Magnetic biochar soil remediation agent for heavy metal pollution of soil, and preparation method and application thereof

Abstract

The invention belongs to the technical field of soil remediation, and discloses a magnetic charcoal soil remediation agent for soil heavy metal pollution, a preparation method thereof and application of the magnetic charcoal soil remediation agent in polluted soil remediation. The magnetic biochar soil remediation agent is prepared through the following steps that solid waste rich in ferromagnetic iron / cobalt / nickel compounds is crushed and then subjected to chloridizing roasting; magnetic particles are collected through magnetic separation; and then the magnetic particles are mixed with agricultural wastes or a mixture of the agricultural wastes and urea according to a ratio, and then carbonization, ball milling and magnetic separation are carried out. The invention further discloses a method for repairing soil by adopting the magnetic biochar. The method of secondary ploughing and secondary irrigation is adopted, the magnetic biochar and the discharged floating biochar are separated through a magnetic rotary knife, soil heavy metal can be effectively removed, and a new way is provided for treatment of soil heavy metal pollution.

Description

technical field [0001] The invention relates to the technical field of soil remediation, in particular to a magnetic biochar soil remediation agent for soil heavy metal pollution and its preparation method and application. Background technique [0002] Iron tailings are the waste after mineral processing and are the main component of industrial solid waste. In industrial production, a lot of red mud, steel slag, welding slag, scrap iron slag and other solid waste rich in ferromagnetic iron / cobalt / nickel compounds will be produced. A large number of iron tailings and various solid wastes rich in oxides such as iron, cobalt and nickel are idle and discarded, which is not only a waste of resources, but also causes serious harm and risks to the environment during the long-term environmental change process. How to properly dispose of solid waste and increase its added value is crucial to realizing the harmlessness and resource utilization of solid waste. Similarly, a large amou...

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Problems solved by technology

Chinese patent application CN201811427866.5 discloses a roasting treatment method of iron tailings. In this method, the iron tailings are roasted in an inert gas atmosphere by roasting, and the volatilized flue gas is recovered to obtain metal chlorides, and the residue is further magnetically separated to obtain magnets. ore; the invention realizes the magnetic separation of iron tailings and the recovery of valuable metals lead, copper and zinc through the control of specific inert gas, chlorinating agent addition amount and roasting temperature rise and fall program, which fundamentally reduces the iron The tailings treatment process has a lot of pollution and affects the recovery of metals in the flue gas. It is easy to operate, low in cost, and has obvious benefits for iron tailings reduction and resource utilization; although this method can reduce and recycle iron tailings mines, but have not yet been prepared into high value-added materials

The use of biochar to remediate soil has been widely recognized. Traditional biochar remediation of soil has certain timeliness, high cost, and low remediation efficiency, and cannot reduce the content of heavy metals in the soil.

[0005] Chinese Patent Authorization Announcement No. CN104971697B discloses a preparation and application method of a magnetic biochar material used to remove arsenic pollution in water bodies. The method obtains CRHO by carbonizing chaff modification, and prepares loaded nano-Fe 3 o 4 Modified carbonized rice husk particles; magnetic biochar CRHO-Fe in this invention 3 o 4 Not only has a high removal rate for arsenic-containing wastewater, but also is cheap and has no secondary pollution. It is convenient for magnetic biochar CRHO-Fe 3 o 4 Multiple recycling and reuse can be widely used in the field of medium and low concentration arsenic-containing wastewater treatment; this method is mainly used for the removal of As in the water system, and the function is relatively single

Chinese Patent Authorization Notice No. CN111570494B discloses a method for remediating heavy metal-contaminated soil. 0.5-2% of modified magnetic biochar is added to the soil to float the modified magnetic biochar out of the water, and then the enriched free Cd and soil viscous The magnetic biochar can be recycled to achieve the purpose of reducing the total Cd in the soil; the modified magnetic biochar is to crush the biochar raw material and impregnate it with Fe-containing 2+ In the solution, shake and filter to obtain solid raw materials, dry and pyrolyze to obtain magnetic biochar, and prepare magnetic biochar-loaded Ca-Al hydrotalcite adsorbent by hydrothermal method, and then modify it with chitosan; Although the method takes advantage of the lightness of biochar, its magnetization effect is not considered. Obviously, the floating amount of soil after mixing with biochar is small, and it cannot be removed in large quantities. In addition, the soil is usually compound pollution. In this method, the magnetic Biochar only has a good effect on Cd, the effects of other toxic metals are unknown, and the safety of soil cultivation is also unknown

[0006] At present, the method of using solid waste such as tailings and agricultural waste to prepare magnetic biochar and its application in soil remediation have not been reported yet.

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