CN113290037A

CN113290037A - Method and device for treating soil or bottom mud polluted by white phosphorus

Info

Publication number: CN113290037A
Application number: CN202110468601.5A
Authority: CN
Inventors: 郭学军
Original assignee: Beijing Normal University
Current assignee: Beijing Normal University
Priority date: 2021-04-28
Filing date: 2021-04-28
Publication date: 2021-08-24

Abstract

The invention relates to the technical field of contaminated soil restoration, in particular to a method and a device for treating soil or bottom mud contaminated by white phosphorus. The treatment method comprises the steps of mixing the soil or the bottom mud polluted by white phosphorus with water, heating and stabilizing at 40-100 ℃, and aerating by using an oxygen-containing gas source; mixing the soil or the bottom mud polluted by the white phosphorus with water, and then carrying out the treatment, so that the white phosphorus can be converted into pentavalent phosphate, and further the treatment of the soil or the bottom mud polluted by the white phosphorus is realized; meanwhile, the pentavalent phosphate is used as a beneficial fertilizer to be left in soil or bottom mud, so that resource utilization is realized. The method can easily remove the white phosphorus in the soil or the bottom mud by adjusting the treatment method, and the removal rate reaches more than 99.5 percent.

Description

Method and device for treating soil or bottom mud polluted by white phosphorus

Technical Field

The invention relates to the technical field of contaminated soil restoration, in particular to a method and a device for treating soil or bottom mud contaminated by white phosphorus.

Background

White phosphorus, also known as yellow phosphorus, is a highly toxic chemical. Some enterprises producing white phosphorus pour the byproduct phosphorus sludge into nearby farmlands or ponds, causing white phosphorus pollution of soil or bottom sludge; after a part of phosphorus chemical enterprises are moved, the soil on the old field is often polluted by more serious white phosphorus. However, the ignition point of white phosphorus is extremely low, and spontaneous combustion can be realized at 40 ℃; the semilethal dose of white phosphorus is only 50mg, which is twice as high as the lethal toxicity of traditional poison arsenic. It can be seen that there are significant fire and health risks associated with new land use projects such as real estate development in unrepaired white phosphorus contaminated sites.

CN106345798A discloses a method for treating soil contaminated by yellow phosphorus, which comprises the steps of physically stirring the soil contaminated by yellow phosphorus into slurry and reasonably screening, activating yellow phosphorus particles by using an oxidant through the principle of chemical reaction, improving the specific surface area of the yellow phosphorus particles, improving the surface activity of the yellow phosphorus particles, and then converting high-toxicity yellow phosphorus into nontoxic phosphate through disproportionation by using a disproportionation reaction agent and other processes; that is, an excessive amount of an oxidizing agent is added to soil contaminated with white phosphorus to oxidize the white phosphorus into phosphoric acid, and the remaining white phosphorus is reacted with a disproportionation agent (alkali) to become phosphorus pentoxide. However, the technical solution has the disadvantages that: the dosage of the oxidant is up to 1-5% of the mass of the soil, and the dosage of the disproportionation agent (alkali) is up to 2-10% of the mass of the soil; the use of excessive oxidant and disproportionation agent (alkali) not only increases the repair cost, but also has the more serious problem that the organic matter and acid-base balance of the soil are destroyed, so that the soil loses the capability of supporting plant growth; in addition, the disproportionation process can also generate extremely toxic gas of phosphine, so that the technical scheme has great safety and health risks.

In view of this, the invention is particularly proposed.

Disclosure of Invention

The invention aims to provide a method for treating soil or substrate sludge polluted by white phosphorus, which can effectively convert the white phosphorus in the soil or the substrate sludge into pentavalent phosphate. Another object of the invention is to provide an apparatus which can be used to implement the above-mentioned treatment method.

Specifically, the invention provides the following technical scheme:

the invention provides a method for treating soil or bottom mud polluted by white phosphorus, which comprises the steps of mixing the soil or bottom mud polluted by the white phosphorus with water, heating and stabilizing at 40-100 ℃, and aerating by using an oxygen-containing gas source.

The invention unexpectedly discovers that the treatment is carried out after the soil or the bottom mud polluted by the white phosphorus is mixed with water, so that the white phosphorus can be converted into pentavalent phosphate, and the treatment of the soil or the bottom mud polluted by the white phosphorus is further realized; meanwhile, the pentavalent phosphate is used as a beneficial fertilizer to be left in soil or bottom mud, so that resource utilization is realized.

In order to further improve the removal rate of white phosphorus, the treatment conditions are optimized in the invention, and the method specifically comprises the following steps:

preferably, the liquid-solid ratio of the soil or the bottom mud polluted by the white phosphorus to the water is 1: 1-5: 1.

preferably, the soil or the bottom mud polluted by the white phosphorus is mixed with water, heated and stabilized at 60-90 ℃, and aerated for 1-48 hours by using an oxygen-containing gas source.

Aiming at the reaction system of the invention, when the liquid-solid ratio of the soil or the bottom mud polluted by the white phosphorus to the water is 1: 1-5: 1(ml/g), heating to 60-90 ℃ and aerating for 1-48 h, wherein the removal rate of white phosphorus is higher.

Preferably, the oxygen-containing gas source is air or oxygen.

Preferably, the aeration mode is blast aeration and/or jet aeration;

preferably, the aeration is performed under stirring; the stirring speed is 50-500 rpm; stirring is carried out while hydrothermal aeration is carried out, so that white phosphorus can be fully contacted with an oxygen-containing gas source, and further the white phosphorus can be rapidly converted into pentavalent phosphate.

Preferably, an oxidizing agent is added to the aerated treatment product.

The invention also finds that the addition of the oxidant to the aerated treatment product can remove a small amount of white phosphorus remaining in the soil or the substrate sludge.

Further, the oxidant is selected from one or more of potassium permanganate, hydrogen peroxide, sodium hypochlorite, chlorine dioxide, chlorine and persulfate.

Furthermore, the amount of the oxidant is 0.1-10 g/kg based on the total mass of the soil or the substrate sludge polluted by the white phosphorus.

The reaction system of the invention is matched with the oxidant as described above, and when the dosage of the oxidant is 0.1-10 g/kg, a small amount of white phosphorus remained in the soil or the bottom mud can be removed completely.

Preferably, the treatment method further comprises the step of adding hydrated lime to the soil or the substrate sludge after the aeration treatment.

Preferably, the treatment method further comprises the step of adding hydrated lime to the soil or substrate sludge oxidized by the oxidizing agent.

In the technical scheme, the slaked lime is added into the soil or the bottom mud to adjust the pH value of the soil or the bottom mud, so that the soil or the bottom mud can recover the state before being polluted to the maximum extent.

Preferably, the concentration of the white phosphorus is 0.01 to 100g/kg based on the total mass of the soil or the sediment contaminated by the white phosphorus.

The treatment method provided by the invention is particularly suitable for the soil or the bottom mud polluted by the white phosphorus with the concentration.

Thus, the treatment of the soil or the bottom mud polluted by the white phosphorus is realized; the treated mud water can obtain clean soil or bottom mud after solid-liquid separation, and the separated water can be recycled repeatedly; the solid-liquid separation mode can adopt the conventional method in the field, such as centrifugal machine separation, plate-frame filter pressing, belt filter pressing, stacked screw machine separation and the like.

The invention also provides a device; the apparatus may be used to implement the above-described processing method.

Specifically, the apparatus comprises:

a hydrothermal aeration reaction tank; and the number of the first and second groups,

a heat source providing device for providing a heat source for the hydrothermal aeration reaction tank,

the gas source providing device is connected with the inlet of the hydrothermal aeration reaction tank through a pipeline and is used for providing a gas source for the hydrothermal aeration reaction tank,

and the flue gas absorption device is connected with the outlet of the hydrothermal aeration reaction tank through a pipeline and is used for absorbing the flue gas generated by the hydrothermal aeration reaction tank.

When the device is used for treating the soil or the bottom mud polluted by the white phosphorus, hot gas generated in the hydrothermal aeration reaction tank flows back to the hydrothermal aeration reaction tank through the pipeline for continuous heating and aeration, and a small amount of phosphorus pentoxide smoke in the hot gas is absorbed again by water in the hydrothermal aeration reaction tank while the heat and the energy required by the hydrothermal aeration are fully utilized and saved.

In the invention, the flue gas absorption device can absorb part of phosphorus pentoxide flue gas overflowing from the hydrothermal aeration reaction tank; water or alkaline water solution can be selected as the absorption liquid of the smoke absorption device.

The invention has the beneficial effects that:

the method can easily remove the white phosphorus in the soil or the bottom mud by adjusting the treatment method, and the removal rate reaches more than 99.5 percent.

Drawings

FIG. 1 is a schematic view of an apparatus provided by the present invention;

in the figure: 1. a hydrothermal aeration reaction tank; 2. a heat source providing device; 3. a gas source providing device; 4. a flue gas absorption device.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

The examples do not show the specific techniques or conditions, according to the technical or conditions described in the literature in the field, or according to the product specifications. The reagents or instruments used are conventional products available from regular distributors, not indicated by the manufacturer.

Example 1

The embodiment provides a method for treating soil polluted by white phosphorus, which comprises the following steps:

100g of contaminated soil with a white phosphorus concentration of 10g/kg and 200mL of water were placed in a 500mL round bottom mechanically stirred reactor. And (3) putting the reactor into a heat collection type constant temperature heating stirrer, stabilizing the temperature at 70-80 ℃, and stirring at the rotating speed of 200 rpm. An air pipe connected with an air pump is inserted into the bottom of the reactor for aeration for 4 hours, the outlet of the reactor is connected with an absorber filled with 200ml of alkali liquor (the concentration of sodium hydroxide is 10%) through a rubber pipe, and after the aeration is finished for 4 hours, 1.0g/kg of potassium permanganate is added into the soil suspension for continuous reaction for 4 hours. And (3) centrifuging and freeze-drying the soil sample, and measuring the concentration of white phosphorus in the soil sample after hydrothermal aeration and potassium permanganate oxidation treatment. Analysis shows that the residual concentration of white phosphorus in the soil after hydrothermal aeration for 4 hours is 68mg/kg, and the removal rate of the white phosphorus is as high as 99.3 percent; the residual concentration of the white phosphorus after the oxidation treatment by potassium permanganate is 21mg/kg, and the total removal rate of the white phosphorus is up to 99.8 percent.

Example 2

1 ton of polluted soil with the white phosphorus pollution concentration of 10g/kg and 2 cubic meters of water are put into a 5 cubic meter round bottom mechanical stirring reaction tank. The heating temperature of the electric heating jacket is stabilized at 80-85 ℃, and the rotating speed is 200 rpm. Inserting a vacuum tube connected with an air blower into the bottom of the reactor for aeration for 10h, connecting an outlet of the reactor with an absorber containing 200L of alkali liquor (the concentration of sodium hydroxide is 10%) through a rubber tube, and adding 1.0g/kg of potassium permanganate into the soil suspension after the aeration is finished for 10h to continue to react for 4 h. And (3) centrifuging and freeze-drying the soil sample, and measuring the concentration of white phosphorus in the soil sample after hydrothermal aeration and potassium permanganate oxidation treatment. Analysis shows that the residual concentration of white phosphorus in the soil after 10 hours of hydrothermal aeration is 89mg/kg, and the removal rate of the white phosphorus is as high as 99.1 percent; the residual concentration of the white phosphorus after the oxidation treatment by potassium permanganate is 26mg/kg, and the total removal rate of the white phosphorus is up to 99.7 percent.

Example 3

The embodiment provides a method for treating bottom mud polluted by white phosphorus, which comprises the following steps:

100g of contaminated substrate sludge with a white phosphorus contamination concentration of 5g/kg and 200mL of water were taken in a 500mL round bottom mechanically stirred reactor. And (3) putting the reactor into a heat collection type constant temperature heating stirrer, wherein the temperature is stabilized at 80-85 ℃, and the stirring speed is 200 rpm. Inserting an air pipe connected with an air pump into the bottom of the reactor for aeration for 4h, connecting an outlet of the reactor with an absorber containing 200ml of alkali liquor (the concentration of sodium hydroxide is 10%) through a rubber pipe, and adding 0.5g/kg of hydrogen peroxide into the soil suspension after the aeration is finished for continuous reaction for 8 h. And (3) centrifuging and freeze-drying the soil sample, and measuring the concentration of white phosphorus in the soil sample after hydrothermal aeration and potassium permanganate oxidation treatment. Analysis shows that the residual concentration of white phosphorus in the soil after hydrothermal aeration for 4 hours is 34mg/kg, and the removal rate of the white phosphorus is as high as 93.2 percent; the residual concentration of the white phosphorus after the oxidation treatment by potassium permanganate is 10mg/kg, and the total removal rate of the white phosphorus is up to 99.8 percent.

Example 4

This embodiment provides an apparatus for implementing the processing method of embodiments 1 to 3;

specifically, as shown in fig. 1, the apparatus includes:

a hydrothermal aeration reaction tank 1; and the number of the first and second groups,

a heat source providing device 2 for providing a heat source for the hydrothermal aeration reaction tank,

the gas source providing device 3 is connected with the inlet of the hydrothermal aeration reaction tank through a pipeline and is used for providing a gas source for the hydrothermal aeration reaction tank,

and the flue gas absorption device 4 is connected with the outlet of the hydrothermal aeration reaction tank through a pipeline and is used for absorbing the flue gas generated by the hydrothermal aeration reaction tank.

Comparative example 1

This comparative example provides a treatment of white phosphorus contaminated soil, differing from example 1 only in that: the reactor was directly aerated at room temperature (15 ℃) for 4h without heating.

The measurement result shows that the residual concentration of the white phosphorus in the soil is as high as 7.6 g/kg; it can be seen that the removal rate of the aerated white phosphorus at room temperature is only 24%.

Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that many modifications and improvements can be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. A method for treating soil or bottom mud polluted by white phosphorus is characterized in that the soil or bottom mud polluted by white phosphorus is mixed with water, heated and stabilized at 40-100 ℃, and aerated by an oxygen-containing gas source.

2. The process according to claim 1, characterized in that the liquid-solid ratio of the soil or substrate sludge contaminated by white phosphorus to water, expressed in ml/g, is 1: 1-5: 1.

3. the treatment method according to claim 2, characterized in that the soil or the bottom mud polluted by white phosphorus is mixed with water, heated and stabilized at 60-90 ℃, and simultaneously aerated for 1-48 h by an oxygen-containing gas source;

preferably, the oxygen-containing gas source is air or oxygen;

more preferably, the aeration is blast aeration and/or jet aeration.

4. The treatment method according to any one of claims 1 to 3, wherein the aeration is performed under stirring; the stirring speed is 50-500 rpm.

5. A treatment method according to any one of claims 1 to 4, wherein an oxidizing agent is added to the aerated treatment product.

6. The treatment method according to claim 5, wherein the oxidant is one or more selected from potassium permanganate, hydrogen peroxide, sodium hypochlorite, chlorine dioxide, chlorine gas and persulfate;

preferably, the amount of the oxidant is 0.1-10 g/kg based on the total mass of the soil or the substrate sludge polluted by the white phosphorus.

7. A treatment method according to any one of claims 1 to 4, further comprising a step of adding hydrated lime to the soil or the bottom mud after the aeration treatment.

8. The treatment method according to claim 5 or 6, further comprising the step of adding hydrated lime to the soil or substrate sludge oxidized by the oxidizing agent.

9. The method according to any one of claims 1 to 8, wherein the concentration of white phosphorus is 0.01 to 100g/kg based on the total mass of the soil or the bottom mud contaminated with white phosphorus.

10. An apparatus, comprising: