CN110434160B

CN110434160B - Remediation method for heavy metal contaminated soil

Info

Publication number: CN110434160B
Application number: CN201910767994.2A
Authority: CN
Inventors: 武爱彬
Original assignee: Institute Of Geography Hebei Academy Of Sciences
Current assignee: Institute Of Geography Hebei Academy Of Sciences
Priority date: 2019-08-20
Filing date: 2019-08-20
Publication date: 2020-05-26
Anticipated expiration: 2039-08-20
Also published as: CN110434160A

Abstract

The invention relates to a method for restoring heavy metal contaminated soil, which comprises the following steps: A. preparing a soil remediation agent; B. carrying out deep ploughing treatment on the soil by using a deep ploughing machine, and uniformly applying a soil repairing agent to the soil, wherein the using amount of the soil repairing agent is 30-50 kg/mu; C. and (C) repeating the step (B) once every 2-3 days, wherein the dosage of the soil remediation agent is reduced by 50% compared with the dosage of the soil remediation agent at the last time when the step (B) is repeated every time, and the soil remediation is completed after 2-3 times. The invention can improve the defects of the prior art, improve the adsorption effect of the repairing agent on heavy metals and reduce the using amount of the repairing agent.

Description

Remediation method for heavy metal contaminated soil

Technical Field

The invention relates to the technical field of environmental protection, in particular to a method for restoring heavy metal contaminated soil.

Background

With the development of industrialization, heavy metal pollution gradually becomes a main pollution source of soil pollution. Heavy metal pollution of soil has serious impact on human health due to the accumulation of heavy metal elements in plants and human bodies. The invention of Chinese patent CN 105885863B proposes a method for repairing soil by using medical stone, which can adsorb and remove various heavy metal elements in soil because of good adsorption property of medical stone. However, the actual using amount of the repairing agent is large because the binding rate of the phytic acid and the medical stone is not high when the repairing agent is prepared.

Disclosure of Invention

The invention provides a method for restoring heavy metal contaminated soil, which can overcome the defects of the prior art, improve the adsorption effect of a restoring agent on heavy metals and reduce the using amount of the restoring agent.

In order to solve the technical problems, the invention provides the following technical scheme.

A method for restoring heavy metal contaminated soil comprises the following steps:

A. the preparation method of the soil remediation agent comprises the steps of,

the soil repairing agent comprises 1.5-3 wt% of citric acid, 4.5-6 wt% of sodium sulfite, 5-10 wt% of plant ash, 2-4 wt% of HEDTA, 10-15 wt% of bentonite, 1-1.5 wt% of calcium sulfate, 0.5-2 wt% of sodium silicate, 3-5 wt% of sodium polyacrylate, 25-30 wt% of modified medical stone and the balance of water;

B. carrying out deep ploughing treatment on the soil by using a deep ploughing machine, and uniformly applying a soil repairing agent to the soil, wherein the using amount of the soil repairing agent is 30-50 kg/mu;

C. and (C) repeating the step (B) once every 2-3 days, wherein the dosage of the soil remediation agent is reduced by 50% compared with the dosage of the soil remediation agent at the last time when the step (B) is repeated every time, and the soil remediation is completed after 2-3 times.

Preferably, the preparation of the modified medical stone comprises the following steps,

a1, crushing medical stone to 500-800 meshes;

a2, heating medical stone powder to 800 ℃, calcining for 20-30 min, and then standing and cooling to room temperature; heating medical stone powder to 500 ℃, calcining for 40-60 min, then putting into an aqueous solution containing 10 wt% of sodium dodecyl ether sulfate, cooling with water to normal temperature, taking out and air-drying;

a3, adding 5 wt% of talcum powder into Maifanitum powder to obtain modified Maifanitum.

Preferably, in the step A3, 5 wt% of talcum powder is added into the medical stone powder, and then 2 wt% of ferrous sulfate is added.

Preferably, the deep ploughing machine comprises a frame, a transmission shaft is mounted on the frame, a plurality of ploughing blades are mounted on the transmission shaft, a fertilizing box is mounted between every two adjacent ploughing blades, the transmission shaft penetrates through the fertilizing box, the top of the fertilizing box is connected with a feeding pipe, first through holes are formed in the side wall and the bottom of the fertilizing box respectively, stirring blades are arranged in the fertilizing box and mounted on the transmission shaft, and guide blades are obliquely fixed to the tops of the ploughing blades and convey soil to the fertilizing boxes on two sides.

Preferably, the stirring blade is provided with a plurality of second through holes perpendicular to the stirring blade, the stirring blade is also internally provided with blind holes parallel to the stirring blade, and the blind holes are communicated with the second through holes.

Preferably, the pipe mouth of the feeding pipe is symmetrically hinged with two baffles, the baffles are in sliding contact with the stirring blades, the baffles are connected with the inner wall of the feeding pipe through springs, and a guide plate is arranged above the baffles and hinged with the feeding pipe.

The invention has the beneficial effects that: the invention improves the adsorption capacity to heavy metal elements by improving the formula of the repairing agent. The medical stone is modified in a physical mode, so that the adsorption rate of the medical stone to heavy metal elements is improved, and the aim of further reducing the using amount of the repairing agent is fulfilled.

In the process of repairing soil, the invention realizes the full mixing of the repairing agent and the soil in the application box by improving the deep ploughing machine and utilizing the turning and conveying functions of the ploughing knife and the stirring blade on the soil. The through hole structure on the stirring blade can realize the sufficient flow and mixing of soil and remediation agent in two directions. The opening and closing of the baffle are controlled by the rotation of the stirring blades, so that the repairing agent can be concentrated by the guide plate and enter the stirring blade area and more blind holes, and the repairing agent and soil can be fully mixed.

Drawings

Fig. 1 is a structural diagram of a deep ploughing machine in a specific embodiment of the invention.

FIG. 2 is a block diagram of a paint tank according to an embodiment of the present invention.

Detailed Description

The following describes the operation of the present invention in detail with reference to specific examples.

A. the preparation method of the soil remediation agent comprises the steps of,

the soil remediation agent comprises 2 wt% of citric acid, 5.5 wt% of sodium sulfite, 5 wt% of plant ash, 2 wt% of HEDTA, 15 wt% of bentonite, 1 wt% of calcium sulfate, 1.3 wt% of sodium silicate, 5 wt% of sodium polyacrylate, 28 wt% of modified medical stone and the balance of water;

B. carrying out deep ploughing treatment on the soil by using a deep ploughing machine, and uniformly applying a soil repairing agent to the soil, wherein the using amount of the soil repairing agent is 35 kg/mu;

C. and (C) repeating the step (B) once every 3 days, wherein the dosage of the soil remediation agent is reduced by 50 percent compared with the dosage of the soil remediation agent at the last time when the step (B) is repeated every time, and the soil remediation is completed after 2 times.

The preparation method of the modified medical stone comprises the following steps,

a1, pulverizing Maifanitum to 500 meshes;

a2, heating medical stone powder to 800 ℃, calcining for 20min, and then standing and cooling to room temperature; heating medical stone powder to 500 ℃ for calcining for 60min, then putting the medical stone powder into an aqueous solution containing 10 wt% of sodium dodecyl ether sulfate, cooling the mixture to normal temperature by water, taking out the mixture and drying the mixture in the air;

a3, adding 5 wt% of talcum powder into Maifanitum powder, and adding 2 wt% of ferrous sulfate to obtain modified Maifanitum.

Referring to fig. 1-2, the deep ploughing machine comprises a frame 1, a transmission shaft 4 is installed on the frame 1, a plurality of ploughing blades 2 are installed on the transmission shaft 4, a dressing box 3 is installed between two adjacent ploughing blades 2, the transmission shaft 4 penetrates through the dressing box 3, the top of the dressing box 3 is connected with a feeding pipe 5, the side wall and the bottom of the dressing box 3 are respectively provided with a first through hole 7, a stirring blade 6 is arranged in the dressing box 3, the stirring blade 6 is installed on the transmission shaft 4, a guide vane 8 is obliquely fixed at the top of the ploughing blade 2, and the guide vane 8 conveys soil to the dressing boxes 3 on two sides. The stirring blade 6 is provided with a plurality of second through holes 9 perpendicular to the stirring blade 6, blind holes 10 parallel to the stirring blade 6 are further arranged in the stirring blade 6, and the blind holes 10 are communicated with the second through holes 9. The mouth of the feeding pipe 5 is symmetrically hinged with two baffle plates 11, the baffle plates 11 are in sliding contact with the stirring blades 6, the baffle plates 11 are connected with the inner wall of the feeding pipe 5 through springs 12, a guide plate 13 is arranged above the baffle plates 11, and the guide plate 13 is hinged with the feeding pipe 5.

Example 3 of the prior art patent mentioned in the background is used as a comparative example to compare with the inventive example, and the results are as follows.

Therefore, the remediation method can be used for effectively adsorbing and removing the heavy metal elements in the soil under the condition of reducing the using amount of the remediation agent.

The foregoing is illustrative of the present invention and it will be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is to be construed as being limited only by the claims and their equivalents.

Claims

1. The method for restoring the heavy metal contaminated soil is characterized by comprising the following steps: A. preparing a soil repairing agent, wherein the soil repairing agent comprises 1.5-3 wt% of citric acid, 4.5-6 wt% of sodium sulfite, 5-10 wt% of plant ash, 2-4 wt% of HEDTA, 10-15 wt% of bentonite, 1-1.5 wt% of calcium sulfate, 0.5-2 wt% of sodium silicate, 3-5 wt% of sodium polyacrylate, 25-30 wt% of modified medical stone and the balance of water; B. carrying out deep ploughing treatment on the soil by using a deep ploughing machine, and uniformly applying a soil repairing agent to the soil, wherein the using amount of the soil repairing agent is 30-50 kg/mu; C. repeating the step B once every 2-3 days, wherein the dosage of the soil remediation agent is reduced by 50% when the step B is repeated every time compared with the dosage of the soil remediation agent at the last time, and the soil remediation is completed after 2-3 times;

the preparation method of the modified medical stone comprises the following steps of A1, crushing the medical stone to 500-800 meshes; a2, heating medical stone powder to 800 ℃, calcining for 20-30 min, and then standing and cooling to room temperature; heating medical stone powder to 500 ℃, calcining for 40-60 min, then putting into an aqueous solution containing 10 wt% of sodium dodecyl ether sulfate, cooling with water to normal temperature, taking out and air-drying; a3, adding 5 wt% of talcum powder into Maifanitum powder to obtain modified Maifanitum.

2. The method for remediating heavy metal contaminated soil as recited in claim 1, wherein in the step A3, 5 wt% of talc is added to the Maifanitum powder, and then 2 wt% of ferrous sulfate is added.

3. The heavy metal contaminated soil remediation method according to claim 1, wherein the deep ploughing machine comprises a frame (1), a transmission shaft (4) is mounted on the frame (1), a plurality of ploughing blades (2) are mounted on the transmission shaft (4), a fertilizing box (3) is mounted between every two adjacent ploughing blades (2), the transmission shaft (4) penetrates through the fertilizing box (3), a feeding pipe (5) is connected to the top of the fertilizing box (3), first through holes (7) are respectively formed in the side wall and the bottom of the fertilizing box (3), stirring blades (6) are arranged in the fertilizing box (3), the stirring blades (6) are mounted on the transmission shaft (4), guide vanes (8) are obliquely fixed to the tops of the ploughing blades (2), and the soil is conveyed to the fertilizing boxes (3) on two sides by the guide vanes (8).

4. The method for remediating heavy metal contaminated soil as recited in claim 3, wherein the stirring blade (6) is provided with a plurality of second through holes (9) perpendicular to the stirring blade (6), a blind hole (10) parallel to the stirring blade (6) is further formed in the stirring blade (6), and the blind hole (10) is communicated with the second through holes (9).

5. The method for restoring the soil polluted by the heavy metal according to claim 4, wherein the two baffle plates (11) are symmetrically hinged to the opening of the feeding pipe (5), the baffle plates (11) are in sliding contact with the stirring blade (6), the baffle plates (11) are connected with the inner wall of the feeding pipe (5) through springs (12), a guide plate (13) is arranged above the baffle plates (11), and the guide plate (13) is hinged to the feeding pipe (5).