 is supplied to the fly ash detoxification treatment tank 20 has been described, but the chelate washing water 5 may be treated as it is, Further, the chelate washing water 5 is supplied to the fly ash detoxification treatment tank 2.
0 to detoxify fly ash by using granulated slag R
May be processed together. <3> In the above embodiment, an example in which the granulated slag R is put into the washing tank 1 for washing is shown. However, the chelate washing water 5 is supplied from the chelating tank 2a directly to the slag collecting tank 10. Alternatively, the granulated slag R may be washed in the slag collecting water tank 10 by using the cooling water in the slag collecting water tank 10 as the chelating washing water 5. In this case, the cooling water in the slag recovery water tank 10 may be appropriately extracted and supplied to the fly ash detoxification treatment tank 20 to detoxify the fly ash. <4> In the above-described embodiment, the example in which the granulated slag from the waste melting furnace is washed is shown. However, the slag from the waste gasification and melting furnace may be treated. . Further, the slag discharged from other types of waste treatment equipment may be treated, and the equipment for producing slag is not limited. In short, the present invention is characterized in that heavy metals can be prevented from being eluted from the discharged slag. <5> In the above embodiment, an example is shown in which the slag cleaning device C including the cleaning tank 1 is installed adjacent to the slag collecting tank 10 and the slag discharged from the slag collecting water tank 10 is cleaned. However, as shown in FIG. 2, the slag hopper 15 for receiving the collected slag in the slag pit 20 is used.
The slag discharged from the slag recovery water tank 10 may be charged into the slag recovery tank 10, and the slag may be washed in the slag hopper 15 with chelate water. The slag hopper 15 may be separately conveyed from the slag recovery water tank 10 and intermittently charged with slag. In addition, the slag hopper 15 is provided with a lower lid 17 which swings and opens and closes at a lower portion,
It is only necessary that the cylinder mechanism 16 be operated by the control device to open and close the lower lid 17. Further, it is more preferable that a gutter portion 18 is provided on one of the lower lids 17 so as to guide the chelating water used for washing and discharge the chelating water to a predetermined discharge path only when necessary.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the accompanying drawings.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is an explanatory view of another embodiment of the present invention.

[Description of Signs] 1 Cleaning tank 2 Cleaning water supply unit 3 Slag discharge mechanism 4 Cleaning water discharge mechanism

Claims (3)

[Claims] 1. A slag cleaning method for cleaning slag discharged from a waste melting treatment furnace with water, wherein the water cleaning is performed using chelating cleaning water obtained by adding a chelating agent to cleaning water. How to clean slag. 2. The method for cleaning molten slag according to claim 1, wherein the chelate cleaning water used for said cleaning is used as a treatment agent for detoxifying fly ash collected from a waste treatment furnace. 3. A cleaning tank (1) for receiving and cleaning slag discharged from a waste melting treatment furnace, a cleaning water supply section (2) for receiving a supply of cleaning water, and capable of discharging slag after cleaning. A slag discharge mechanism (3) and the washing water supply section (2)
A washing water discharge mechanism (4) for extracting and discharging a part of the washing water supplied from the washing water, wherein the chelating washing water added with a chelating agent from the washing water supply section (2). A slag cleaning device configured to supply the slag.