JP3551960B2 - Treatment of soil contaminated with organic matter - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method for treating soil contaminated with organic matter, which can use soil contaminated with organic matter such as oil or trichlorethylene as a part of a cement raw material and a part of a cement burning fuel.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, most of waste materials discharged in association with industrial activities have been disposed of by dumping in landfills or incineration by incinerators. Soil contaminated with oil generated from an oil refining factory site and soil contaminated with organic substances such as trichlorethylene used for cleaning (hereinafter referred to as "organic substance contaminated soil") have been disposed of in the same manner.
[0003]
However, in recent years, the capacity of landfills has been lacking, and it has become difficult to secure new landfills due to social constraints. ing. Also, incineration treatment by an incinerator is becoming difficult to implement due to a large load on the environment.
[0004]
Against this background, from the viewpoint of environmental protection, recycling of organic-contaminated soil is an important social issue as well as waste materials such as plastics and sewage sludge. The use of organic contaminated soil as a raw material is being promoted.
[0005]
[Problems to be solved by the invention]
When using organic-contaminated soil as a cement raw material, it is mixed with other cement raw materials in the raw material mixing stage as it is (that is, the cement raw material mixed with the organic-contaminated soil is passed through a raw material drying and crushing process). The components may evaporate and adhere to the electrodes of the electrostatic precipitator, which may significantly reduce the performance of the electric precipitator or generate odor.
[0006]
Therefore, it is conceivable that the organic matter-contaminated soil is directly fed into a rotary kiln of a cement burning facility without passing through a raw material drying and grinding step. However, if organic matter-contaminated soil is directly injected into the rotary kiln, it is possible that the remarks of several millimeters or more contained in the soil will adversely affect the quality of the cement clinker. Also, when a large amount of organic contaminated soil is put into the rotary kiln, there is another problem that the composition of the powder raw material prepared in the raw material process and the composition of the cement clinker are greatly different.
[0007]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for treating an organic substance-contaminated soil that can utilize the organic substance-contaminated soil as an effective resource without affecting the quality of the cement clinker. It is another object of the present invention to provide a method for treating organic contaminated soil, which can prevent the composition of cement clinker from being affected even when a large amount of organic contaminated soil is put into the cement firing step.
[0008]
[Means for Solving the Problems]
The method for treating organic-contaminated soil according to the first aspect of the present invention is characterized in that, when a cement raw material is pulverized by a dry mill and preheated by a pre-heater, and then put into a cement kiln rotary kiln to produce a cement clinker, After adding a solvent for imparting fluidity and pulverizing with a wet mill, the mixture is put into a cement firing step under a high temperature atmosphere of 800 ° C. or more, and the organic components of the organic contaminated soil are consumed as a part of fuel. In addition, the organic matter-contaminated soil is disposed of by utilizing a soil component as a part of a cement raw material .
[0009]
Here, as an example of the organic substance which is a pollutant, an oil component such as gasoline or petroleum can be considered, but trichloroethylene used as a cleaning agent can also be considered. In the case of pulverization with a wet mill, the temperature does not rise due to the pulverization. Therefore, even when the organic substance is a substance having a low boiling point such as trichloroethylene, the organic substance-contaminated soil can be mixed and pulverized with the solvent while preventing vaporization.
[0010]
As described above , the organic component can be consumed as a part of the fuel by introducing the mixed and crushed material of the soil contaminated with the organic matter and the solvent in the cement firing step under the high temperature atmosphere of 800 ° C. or more, and the soil component is reduced to the cement content. As a part of the raw material (part of the clay), it can be used for the production of cement clinker. Therefore, it is possible to dispose the organic matter-contaminated soil while making effective use of it, and to save the clay content as a cement raw material and the fuel for firing. In addition, since the organic-contaminated soil is mixed and pulverized with a solvent in a wet mill, the rek components (stones, etc.) contained in the soil can be reliably pulverized finely, so that the quality of the cement clinker is not adversely affected. In this case, the wet mill is not provided in the dry cement manufacturing equipment, and is provided separately.
[0011]
Here, when the slurry-like mixed and pulverized product coming out of the wet mill is fed into the cement firing step, it may be fed as it is in a slurry state, or may be solid-liquid separated to form a solid content into a cake. May be thrown. In the case of solid-liquid separation, the separated liquid can be reused as a solvent. When the contaminating organic substance is oil and water is added as a solvent, oil-water separation is performed, the oil is used as a fuel, and the slurry can be used as it is.
[0012]
In addition, before being put into a wet mill, the organic-contaminated soil is mixed with a solvent with stirring, and then sieved to separate and recover soil with a small organic content such as oil having a large particle size on a sieve mesh, and used as a raw material for cement. It is also possible to put in the pulverization and drying step and to put only the soil under the net with a fine particle size and a lot of organic content into the wet mill. Further, soil having a large particle size on the sieve net may be pulverized by a crusher and then charged into a wet mill.
[0013]
The method for treating organic contaminated soil according to the second aspect of the present invention is a method for treating the organic contaminated soil in the method according to the first aspect, wherein a charging point of the pulverized material of the organic contaminated soil is provided in a kiln bottom of a rotary kiln, a calciner provided in a preceding stage of the rotary kiln, a rotary kiln. It is characterized in that it is at least one of the high-temperature portions of the preheater located in the preceding stage.
[0014]
It is sufficient that the pulverized material of the organic substance-contaminated soil is charged at a temperature higher than the ignition temperature of the organic substance contained therein. By doing so, the contained organic component can be reliably burned.
[0015]
According to a third aspect of the present invention, there is provided the method for treating organic-contaminated soil according to the first or second aspect, wherein the solvent is at least one of waste oil, waste liquid, sludge, water, and a fluidizing agent. .
[0016]
Here, examples of the waste liquid include a waste liquid discharged from a pulp mill, milk, drinking water, alcohol, and the like collected from markets and the like. In addition, as the sludge, sludge coming out of a sewage treatment plant or the like can be considered. As the fluidizing agent, a water reducing agent (surfactant) that mainly reduces the amount of added water can be considered.
[0017]
The method for treating soil contaminated with organic matter according to the invention of claim 4 is the method according to any one of claims 1 to 3, wherein at least one of calcium carbonate, slaked lime, quicklime, and lime-based waste is mixed in addition to the solvent. It is characterized by the following.
[0018]
In this case, since the calcium carbonate, slaked lime, quicklime, and lime-based waste are almost cement components, the raw material composition can be appropriately adjusted even when a large amount of organic contaminated soil is put into the cement firing step. it can.
[0019]
The method for treating soil contaminated with organic matter according to the invention of claim 5 is characterized in that, in any one of claims 1 to 4, the soil contaminated with organic matter includes soil contaminated with dioxins as organic matter. That is, the organic substance contaminated soil may be an organic substance contaminated soil containing dioxins.
[0020]
In this case, the dioxins are heated in an atmosphere of 1450 ° C. or more for several tens of minutes or more when producing the cement clinker, and thus can be reliably decomposed into harmless substances. Incidentally, dioxins can be decomposed by staying in a high-temperature atmosphere of 800 ° C. or more for 2 seconds or more.
[0021]
Also, the inside of the kiln becomes 800 to 1100 ° C., the inside of the calciner becomes 800 to 900 ° C., and the high temperature part of the preheater, for example, the lowermost cyclone is 800 to 900 ° C. (when there is no calciner) Therefore, even if the dioxins are introduced into any of these places, the dioxins can be decomposed into harmless substances 2 seconds or more after the introduction.
Therefore, the organic matter contaminated soil containing dioxins can be effectively used as cement, and the environment can be improved by decomposing dioxins into harmless ones.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an outline of a cement production facility for carrying out the treatment method of the present invention. In the figure, this cement production equipment is provided with a dry mill 1, a raw material silo 2, a preheater 3, a rotary kiln 5, and an electric dust collector 10.
[0023]
The cement raw material (limestone, clay, silica stone, iron raw material) G is introduced into the dry mill 1 via a dryer as required. These raw materials G are pulverized by the dry mill 1 and introduced into the raw material silo 2, after which they are preheated by the preheater 3, then put into a rotary kiln 5 for cement firing and fired to become a cement clinker.
[0024]
The preheater 3 is a multi-stage cyclone type in which a plurality of cyclones 3a, 3b, 3c, and 3d are connected in multiple stages from the bottom to the top. Preheat to temperature (800-900C). The rotary kiln 5 has a horizontal cylindrical kiln shell inclined slightly downward to the downstream side. The preheater 3 is heated by the burner 6 using heavy oil or fine coal as fuel while rotating the kiln shell around its central axis. The cement raw material is heated to a temperature of 1450 ° C. or more to cause a sintering reaction to produce a cement clinker. Thereafter, the clinker is cooled by the cooler 7 connected to the kiln front 5A of the rotary kiln 5 and sent to the finishing step. The above is the same as the operation in a normal cement factory.
[0025]
In addition to this equipment, a wet mill 11 and a slurry pump 12 are newly added to this equipment in addition to the usual cement production equipment. The slurry pump 12 is used to directly feed the kiln bottom 5B of the rotary kiln 5 using the slurry pump 12.
[0026]
Next, a method of treating soil contaminated with organic matter will be described.
First, a solvent B for imparting fluidity is added to the organic substance-contaminated soil A, and the soil is pulverized by a wet mill 11. Thereafter, the cement clinker is manufactured by putting the mixture into the kiln bottom 5B of the rotary kiln 5 of the cement baking facility in a high-temperature atmosphere of 800 to 1100 ° C. Therefore, the mixed and crushed material C of the organic substance-contaminated soil A and the solvent B charged into the kiln tail portion 5B of the rotary kiln 5 is fired together with the heated cement raw material and discharged as a cement clinker.
[0027]
By putting the mixed and crushed material C of the organic matter-contaminated soil A and the solvent B into the kiln bottom 5B of the rotary kiln 5 in this manner, the organic components can be consumed by the rotary kiln 5 as a part of the fuel, Can be used as a part of cement raw material (part of clay) for the production of cement clinker.
[0028]
Therefore, it is possible to dispose the organic substance-contaminated soil A while effectively utilizing the soil, and it is possible to save the clay content as a cement raw material and the fuel for firing. In addition, since the organic matter-contaminated soil A is mixed and pulverized with the solvent B by the wet mill 11, the rek components (stones and the like) contained in the soil can be finely pulverized, and the quality of the cement clinker is not adversely affected.
[0029]
As the solvent B in this case, it is desirable to use at least one of waste oil, waste liquid, sludge, water, and a fluidizing agent. As the waste liquid, a waste liquid from a pulp mill can be used, and as the sludge, sludge from a sewage treatment plant can be used. As the fluidizing agent, a water reducing agent (surfactant) that mainly reduces the amount of added water can be used. By using these solvents, fluidity can be imparted to the organic substance-contaminated soil A, so that mixing and grinding in the wet mill 11 can be performed smoothly and reliably.
[0030]
In addition, calcium carbonate, slaked lime, quicklime, lime-based waste and the like may be mixed in addition to the solvent B. In such a case, almost all of them become cement components, so that they can be disposed of effectively and cement clinker can be used. While maintaining the composition in an appropriate range, a large amount of organic contaminated soil can be introduced.
[0031]
Here, when the slurry-like mixed and crushed material C coming out of the wet mill 11 is charged into the kiln tail portion 5B of the rotary kiln 5, as described above, it may be charged in a slurry state, It may be put into a cake after being separated. In the case of solid-liquid separation, the separated liquid can be reused as the solvent B.
[0032]
In addition, before being put into the wet mill 11, the organic-contaminated soil is stirred and mixed with a solvent, and then sieved to separate and collect the soil having a large particle size and a small amount of organic matter on the sieve net. The wet mill 11 may be used only for the drying step, in which only the soil under the net and having a large particle size and a large amount of organic matter is fed to the wet mill 11.
[0033]
Next, examples of the processing method will be described.
<< Treatment method 1 >>
Water (30 to 300% by weight) and a fluidizing agent (0 to 10.0% by weight) are added to soil containing an oil content of 0.1% to 30% (weight ratio), and the mixture is put into a wet mill 11; Mill for about 1-60 minutes. The slurry mixture and pulverized material thus obtained is directly charged into the kiln tail 5B of the rotary kiln 5. Alternatively, after the mixed and ground slurry is dehydrated, the obtained cake is put into the kiln tail 5B of the rotary kiln 5, and the oil-mixed water is reused as a solvent.
[0034]
<< Treatment method 2 >>
Water (30 to 300% by weight) and a fluidizing agent (0 to 10.0% by weight) are added to soil containing 0.1% to 30% (weight ratio) of an oil component, and the mixture is opened to a mesh size of 0.1%. It is poured into a 5-2.0 mm trommel (sieve) and washed with stirring for about 1 to 60 minutes. The net material thus obtained is used as a cement raw material from the raw material drying and pulverizing step. In addition, after the mesh material is pulverized by the wet mill 11, the mixed and pulverized material in a slurry state is directly charged into the kiln tail portion 5 </ b> B of the rotary kiln 5. Alternatively, after the mixed and ground slurry is dehydrated, the obtained cake is put into the kiln butt 5B of the rotary kiln 5, and the oil-mixed water is reused as a solvent.
[0035]
In the case of a cement firing facility having a calcining furnace, the mixed and crushed material C can be put into a calcining furnace instead of being put into the kiln tail of the rotary kiln. It can be put into both furnaces. In addition, as long as a temperature of 800 ° C. or more can be ensured, it can be put into the high temperature part of the preheater. In this case, if there is no calciner, it is preferable to put the mixed and crushed material C between the kiln butt 5B where the temperature is the highest and the cyclone 3a at the lowest position, or into the cyclone 3a at the lowest position. .
[0036]
In FIG. 2 and FIGS. 3 and 4, which will be described later, reference numerals 21 and 31 correspond to the raw material supply passage 21 and the exhaust gas passage 31 of FIG. 1, respectively. 2 to 4, solid arrows indicate the flow of the raw material, and broken arrows indicate the flow of the gas. Also, the same components as those shown in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and description thereof will be omitted.
[0037]
FIG. 3 is a view showing a main part of a cement production facility having a calciner. In this figure, reference numeral 13 denotes a calciner.
The calciner 13 is disposed between the second cyclone 3b from the bottom and the cyclone 3a at the lowermost position. The calciner 13 is supplied with the raw material from the cyclone 3b and heats the raw material to form the cyclone 3a. To be supplied.
The calciner 13 is supplied with the exhaust gas of the rotary kiln 5 from the lower end thereof, is supplied with the cooler bleed air D, and is heated by a burner 61 provided at the lower end. Cooler bleed air D is high-temperature air used for cooling the cement clinker in the cooler 7. Reference numeral 71 denotes a hot air flow path for supplying the cooler bleed air D to the calciner 13.
[0038]
Then, the mixed and crushed material C is supplied to, for example, the upper end portion of the side of the calciner 13 and is heated in the calciner 13 in the same manner as the raw material supplied from the cyclone 3b. It is supplied to the rotary kiln 5 via 5B.
[0039]
Further, the calciner 13 may have the structure shown in FIG. That is, the calciner 13 shown in FIG. 4 has a substantially container-like shape as each of the cyclones 3a, 3b, 3c, and 3d, and receives supply of air from the fluidizing fan 131 from a lower end thereof. The cooler bleed air D is supplied and heated by a burner 61 provided at the lower end.
Then, the mixed and crushed material C is supplied to, for example, the upper end portion of the side of the calciner 13, heated in the calciner 13, and supplied to the cyclone 3 a together with the combustion gas and the gas such as the cooler bleed air D. From 3a, it is supplied to the rotary kiln 5 via the kiln bottom 5B.
[0040]
Further, even when dioxins are contained as an organic substance, the rotary kiln in the cement firing step has a considerably higher temperature than the decomposition temperature of dioxin, and therefore can be sufficiently decomposed.
[0041]
That is, examples of the contaminated soil containing dioxins include soil and sludge contaminated with dioxins around waste incineration plants, other incineration plants, and around landfills. Contaminated soil containing dioxins includes debris, brick debris, and concrete lumps generated when dismantling facilities that generate so-called dioxins, such as refuse incineration facilities and other incineration facilities. It may be. Furthermore, the contaminated soil containing dioxins may be waste such as building interior materials that may generate dioxins by combustion, ie, organic chlorine-based waste.
[0042]
Soil, sludge, debris, bricks, concrete lumps, etc. contaminated with dioxins, building interior materials, etc., around the refuse incineration plant, etc., are pulverized by the wet mill 11 together with the solvent B as described above. Then, a slurry-like mixed and crushed product C is formed, and the mixed and crushed product C is fed into the kiln tail portion 5B of the rotary kiln 5, the calciner 13, and the high-temperature portion of the preheater 3, for example, the cyclone 3a by the slurry pump 12. Will be. However, debris, bricks, concrete lumps and the like having a large particle size may be introduced into the wet mill 11 after being crushed by a crusher.
[0043]
In addition, dioxins refer to 2,3,7,8-tetrachlorodibenzo-p-dioxin and its analogous compounds, and polychlorodibenzo-having dibenzo-p-dioxin nucleus substituted with 1 to 8 chlorine atoms. p-dioxins (PCDDs) and polychlorodibenzofurans (PCDFs) in which 1 to 8 chlorine atoms have been substituted on the dibenzofuran nucleus.
The dioxins can be decomposed by staying in a high-temperature atmosphere of 800 ° C. or more for 2 seconds or more.
[0044]
Therefore, the inside of the kiln bottom 5B at 800 to 1100 ° C., the inside of the calciner 13 at 800 to 900 ° C., and the lowermost cyclone 3a at 800 to 900 ° C. without the calciner 13 When charged, the dioxins can be surely decomposed into harmless ones after 2 seconds or more after the charging. In addition, the dioxins do not remain in the cement clinker since they always pass through the atmosphere of 1450 ° C. during the production of the cement clinker in the rotary kiln 5 over several tens of minutes.
[0045]
In addition, when the thing containing dioxins is introduced into the preheater 3, if the equipment does not have the calciner 13, the temperature between the kiln bottom 5B, which is the highest temperature, and the cyclone 3a at the lowest position as described above, Alternatively, it is preferable to put the mixed and crushed material C into the cyclone 3a at the lowermost position. However, as long as the temperature is 800 ° C. or more , it may be introduced into other cyclones 3b, 3c, 3d, etc., or a flow path connecting these. Further, even in the case where the calciner 13 is provided, the mixed and crushed material C may be charged into the cyclone 3a or the like at the lowest position. Further, it may be charged into both the calciner 13 and the cyclone 3a or the like, or may be charged into all of the calciner 13, the cyclone 3a and the kiln tail 5B. Incidentally, when there is the calciner 13 shown in FIGS. 3 and 4, the temperature in the cyclone 3a is 800 to 900 ° C., so that the dioxins can be decomposed more effectively in the cyclone 3a.
[0046]
【The invention's effect】
As described above, according to the first aspect of the present invention, a solvent for imparting fluidity is added to the organic substance-contaminated soil and ground by a wet mill, and then the cement-fired soil is heated in a high-temperature atmosphere of 800 ° C. or higher. Since the cement clinker is manufactured in the process, the organic matter component of the soil contaminated with organic matter can be consumed as a part of the fuel, and the soil can be used as a part of the cement raw material (a part of the clay). As a cement clinker. Therefore, it is possible to dispose the organic matter-contaminated soil while making effective use of it, and to save the clay content as a cement raw material and the fuel for firing.
[0047]
Further, since the organic-contaminated soil is mixed and pulverized with a solvent in a wet mill, the rek (e.g., stone) contained in the soil can be finely pulverized, and the quality of the cement clinker is not adversely affected.
[0048]
According to the second aspect of the present invention, the point of introduction of the pulverized organic matter-contaminated soil is at least in the kiln bottom of the rotary kiln, the calciner provided in front of the rotary kiln, and the high-temperature part of the preheater located in front of the rotary kiln. Since it is located anywhere, the contained organic component can be reliably burned.
[0049]
According to the third aspect of the present invention, since at least one of waste oil, waste liquid, sludge, water, and a fluidizing agent is used as the solvent, pulverization and mixing with a wet mill can be performed smoothly and reliably. . In particular, when waste oil, waste liquid, or sludge is used as a solvent, the organic components can be used as fuel, which can contribute to savings in fuel costs and enable effective disposal of such waste. Become.
[0050]
According to the invention of claim 4, since at least one of calcium carbonate, slaked lime, quicklime and lime-based waste is mixed in addition to the solvent, it is possible to effectively utilize them and save cement raw materials. Can be. In addition, since these contaminants become cement components, even when a large amount of organic matter-contaminated soil is introduced, the composition of the cement clinker can be adjusted to an appropriate range, so that the composition of the cement clinker is not affected. Can be
[0051]
According to the fifth aspect of the present invention, the dioxins are always heated to the decomposition temperature or higher by introducing the dioxins into the cement firing step.
Accordingly, soil contaminated with organic matter containing dioxins can be effectively used as cement, and the environment can be improved by decomposing dioxins into harmless ones.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a cement production facility for performing a treatment method of the present invention.
FIG. 2 is a schematic configuration diagram showing a main part of the cement production facility without a calciner.
FIG. 3 is a schematic configuration diagram showing a main part of the cement production facility, which has a calciner;
FIG. 4 is a schematic configuration diagram showing a main part of the cement production facility having another calcining furnace.
[Explanation of symbols]
A soil contaminated with organic matter B solvent C mixed and crushed material (crushed material)
G Cement raw material 3 Preheater 3a Lowermost cyclone (high temperature part of preheater)
5 rotary kiln 5B kiln bottom 11 wet mill 13 calciner

Claims (5)

When the cement raw material is pulverized by a dry mill and preheated by a preheater, the cement raw material is put into a rotary kiln for calcining cement to produce a cement clinker.
After adding a solvent for imparting fluidity to the organic contaminated soil and pulverizing it with a wet mill, the mixture is put into a cement burning step under a high-temperature atmosphere of 800 ° C. or more, and the organic components of the organic contaminated soil are converted into fuel. A method for treating organic matter-contaminated soil, comprising consuming the organic matter-contaminated soil as part of a cement raw material while disposing the organic matter-contaminated soil. The charging point of the pulverized material of the organic contaminated soil, the kiln tail of the rotary kiln, a calciner provided in the previous stage of the rotary kiln, at least one of the high-temperature portion of the preheater located in the previous stage of the rotary kiln, The method for treating an organic matter-contaminated soil according to claim 1. The method according to claim 1, wherein at least one of waste oil, waste liquid, sludge, water, and a fluidizing agent is used as the solvent. The method according to any one of claims 1 to 3, wherein at least one of calcium carbonate, slaked lime, quicklime, and lime-based waste is mixed in addition to the solvent. The method for treating organic matter-contaminated soil according to any one of claims 1 to 4, wherein the organic matter-contaminated soil includes soil contaminated with dioxins as organic matter.

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