JP4009883B2 - Method and apparatus for separating and removing harmful substances - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for separating and removing various harmful substances such as cyan and arsenic contained in contaminated soil and industrial waste from the contaminated soil.
[0002]
[Prior art]
When foundation works are carried out at a factory site, substances such as cyan and arsenic may be carried in excavated soil. If such excavated soil is left as it is, cyanide and the like may diffuse into the environment via groundwater and the like, which may have a significant impact on the ecosystem.
[0003]
For this reason, such substances are treated as hazardous substances that should be closely monitored for diffusion to the environment together with mercury, cadmium, organic neighbors, lead, hexavalent chromium, PCB, etc., and are controlled or blocked separately from general waste. Various measures must be taken, such as disposal at a type waste disposal site, insolubilization with a predetermined chemical, and recovery by energization.
[0004]
[Problems to be solved by the invention]
However, recently, it has become quite difficult to secure a waste disposal site from the viewpoint of environmental protection, and there has been a problem that there is no disposal site to be disposed of.
[0005]
On the other hand, insolubilization treatment, the treated soil may become a new industrial waste. In that case, as described above, a problem arises in terms of securing a disposal site. An energization period is required, and if it is an electrically neutral harmful substance, it is difficult to recover in the first place. In any case, a method for efficiently separating and removing harmful substances such as cyan and arsenic from contaminated soil has not yet been established.
[0006]
The present invention has been made in view of the above-described circumstances, and provides a method and apparatus for separating and removing harmful substances capable of efficiently separating and removing harmful substances such as cyan and arsenic from contaminated soil and the like. With the goal.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the method for separating and removing harmful substances according to the present invention, the object containing the harmful substances is sealed in an airtight space and predetermined vaporization promotion is performed on the object. And then volatilizing the harmful substance from within the object by lowering the atmospheric pressure in the hermetic space to cause a boiling point drop of the harmful substance, and removing the volatilized harmful substance from the outside of the hermetic space. In this method, the harmful substance is cyan and the vaporization accelerator is an acidic solution, or the harmful substance is arsenic and the vaporization accelerator is an acidic solution and an oxidizing agent.
[0008]
In addition, the hazardous substance separation / removal device according to the present invention is connected to an airtight container in which an object containing a hazardous substance is accommodated and an airtight space in the container, as described in claim 2. A storage tank in which a predetermined vaporization accelerator is stored; an exhaust pipe communicated with an airtight space in the container; a vacuum pump that draws out gas in the container through the exhaust pipe and lowers the atmospheric pressure; A collecting device connected to an upstream side or a downstream side of a vacuum pump for collecting harmful substances discharged from the container, wherein the vacuum pump is the vaporization accelerator by lowering the boiling point of the harmful substances due to a decrease in atmospheric pressure. A device for separating and removing harmful substances, which volatilizes the harmful substances from the object to which is added, and discharges the volatilized harmful substances to the outside of the container, wherein the harmful substances are cyan. Accelerator is of the acid solution, or toxic substances vaporized accelerator arsenic is an acidic solution and oxidizing agent.
[0009]
Moreover, the harmful substance separation / removal device according to the present invention is such that the container is formed of a rigid container.
[0010]
Moreover, the harmful substance separation / removal device according to the present invention is configured such that the container is configured by a sheet, and the sheet is configured to be sealed in a bag shape in a state where the object is stored.
[0011]
In the method for separating and removing toxic substances according to the present invention, the object containing the toxic substances is sealed in the airtight space, and a vaporization accelerator is added to the object. Lower. In this manner, in the airtight space, the harmful substance is easily vaporized by the action of the vaporization accelerator, and the boiling point of the harmful substance is lowered due to the decrease in air pressure. Therefore, the harmful substance is volatilized from within the object. Therefore, by discharging this to the outside of the airtight space, harmful substances contained in the object are separated and removed. Even after the air is removed, the gas in the airtight space, that is, the volatilized harmful substance is removed and the reduced pressure state is maintained, so that the harmful substance in the object is continuously volatilized.
[0012]
Objects that contain toxic substances are mainly contaminated soil, but slag, incinerated ash, sludge, concrete waste, plastic waste, waste wood, etc. are also included.
[0013]
The harmful substance in the present invention is an acidic solution among substances whose vaporization is promoted under a reduced pressure, particularly in a state of almost vacuum of several mmHg or less, by adding a vaporization accelerator, even if the pressure is reduced, but does not vaporize at room temperature. Cyanide that volatilizes as a cyanide gas by adding, or arsenic that volatilizes as an arsine gas by adding an acidic solution and adding an oxidizing agent to increase the oxidation-reduction potential. Here, in the case of cyan, an acidic solution is a vaporization accelerator, and in the case of arsenic, an acidic solution and an oxidizing agent are vaporization accelerators.
[0015]
How to form the airtight space is arbitrary. For example, the internal space of the airtight container may be an airtight space, and an object such as excavated earth and sand may be put into the airtight container. If the soil is actually contaminated, the underground wall may be formed so as to surround the contaminated area, and the airtight space may be formed by covering the upper part with an airtight sheet.
[0016]
The air pressure in the airtight space is desirably set to be equal to or lower than the vapor pressure of the harmful substance at the temperature in the space with the vaporization accelerator added. If the atmospheric pressure is lowered to this level, harmful substances contained in the object volatilize immediately in combination with the action of the vaporization accelerator. It is not always necessary to lower the vapor pressure of the harmful substance described above, and although the efficiency is slightly reduced, a considerable volatilization effect can be expected if the pressure is close to the vapor pressure.
[0017]
In the hazardous substance separation / removal device according to the present invention, first, an object containing the harmful substance is charged and sealed in an airtight container, and a vaporization accelerator stored in a storage tank is sent into the container. Add in the object. Next, the air in the container is evacuated by a vacuum pump through the exhaust pipe, and the air pressure is lowered.
[0018]
In this manner, in the airtight space, the harmful substance is easily vaporized by the action of the vaporization accelerator, and the boiling point of the harmful substance is lowered due to the decrease in air pressure. Therefore, the harmful substance is volatilized from within the object. Therefore, this is discharged to the outside of the airtight space and further collected by a collecting device. Even after the air is removed, the gas in the airtight space, that is, the volatilized harmful substance is removed and the reduced pressure state is maintained, so that the harmful substance in the object is continuously volatilized.
[0019]
The explanation regarding the harmful substance, the object containing it, and the atmospheric pressure is the same as described above, and is omitted here.
[0020]
As an airtight container, any structure that can withstand the atmospheric pressure from the outside can be used as long as the internal vacuum state can be substantially maintained. If there is a concern that the volatilization of harmful substances from the object will be hindered, if the container is configured with a rigid container, atmospheric pressure will not act on the object. Volatilizes smoothly.
[0021]
On the other hand, if there is no risk that volatilization of harmful substances will be prevented even if atmospheric pressure acts on the object, for example, if the object is contaminated soil containing a lot of gravel and gravel, the container is covered with a sheet. If configured, and the sheet is configured to be sealed in a bag shape in a state in which the object is accommodated, a pressurizing action is added to the volatilizing action according to the present invention, and more efficient separation and removal are possible. In addition, since the container is a sheet, the effect of being able to be folded during storage and transportation is also obtained.
[0022]
In addition, when using the airtight sheet, after expanding it and placing the object, it is sealed in a bag shape so as to wrap the object, and then the air inside the container is drawn out as described above and harmful substances May be removed by volatilization. The airtight sheet can be arbitrarily selected from materials such as nylon, vinylon, and polyester tarpaulin.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a method and apparatus for separating and removing harmful substances according to the present invention will be described below with reference to the accompanying drawings.
[0024]
FIG. 1 is an overall perspective view showing a hazardous substance separation and removal apparatus according to this embodiment. As can be seen in the figure, the hazardous substance separation / removal device 1 according to the present embodiment includes an airtight container 3 in which contaminated soil 2 as an object containing cyan, which is a harmful substance, is accommodated, and the accommodation. A storage tank 5 that is connected to an airtight space in the body through a supply pipe 17 and stores an acidic solution that is a vaporization accelerator, an exhaust pipe 4 that is disposed through the container 3, and gas-liquid separation in the exhaust pipe It consists of a vacuum pump 7 connected via a tank 6 and a collecting device 8 connected downstream of the vacuum pump. The vacuum pump 7 changed from cyan in the container 3 by the addition of an acidic solution. Hydrocyanic acid is volatilized as a hydrocyanic acid gas by lowering the atmospheric pressure by pulling out the gas in the container through the exhaust pipe 4 and lowering the atmospheric pressure in the container 3, and further containing the volatilized hydrocyanic acid gas Drain outside the body 3 It has become the jar.
[0025]
The airtight container 3 is formed by wrapping an airtight sheet 11 formed of a material such as nylon, vinylon, polyester tarpaulin or the like in a bag shape in a state of containing contaminated soil 2 as will be described later, followed by adhesion, welding, or the like. It is good to seal and constitute by this method.
[0026]
The exhaust pipe 4 can be made of, for example, hard vinyl chloride, and the tip portion where a large number of holes 16 are formed is embedded in a sand mat 9 installed at the bottom of the container 3. The air inside the container 3 that has passed through the mat and the hydrocyanic acid gas from the contaminated soil 2 are sucked from the holes 16.
[0027]
That is, the sand mat 9 serves as a so-called vent for smoothly discharging air and hydrocyanic acid gas without clogging the holes 16 with the contaminated soil 2, and is contained in the weight of the contaminated soil 2 and the soil. It also serves as a protective layer that prevents the airtight sheet 11 from being broken by protrusions such as gravel.
[0028]
The gas-liquid separation tank 6 is provided with a barometer 10 so that the pressure inside the communicating container 3 can be measured. A drain cock 12 is provided near the bottom of the tank, and a valve 13 is provided. By opening the cock in a closed state, the water evaporated from the contaminated soil 2 and accumulated in the gas-liquid separation tank 6 can be drained. In addition, when the hydrocyanic acid gas volatilized from the contaminated soil 2 is dissolved in such water, the water is extracted while being maintained in an airtight state.
[0029]
The collection device 8 is a device for collecting and recovering hydrocyanic acid gas, which is a harmful substance, from the gas discharged from the vacuum pump 7, and the inside thereof is filled with activated carbon for adsorbing the hydrocyanic acid gas. . Although a small amount of hydrocyanic acid gas may be released from the exhaust port to the atmosphere without being adsorbed in the collection device 8, in such a case, the exhaust port of the collection device 8 is connected to a heating combustion furnace. In the combustion furnace, it is preferable to burn the hydrocyanic acid gas and decompose it into nitrogen, carbon dioxide and water to make it non-toxic.
[0030]
In order to manufacture the harmful substance separation and removal apparatus 1 according to the present embodiment on site, first, as shown in FIG. 2 (a), an airtight sheet 11 is spread on the ground, and a sand mat 9 is placed thereon. In addition, the tip of the exhaust pipe 4 is embedded in the mat.
[0031]
Next, as shown in FIG. 4B, the contaminated soil 2 is piled on the sand mat 9, and the tip of the supply pipe 17 is embedded in the contaminated soil.
[0032]
Next, the edge of the airtight sheet 11 is lifted to wrap the sand mat 9 and the contaminated soil 2 in a bag shape. Then, the edges 3 are overlapped and bonded and sealed by a method such as welding or adhesion to form a container 3 having an airtight space formed therein as shown in FIG.
[0033]
Finally, the storage tank 5 is connected to the supply pipe 17, and the gas-liquid separation tank 6, the vacuum pump 7, and the collecting device 8 are sequentially connected to the exhaust pipe 4 as shown in FIG.
[0034]
In order to separate and remove cyan from the contaminated soil 2 using the separation and removal apparatus 1 assembled in this way, first, the acidic solution in the storage tank 5 is sent into the container 3 to adjust the pH of the contaminated soil 2. Reduce. In this way, cyan in the contaminated soil 2 changes to hydrocyanic acid in an acidic environment, and is easily vaporized as a cyanide gas.
[0035]
In this state, the vacuum pump 7 is operated to evacuate the air in the container 3 to lower the air pressure in the container. In order to lower the air pressure, it is desirable to operate the vacuum pump 7 so that the air pressure in the container 3 is lower than the vapor pressure of hydrocyanic acid at the temperature in the container. Here, assuming that the vapor pressure curve of hydrocyanic acid is approximately as shown in FIG. 3, when the temperature is 10 ° C., the atmospheric pressure in the container may be lowered to about 100 mmHg or less. Further, if it is further lowered to several mmHg, it is possible to efficiently volatilize even those in the state where they are present in the interior of the soil particles or in the fine voids between the soil particles and are not easily separated. In the figure, the vapor pressure curves of kerosene, water, and ethyl alcohol are also shown for reference.
[0036]
When the air pressure in the container 3 is lowered in this way, the boiling point of hydrocyanic acid drops due to the decrease in air pressure in the container, and hydrocyanic acid in the contaminated soil 2 immediately volatilizes as hydrocyanic acid gas. 7 is sucked from the container 3 and sent to the collecting device 8, and the cyanating gas is adsorbed and collected by the collecting device.
[0037]
Even after the air is removed, the cyanide in the contaminated soil 2 is continuously volatilized by removing the gas in the airtight space, that is, the volatilized cyanate gas, and maintaining the reduced pressure state.
[0038]
The time for operating the vacuum pump 7 is appropriately adjusted depending on how much cyan is desired to be removed. Once the air pressure is lowered to a predetermined level, it is sufficient to operate the vacuum pump 7 intermittently or with reduced output so that the pressure is reduced by the pressure increase due to the hydrocyanic acid gas volatilized in the container 3. .
[0039]
When the cyan in the contaminated soil 2 is separated and removed to a desired degree, the vacuum pump 7 is stopped, the airtight sheet 11 is opened, and the treated soil is taken out from the sheet. The treated soil may be used as an embankment material, for example.
[0040]
As described above, according to the method and apparatus for separating and removing harmful substances according to the present embodiment, cyanide is easily changed to hydrocyanic acid by the addition of an acidic solution, and in this state, hydrocyanic acid is reduced by reducing the atmospheric pressure. By lowering the boiling point of, cyanide can be immediately volatilized from the contaminated soil 2 as cyanuric acid gas and discharged to the outside of the container 3.
[0041]
This makes it possible to efficiently separate and remove extremely toxic cyan from the contaminated soil, eliminating the need for a waste disposal site for disposing of the contaminated soil. Moreover, unlike the water washing which requires dehydration after the treatment, the treated soil can be reused immediately.
[0042]
Further, since the vacuum pump 7 is operated so that the atmospheric pressure in the container 3 is equal to or lower than the vapor pressure of hydrocyanic acid at the temperature in the container, cyan contained in the contaminated soil 2 is in the form of cyanide gas. It can be volatilized immediately and the cyan content in the contaminated soil can be reduced in a short time.
[0043]
Further, since the container 3 is composed of the airtight sheet 11, the atmospheric pressure acts on the contaminated soil 2 through the sheet. Therefore, the cyanide contained in the contaminated soil 2 is added to the volatilization action caused by the vaporization accelerator and the reduced pressure, and the pressurization action due to the atmospheric pressure is added, the discharge to the outside of the container 3 is promoted, and more efficient separation and removal is possible It becomes. Moreover, since the container 3 is the sheet | seat 11, the effect that it can be folded in the case of storage or conveyance is also acquired.
[0044]
Moreover, since the sand mat 9 as a protective layer is provided at the bottom of the container 3, even if the weight of the contaminated soil 2 is large or the contaminated soil includes protrusions, the container 3 is There is no damage. Therefore, the container 3 can be diverted.
[0045]
Further, since the exhaust pipe 4 is embedded in the sand mat 9, there is no possibility that the holes 16 formed in the pipe are blocked with the contaminated soil 2 to prevent the discharge of air and cyan, and the contaminated soil. Cyan can be volatilized from a wide range of 2.
[0046]
In the present embodiment, the object for separating and removing harmful substances is contaminated soil, but the object of the present invention is not limited to such contaminated soil, in addition to contaminated soil, slag, incinerated ash, sludge, Concrete waste, plastic waste, waste wood, etc. may be the target.
[0047]
In the present embodiment, the harmful substance is cyan. However, the harmful substance referred to in the present invention is not limited to such a substance, and can be applied to, for example, arsenic. In such a configuration, if an acidic solution and an oxidizing agent are added as a vaporization accelerator to an object such as contaminated soil containing arsenic, arsenic is easily vaporized in the form of arsine gas. If the air pressure in the hermetic space is lowered in the same manner as described above, arsenic can be volatilized and removed from the object. Further, mercury can be easily evaporated by adding hydrochloric acid to contaminated soil containing mercury.
[0048]
Moreover, in this embodiment, although the vaporization promoter is sent into the container, it may be added to and mixed with the contaminated soil in advance before sealing the container.
[0049]
Further, in the present embodiment, a substance that does not vaporize at room temperature even under reduced pressure but is accelerated by adding a vaporization accelerator is targeted, but may be volatilized under reduced pressure without using a vaporization accelerator. The present invention can also be applied to possible harmful substances. According to such a configuration, since the vaporization of harmful substances is accelerated, the separation and removal efficiency is remarkably improved.
[0050]
Further, in this embodiment, the container 3 is configured using the airtight sheet 11, but instead of such a configuration, as shown in FIG. 4A, a container 21 made of, for example, steel, having high rigidity is accommodated. The inside of the container 21 is an airtight space for containing the contaminated soil 2, and the gas-liquid separation tank 6, the vacuum pump 7 and the collection device similar to those shown in FIG. You may make it connect the apparatus 8 sequentially.
[0051]
According to such a configuration, when it is feared that volatilization of the harmful substance is hindered when atmospheric pressure acts on the contaminated soil 2 as the target object, the harmful substance can be volatilized smoothly from within the target object. . In this case, a perforated exhaust pipe 23 may be used as shown in FIG.
[0052]
In the present embodiment, the airtight space is formed using the container 3. However, if the actually contaminated ground is an object, the contaminated area in the ground 31 is shown in FIG. An underground wall 33 is formed so as to surround 32, and an upper part thereof is covered with an airtight sheet or a rigid plate 34 to form an airtight space, and an exhaust pipe 35 is passed through the underground wall 33, so that the gas-liquid separation tank 6 The vacuum pump 7 and the collecting device 8 may be sequentially connected. In addition, about the lower end of the underground wall 33, an airtight process is performed suitably as needed.
[0053]
In this embodiment, the gas-liquid separation tank 6, the vacuum pump 7, and the collecting device 8 are connected to the container 3 in this order. First, the gas-liquid separation tank may be a so-called dry type vacuum pump. For example, this may be omitted, and the order of the vacuum pump and the collection device may be changed.
[0054]
In the present embodiment, a sand mat is used as the protective layer, but instead, a plywood may be placed on the airtight sheet to form the protective layer, or may be made of asphalt or concrete. On the other hand, if the airtight sheet itself is given strength, or if there is no risk of damage due to the weight of the object, the protective layer may be omitted.
[0055]
Further, in the present embodiment, the sand mat 9 is adopted as a ventilation body. However, such a ventilation body can be any type as long as a passage for air or hydrocyanic acid gas is secured inside even if a constant overpressure is applied. For example, instead of spreading sand and gravel, a three-dimensional mesh mat formed of a polymer material may be used. In addition, a perforated pipe made of hard vinyl chloride or the like may be embedded in the leveled sand or gravel to further improve the air permeability.
[0056]
In addition, such a ventilation body, for example, can discharge cyan from a wide range of the object by branching the tip of the exhaust pipe or the ventilation soil 2 contains a lot of gravel, gravel, etc. This may be omitted if it has high properties.
[0057]
【The invention's effect】
As described above, according to the method for separating and removing harmful substances of the present invention according to claim 1, it becomes possible to efficiently separate and remove harmful substances such as cyan from the object, and dispose of the object. Therefore, unlike the methods such as water washing, the treated soil can be reused immediately.
[0058]
Moreover, according to the hazardous substance separation / removal apparatus of the present invention according to claim 2, it becomes possible to efficiently separate and remove harmful substances such as cyan from the object, and waste for disposing of the object. There is no need to install a disposal site, and unlike the methods such as water washing, the treated soil can be reused immediately.
[0059]
Further, according to the hazardous substance separation and removal apparatus of the present invention according to claim 3, in addition to the effect of claim 2, there is a concern that the volatilization of harmful substances may be hindered when atmospheric pressure acts on the object. In this case, it is possible to smoothly volatilize harmful substances from the inside of the object.
[0060]
According to the harmful substance separation / removal device of the present invention according to claim 4, in addition to the effect of claim 2, the harmful substance has an atmospheric pressure in addition to the vaporization action by the vaporization accelerator and the volatilization action by the reduced pressure. Discharge to the outside of the container is promoted by the pressurizing action, and more efficient separation and removal are possible. Moreover, the effect that the container can be folded in the case of storage and conveyance is also acquired.
[0061]
[Brief description of the drawings]
FIG. 1 is an overall perspective view of a hazardous substance separation and removal apparatus according to an embodiment of the present invention.
FIG. 2 is a construction procedure diagram showing a procedure for producing a hazardous substance separation / removal device according to the present embodiment on site;
FIG. 3 is a graph illustrating the operation of the hazardous substance separation and removal apparatus and method according to the present embodiment.
FIG. 4 is a cross-sectional view showing a hazardous substance separation and removal apparatus according to a modification.
FIG. 5 is a sectional view showing a method for separating and removing harmful substances according to a modification.
[Explanation of symbols]
1 Separation and removal equipment for hazardous substances 2 Contaminated soil (object)
3 Container 4, 22, 23, 35 Exhaust pipe 7 Vacuum pump 8 Collection device 9 Sandmat (vent, protective layer)
11, 34 Airtight sheet 21 Steel container (container)
33 Underground wall (airtight space)

Claims (4)

  By sealing an object containing a toxic substance in an airtight space and adding a predetermined vaporization accelerator to the object, and then lowering the atmospheric pressure in the airtight space to cause a boiling point drop of the toxic substance A method for separating and removing a harmful substance that volatilizes the harmful substance from the object and discharges the volatilized harmful substance to the outside of the airtight space, wherein the harmful substance is cyan and the vaporization accelerator is an acidic solution or harmful A method for separating and removing harmful substances, wherein the substance is arsenic and the vaporization accelerator is an acidic solution and an oxidizing agent.   An airtight container that contains an object containing a harmful substance, a storage tank that is connected to an airtight space in the container and stores a predetermined vaporization accelerator, and an airtight space in the container. An exhaust pipe, a vacuum pump that draws out the gas in the container through the exhaust pipe and lowers the atmospheric pressure, and is connected to an upstream side or a downstream side of the vacuum pump to capture harmful substances discharged from the container. The vacuum pump is configured to volatilize the harmful substance and volatilize the harmful substance from the object to which the vaporization accelerator is added by lowering the boiling point of the harmful substance due to a decrease in atmospheric pressure. A device for separating and removing harmful substances to be discharged to the outside of the container, wherein the harmful substances are cyan and the vaporization accelerator is an acidic solution, or the harmful substances are arsenic and the vaporization accelerator is an acidic solution and an acid. Separation apparatus for removing harmful substances, which is a drug.   The separation / removal device according to claim 2, wherein the container is formed of a rigid container.   The separation / removal device according to claim 2, wherein the container is constituted by a sheet, and the sheet is configured to be sealed in a bag shape in a state where the object is accommodated.

Images