Mercury contaminated soil treatment process and mercury contaminated soil treatment system

Abstract

The application provides a mercury-contaminated soil treatment process and a mercury-contaminated soil treatment system. The mercury-contaminated soil treatment process comprises: treating the mercury-contaminated soil by using a thermal desorption heating process, so that mercury in the mercury-contaminated soil is thermally desorbed from the mercury-contaminated soil in a gaseous form and forms mercury vapor; cooling the mercury vapor, so that at least part of the mercury in the mercury vapor is converted from the gaseous form to a liquid form and forms liquid mercury; performing a sedimentation process on the liquid mercury, in which the liquid mercury is combined with suspended material to form a mercury suspension and is suspended in an upper layer of the liquid, and the mercury in the mercury suspension is recovered and treated. The technical scheme provided by the application can solve the technical problem of poor mercury removal effect of the mercury-contaminated soil treatment process in the prior art.

Description

Technical Field

[0001] This invention relates to the field of mercury contaminated soil treatment technology, and more specifically, to a mercury contaminated soil treatment process and system. Background Technology

[0002] Currently, pollutants in contaminated soil are mainly classified into two types using existing technologies: heavy metal pollution and organic pollution. Heavy metal contaminated soil can be treated through chemical leaching or solidification and stabilization technologies, while organic contaminated soil can be treated through chemical leaching, chemical oxidation, or thermal desorption. For mercury-contaminated soil, although it belongs to heavy metal pollution, mercury itself has a certain degree of volatility, making it suitable for treatment using thermal desorption. Thermal desorption treatment of mercury-contaminated soil mainly involves heating to desorb the mercury from the soil. The mercury vapor generated by heating enters the gas treatment stage, where the mercury is cooled or adsorbed, thereby achieving mercury removal.

[0003] However, in the existing thermal desorption treatment of mercury-contaminated soil, most processes involve cooling mercury and water vapor from a gaseous state to a liquid state. Since mercury is denser than water, the cooled mercury settles to the bottom of the water and mixes with the bottom sediment to form mercury-containing sediment. Even if this sediment is dewatered and returned to the thermal desorption process, it will still be enriched in the sediment. Generally, this sediment is disposed of as hazardous waste, thus failing to effectively remove mercury from the entire treatment system. Summary of the Invention

[0004] The main objective of this invention is to provide a mercury-contaminated soil treatment process and system to solve the technical problem of poor mercury removal efficiency in existing mercury-contaminated soil treatment processes.

[0005] To achieve the above objectives, according to one aspect of the present invention, a process for treating mercury-contaminated soil is provided, comprising:

[0006] The process of thermal desorption with additional heat is used to treat mercury-contaminated soil so that the mercury in the contaminated soil is thermally desorbed from the soil in gaseous form and forms mercury vapor.

[0007] The mercury vapor is cooled so that at least a portion of the mercury in the mercury vapor changes from a gaseous state to a liquid state and forms liquid mercury;

[0008] A sedimentation process is used to treat liquid mercury, in which liquid mercury combines with a suspending material to form a mercury suspension that is suspended on the upper layer of the liquid, and the mercury in the mercury suspension is then recovered.

[0009] Furthermore, the mercury in the mercury suspension is recovered through the following processes:

[0010] The mercury suspension is heated so that the mercury in the suspension evaporates as vapor.

[0011] The evaporated gaseous mercury is condensed to obtain mercury products.

[0012] Furthermore, after cooling the mercury vapor, a portion of it remains in a gaseous state to form non-condensable gases; the mercury contaminated soil treatment process also includes:

[0013] Mercury in non-condensable gas is adsorbed using a mercury-removing adsorbent, thereby reducing the mercury concentration in the non-condensable gas to a preset value.

[0014] After the mercury concentration in the non-condensable gas is reduced to a preset value, the non-condensable gas is introduced into the combustion chamber of the thermal deheating process for combustion and then discharged.

[0015] Furthermore, prior to using mercury-removing adsorbents to adsorb mercury from non-condensable gases, the mercury-contaminated soil treatment process also includes:

[0016] Non-condensable gases are subjected to gas-liquid separation to remove liquid from the non-condensable gases; and / or,

[0017] Dust removal is performed on the non-condensable gas to remove dust from it.

[0018] Furthermore, in the sedimentation process, sediment forms beneath the liquid; mercury-contaminated soil treatment processes also include:

[0019] The sediment was dewatered, and the mercury content of the dewatered sediment was tested.

[0020] When the mercury content of the dewatered sediment is less than the predetermined value, the dewatered sediment will be discharged.

[0021] When the mercury content of the dewatered sediment is greater than or equal to a predetermined value, a thermal dewatering process with additional heating is used to treat the dewatered sediment.

[0022] Furthermore, in the sedimentation process, sediment forms beneath the liquid. Mercury-contaminated soil treatment processes also include:

[0023] The water between the sediment and the mercury suspension is separated, and the separated water is cooled.

[0024] The mercury vapor is cooled by spraying it with cooled water.

[0025] Furthermore, the soil is treated using a thermal descaling and additional heating process, including: controlling the heating temperature in the thermal descaling and additional heating process to be T1, where 200℃≤T1≤500℃; controlling the heating temperature in the thermal descaling and additional heating process to be t, where 20min≤t≤60min; and / or,

[0026] Cooling mercury vapor includes: reducing the temperature of mercury vapor to T2, where 30℃≤T2≤50℃.

[0027] According to another aspect of the present invention, a mercury-contaminated soil treatment system is provided, applicable to the mercury-contaminated soil treatment process described above. The mercury-contaminated soil treatment system includes:

[0028] Thermal desorption structures are used for thermal desorption of mercury-contaminated soil by additional heat treatment to form mercury vapor.

[0029] The cooling structure has an air inlet, a liquid outlet, and a cooling chamber that is connected to both the air inlet and the liquid outlet. The air inlet is used to introduce mercury vapor, which is cooled in the cooling chamber to form liquid mercury.

[0030] The sedimentation separation structure has an inlet, an overflow, and a sedimentation chamber that is connected to both the inlet and the overflow. Suspended material is placed in the sedimentation chamber. The inlet is used to introduce liquid mercury so that the liquid mercury combines with the suspended material to form a mercury suspension. The overflow is used to discharge the mercury suspension.

[0031] The mercury recovery structure has a recovery inlet that is connected to an overflow outlet. The mercury suspension enters the mercury recovery structure through the recovery inlet.

[0032] Furthermore, the cooling structure also has an air outlet connected to a cooling chamber, which is used to discharge non-condensable gases from mercury vapor; the mercury contaminated soil treatment system also includes:

[0033] The non-condensable gas treatment structure includes a gas-liquid separation structure and a mist-catching structure. The gas-liquid separation structure is used to separate the non-condensable gas into gas and liquid, and the mist-catching structure is used to remove dust from the non-condensable gas.

[0034] The mercury adsorption structure is connected to the non-condensable gas treatment structure, so as to adsorb mercury onto the gas after it has been treated by the non-condensable gas treatment structure.

[0035] Furthermore, the sedimentation separation structure also includes a sludge discharge port, located at the bottom of the sedimentation chamber and connected to it, for discharging bottom sludge from the bottom of the sedimentation chamber; the cooling structure includes a spray system installed inside the cooling chamber, the liquid sprayed by the spray system being used to cool mercury vapor; the mercury contaminated soil treatment system also includes:

[0036] The heat exchange structure has a heat exchange inlet for introducing liquid between the mercury suspension and the bottom sediment, and a heat exchange outlet connected to the spray element.

[0037] By applying the technical solution of this invention, liquid mercury is combined with suspended materials to form a mercury suspension during the sedimentation process. The mercury in the mercury suspension is then recycled, which can improve the removal efficiency of mercury, effectively realize the resource recovery of mercury in the soil, and avoid producing a large amount of mercury-containing sediment. Attached Figure Description

[0038] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0039] Figure 1 A flow chart of a mercury-contaminated soil treatment process according to Embodiment 1 of the present invention is shown.

[0040] Figure 2 A schematic diagram of the structure of a mercury-contaminated soil treatment system according to Embodiment 2 of the present invention is shown;

[0041] Figure 3 A schematic diagram of the separation distance of the sedimentation separation structure provided according to Embodiment 2 of the present invention is shown.

[0042] The above figures include the following reference numerals:

[0043] 10. Thermal desorption structure; 20. Cooling structure; 30. Sedimentation separation structure; 40. Mercury recovery structure; 50. Non-condensable gas treatment structure; 60. Mercury adsorption structure; 70. Heat exchange structure; 80. Feeding device; 90. Discharge device; 100. Reagent preparation structure; 110. Dehydration structure. Detailed Implementation

[0044] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0045] like Figure 1 As shown, Embodiment 1 of the present invention provides a mercury-contaminated soil treatment process, which includes: treating the mercury-contaminated soil using a thermal desorption process to thermally desorb mercury from the soil in a gaseous form and form mercury vapor; cooling the mercury vapor to convert at least a portion of the mercury in the mercury vapor from a gaseous state to a liquid state and form liquid mercury; and performing a sedimentation process on the liquid mercury, in which the liquid mercury combines with a suspension material to form a mercury suspension and suspends in the upper layer of the liquid, and recovering the mercury in the mercury suspension.

[0046] The mercury-contaminated soil treatment process provided in this embodiment combines liquid mercury with suspended materials to form a mercury suspension during the sedimentation process. The mercury in this suspension is then further recovered, which significantly improves the mercury removal efficiency and effectively achieves the resource recovery of mercury from the soil without generating large amounts of mercury-containing sediment. Therefore, the mercury-contaminated soil treatment process provided in this embodiment can solve the technical problem of poor mercury removal efficiency in existing mercury-contaminated soil treatment processes.

[0047] It should be noted that the mercury vapor here may contain not only mercury, but also water vapor and dust. The suspending material can be a nanoscale sulfur-containing compound that can bind with the mercury, thereby causing the mercury to float to the surface of the water.

[0048] In this embodiment, the recovery of mercury from a mercury suspension includes: heating the mercury suspension to cause the mercury to evaporate as vapor; and condensing the evaporated gaseous mercury to obtain a mercury product. This method facilitates the effective recovery of mercury from the mercury suspension, thereby improving mercury removal.

[0049] Specifically, in the process of recovering mercury suspension, the suspended mercury particles can be circulated together with water. Mercury recovery is initiated when the concentration of mercury in the suspension reaches a certain level. Specifically, water is recycled throughout the thermal desorption process. Water is only replaced when the water quality deteriorates after a certain number of cycles. During this process, the suspended mercury particles participate in multiple cycles with the water. The mercury concentration gradually increases during this circulation process. Once a certain concentration is reached, the suspension recovery process can be initiated, thereby recovering the mercury and effectively improving the efficiency of mercury recovery operations.

[0050] Specifically, after cooling the mercury vapor, a portion of it remains in a gaseous state to form non-condensable gas. The mercury contaminated soil treatment process also includes using a mercury-removing adsorbent to adsorb mercury from the non-condensable gas, reducing the mercury concentration in the non-condensable gas to a preset value. This method facilitates the effective removal of mercury from the non-condensable gas, ensuring the treatment effect of mercury pollution. Specifically, the selected mercury-removing adsorbent is supported by an improved adsorption material to better enhance the adsorption effect on mercury in the gas.

[0051] In this embodiment, after the mercury concentration in the non-condensable gas is reduced to a preset value, the mercury-contaminated soil treatment process further includes: introducing the non-condensable gas into the combustion chamber of the thermal deheating process for combustion and then discharging it. This method facilitates effective treatment of the non-condensable gas before discharge, avoiding the environmental impact of direct discharge.

[0052] Specifically, before using a mercury-removing adsorbent to adsorb mercury from non-condensable gas, the mercury-contaminated soil treatment process also includes: gas-liquid separation of the non-condensable gas to remove liquid from it; and / or dust removal of the non-condensable gas to remove dust particles. This method effectively removes both liquid and dust from the non-condensable gas, improving its cleanliness and preventing other components in the gas from affecting the adsorption of mercury by the adsorbent, thus ensuring the adsorbent can effectively adsorb mercury from the non-condensable gas.

[0053] In this embodiment, during the sedimentation process, sediment is formed below the liquid. The mercury-contaminated soil treatment process further includes: dewatering the sediment and detecting the mercury content of the dewatered sediment; when the mercury content of the dewatered sediment is less than a predetermined value, the dewatered sediment is discharged; when the mercury content of the dewatered sediment is greater than or equal to the predetermined value, a thermal dewatering process with added heat is used to treat the dewatered sediment. This method facilitates further treatment of the sediment, avoids excessive mercury content in the sediment, and effectively ensures the mercury removal effect.

[0054] Specifically, in this embodiment, during the sedimentation process, sediment is formed below the liquid. The mercury-contaminated soil treatment process further includes: separating the water between the sediment and the mercury suspension, and cooling the separated water; then using the cooled water to spray and cool the mercury vapor. This method facilitates the effective recycling of water in the sediment and mercury suspension, facilitates spraying and cooling of mercury vapor, avoids water waste, and prevents the discharge of potentially mercury-containing water. Specifically, during the spraying process, the mercury vapor and water come into countercurrent contact to effectively cool the mercury vapor. During the cooling process, the mercury, dust, and water in the mercury vapor condense together and enter the sedimentation process.

[0055] In this embodiment, a thermal desulfurization and heating process is used to treat the soil, including: controlling the heating temperature in the thermal desulfurization and heating process to be T1, where 200℃≤T1≤500℃; and controlling the heating temperature in the thermal desulfurization and heating process to be t, where 20min≤t≤60min. This method facilitates the effective volatilization of mercury from mercury-contaminated soil in a gaseous form.

[0056] Specifically, cooling the mercury vapor includes lowering its temperature to T2, where 30°C ≤ T2 ≤ 50°C. This method facilitates the condensation of condensable substances within the mercury vapor. Preferably, the temperature of the mercury vapor can be lowered to 40°C.

[0057] like Figure 2 and Figure 3As shown, Embodiment 2 of the present invention provides a mercury-contaminated soil treatment system, applicable to the mercury-contaminated soil treatment process described above. The mercury-contaminated soil treatment system includes: a thermal desorption structure 10, a cooling structure 20, a sedimentation separation structure 30, and a mercury recovery structure 40. The thermal desorption structure 10 is used to perform thermal desorption and heat treatment on the mercury-contaminated soil to form mercury vapor. The cooling structure 20 has an air inlet, a liquid outlet, and a cooling chamber connected to both the air inlet and the liquid outlet. The air inlet is used to introduce mercury vapor, which is cooled in the cooling chamber to form liquid mercury. The sedimentation separation structure 30 has a liquid inlet, an overflow outlet, and a sedimentation chamber connected to both the liquid inlet and the overflow outlet. Suspended material is placed in the sedimentation chamber. The liquid inlet is used to introduce liquid mercury so that the liquid mercury combines with the suspended material to form a mercury suspension. The overflow outlet is used to discharge the mercury suspension. The mercury recovery structure 40 has a recovery inlet connected to the overflow outlet. The mercury suspension enters the mercury recovery structure 40 through the recovery inlet.

[0058] The mercury-contaminated soil treatment system provided in this embodiment can effectively treat mercury vapor and form a mercury-containing suspension during the sedimentation of liquid mercury. By using the mercury recovery structure 40 to recover the mercury in the mercury-containing suspension, the mercury in the mercury-contaminated soil can be effectively removed, thus solving the technical problem of poor mercury removal effect in the prior art.

[0059] Specifically, the sedimentation separation structure 30 primarily relies on the difference in specific gravity of the various materials to achieve separation. The residence time of liquid mercury in the sedimentation separation structure 30 can reach 40 to 60 minutes. The sedimentation separation structure 30 is equipped with inclined plates (or inclined tubes) and an overflow device to facilitate rapid material separation. The sedimentation chamber includes an interconnected sedimentation tank and an overflow tank, which are separated by a partition plate. The tops of the sedimentation tank and the overflow tank are connected, allowing the mercury suspension above the sedimentation tank to overflow into the overflow tank. The overflow outlet is connected to the overflow tank to facilitate the discharge of the mercury suspension from the overflow point.

[0060] Alternatively, the sedimentation separation structure 30 in this embodiment can also achieve sedimentation separation by means of hydrocyclones, centrifugation, etc.

[0061] The mercury recovery structure 40 includes a heating device and a condensation recovery device. The heating device can raise the temperature to 200°C to 500°C, and the condensation recovery device can lower the temperature to below 10°C, thereby maximizing the recovery of mercury through heating and condensation and realizing resource utilization.

[0062] In this embodiment, the cooling structure 20 also has an outlet connected to the cooling chamber, which is used to discharge non-condensable gases from the mercury vapor. The mercury-contaminated soil treatment system further includes a non-condensable gas treatment structure 50 and a mercury adsorption structure 60. The non-condensable gas treatment structure 50 includes a gas-liquid separation structure and a mist-catching structure. The gas-liquid separation structure is used to separate the non-condensable gases into gas and liquid components, and the mist-catching structure is used to remove dust from the non-condensable gases. The mercury adsorption structure 60 is connected to the non-condensable gas treatment structure 50 to adsorb mercury from the gas treated by the non-condensable gas treatment structure 50. This structural arrangement facilitates the effective removal of dust and moisture from the mercury vapor, and facilitates subsequent adsorption of mercury from the gas.

[0063] Specifically, in this embodiment, the air outlet is located above the cooling structure 20. The non-condensable gas treatment structure 50 in this embodiment includes a gas-liquid separation device and a mist-collecting device. Both the gas-liquid separation device and the mist-collecting device can be configured as multi-stage devices to enhance the treatment effect.

[0064] The mercury adsorption structure 60 in this embodiment includes a mercury adsorption shell and a mercury adsorbent. The mercury adsorbent fills the mercury adsorption shell and is made of an adsorbent material containing precious metals such as sulfur or silver. It can deeply adsorb mercury in the gas to ensure compliance with standards. Specifically, the mercury adsorption structure 60 in this embodiment can be configured as a standby unit, and the switching of the mercury adsorption structure 60 can be performed remotely to ensure continuous operation of the device.

[0065] Specifically, the sedimentation separation structure 30 in this embodiment also includes a sludge discharge port, which is located at the bottom of the sedimentation chamber and communicates with it. The sludge discharge port is used to discharge the bottom sludge located at the bottom of the sedimentation chamber. The cooling structure 20 includes a spray element installed in the cooling chamber. The liquid sprayed by the spray element is used to cool the mercury vapor. The mercury contaminated soil treatment system also includes a heat exchange structure 70. The heat exchange inlet of the heat exchange structure 70 is used to introduce the liquid located between the mercury suspension and the bottom sludge, and the heat exchange outlet of the heat exchange structure 70 is communicated with the spray element. With this structural arrangement, it is easy to recycle the liquid between the mercury suspension and the bottom sludge, which can avoid water waste and pollution problems caused by direct discharge.

[0066] The mercury-contaminated soil treatment system in this embodiment also includes a dewatering device, which can be a filter press or a centrifuge, etc.

[0067] In this embodiment, the process flow of the mercury-contaminated soil treatment system is as follows:

[0068] The contaminated soil first enters the thermal desorption structure 10 through the feeding device 80, which includes a feeding hopper, a feeding belt, and a belt scale. The thermal desorption structure 10 is primarily an indirect heating device; after entering, the flame and the mercury-contaminated soil do not directly contact each other. The mercury-contaminated soil is indirectly heated to a certain temperature (200–500℃), causing the mercury in the soil to volatilize as a gas. The heating residence time is 20–60 minutes to ensure sufficient volatilization of the mercury in the contaminated soil. The soil after mercury removal, as clean soil, is discharged through the discharge device 90, and the volatilized mercury vapor enters the cooling structure 20. In the cooling structure 20, the mercury vapor comes into contact with spray water, and the mercury changes from a gaseous state to a liquid state, entering the sedimentation and separation structure 30. A small amount of uncondensed mercury vapor enters the non-condensable gas treatment structure 50. The non-condensable gas treatment structure 50 mainly includes gas-liquid separation equipment and mist eliminator equipment to remove mercury vapor. After removing liquids and dust from the gas, the vapor treated by the non-condensable gas treatment structure 50 enters the mercury adsorption structure 60. In the mercury adsorption structure 60, a special mercury-removing adsorbent adsorbs the residual mercury in the gas, ensuring that the mercury concentration in the gas meets relevant standards. The treated gas is then returned to the combustion chamber of the thermal desorption structure 10 for combustion and discharge. The cooled liquid mercury enters the sedimentation separation structure 30, where solids in the liquid settle to form bottom sediment. The mercury combines with the suspended material and can remain suspended above the water surface. It enters a special mercury suspension collection tank through the overflow device in the sedimentation separation equipment. The separated mercury suspension enters the mercury recovery structure 40. In the mercury recovery structure 40, the mercury is recovered by heating, realizing the resource recovery of mercury. The sediment separated by sedimentation separation structure 30 has a relatively low mercury content. This portion of the sediment enters dewatering structure 110 for dewatering treatment. The dewatered sediment can be further treated by thermal desorption or directly discharged, depending on the mercury concentration. The water separated by sedimentation separation structure 30 is cooled by circulating water heat exchange structure 70 and then reused for spray cooling, achieving water recycling. The suspended material needs to be prepared by reagent preparation structure 100. The prepared suspended material can be directly added to the circulating water and introduced into the entire treatment system.

[0069] As can be seen from the above description, the above embodiments of the present invention achieve the following technical effects: based on the resource recovery of mercury in the soil, mercury is efficiently removed from the soil system, avoiding the generation of a large amount of mercury-containing sediment, thereby achieving the remediation of mercury-contaminated soil.

[0070] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0071] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0072] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0073] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0074] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this application.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for treating mercury-contaminated soil, characterized in that, include: A thermal desorption process with added heat is used to treat mercury-contaminated soil so that the mercury in the mercury-contaminated soil is thermally desorbed from the mercury-contaminated soil in gaseous form and forms mercury vapor; The mercury vapor is cooled so that at least a portion of the mercury in the mercury vapor changes from a gaseous state to a liquid state and forms liquid mercury; The liquid mercury is subjected to a sedimentation process in which the liquid mercury combines with a suspending material to form a mercury suspension that is suspended on the upper layer of the liquid, and the mercury in the mercury suspension is recovered.

2. The mercury-contaminated soil treatment process according to claim 1, characterized in that, The mercury recovery process from the mercury suspension includes: The mercury suspension is heated so that the mercury in the mercury suspension evaporates in the form of vapor; The evaporated gaseous mercury is condensed to obtain mercury products.

3. The mercury-contaminated soil treatment process according to claim 1, characterized in that, After the mercury vapor is cooled, A portion of the mercury vapor remains in a gaseous state to form non-condensable gas; the mercury-contaminated soil treatment process further includes: Mercury in the non-condensable gas is adsorbed using a mercury-removing adsorbent, thereby reducing the mercury concentration in the non-condensable gas to a preset value. After the mercury concentration in the non-condensable gas is reduced to a preset value, the non-condensable gas is introduced into the combustion chamber of the thermal deheating process for combustion and then discharged.

4. The mercury-contaminated soil treatment process according to claim 3, characterized in that, Before using a mercury-removing adsorbent to adsorb mercury from the non-condensable gas, the mercury-contaminated soil treatment process further includes: The noncondensable gas is subjected to gas-liquid separation to remove the liquid from the noncondensable gas; and / or, The non-condensable gas is subjected to dust removal to remove dust from the non-condensable gas.

5. The mercury-contaminated soil treatment process according to claim 1, characterized in that, In the sedimentation process, bottom mud is formed below the liquid; The mercury-contaminated soil treatment process also includes: The sediment was dewatered, and the mercury content of the dewatered sediment was tested. When the mercury content of the dehydrated sediment is less than a predetermined value, the dehydrated sediment is discharged. When the mercury content of the dewatered sediment is greater than or equal to the predetermined value, the dewatered sediment is treated using the thermal dewatering and additional heating process.

6. The mercury-contaminated soil treatment process according to claim 1, characterized in that, In the sedimentation process, sediment is formed below the liquid. The mercury-contaminated soil treatment process further includes: The water between the sediment and the mercury suspension is separated, and the separated water is cooled. The mercury vapor is cooled by spraying it with cooled water.

7. The mercury-contaminated soil treatment process according to claim 1, characterized in that, The soil treatment using a thermal descaling and additional heating process includes: controlling the heating temperature in the thermal descaling and additional heating process to be T1, where 200℃≤T1≤500℃; controlling the heating temperature in the thermal descaling and additional heating process to be t, where 20min≤t≤60min; and / or, Cooling the mercury vapor includes: cooling the mercury vapor to T2, where 30°C ≤ T2 ≤ 50°C.

8. A mercury-contaminated soil treatment system, characterized in that, The mercury-contaminated soil treatment process applicable to any one of claims 1 to 7, wherein the mercury-contaminated soil treatment system comprises: Thermal desorption structure (10) is used to perform thermal desorption on mercury-contaminated soil to form mercury vapor; Cooling structure (20) has an air inlet, a liquid outlet and a cooling cavity that is connected to both the air inlet and the liquid outlet. The air inlet is used to introduce the mercury vapor, and the mercury vapor is cooled in the cooling cavity to form liquid mercury. A sedimentation separation structure (30) has a liquid inlet, an overflow outlet, and a sedimentation chamber that is connected to both the liquid inlet and the overflow outlet. Suspended material is placed in the sedimentation chamber. The liquid inlet is used to introduce liquid mercury so that the liquid mercury combines with the suspended material to form a mercury suspension. The overflow outlet is used to discharge the mercury suspension. The mercury recovery structure (40) has a recovery inlet connected to the overflow port, and the mercury suspension enters the mercury recovery structure (40) through the recovery inlet.

9. The mercury-contaminated soil treatment system according to claim 8, characterized in that, The cooling structure (20) also has an air outlet, which is connected to the cooling chamber, which is used to discharge non-condensable gases from the mercury vapor; The mercury-contaminated soil treatment system also includes: The non-condensable gas treatment structure (50) includes a gas-liquid separation structure and a mist-catching structure. The gas-liquid separation structure is used to separate the non-condensable gas into gas and liquid, and the mist-catching structure is used to remove dust from the non-condensable gas. The mercury adsorption structure (60) is connected to the non-condensable gas treatment structure (50) to adsorb mercury onto the gas treated by the non-condensable gas treatment structure (50) through the mercury adsorption structure (60).

10. The mercury-contaminated soil treatment system according to claim 8, characterized in that, The settling separation structure (30) further includes a sludge discharge port, which is located at the bottom of the settling chamber and communicates with the settling chamber. The sludge discharge port is used to discharge the bottom sludge located at the bottom of the settling chamber. The cooling structure (20) includes a spray element, which is installed in the cooling chamber. The liquid sprayed by the spray element is used to cool the mercury vapor. The mercury-contaminated soil treatment system also includes: A heat exchange structure (70) is provided, wherein the heat exchange inlet of the heat exchange structure (70) is used to introduce liquid located between the mercury suspension and the bottom mud, and the heat exchange outlet of the heat exchange structure (70) is connected to the spray element.

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