Remediation method for heavy metal combined pollution soil of earth-process zinc smelting site by adopting passivator compound

Abstract

The invention belongs to the field of passivation and remediation of heavy metal contaminated soil, and discloses a remediation method for heavy metal compound contaminated soil of an earth-process zinc smelting site by adopting a passivator compound. The method comprises the steps that a passivator compound is scattered into soil of the soil-method zinc smelting site, the scattering dosage is 100-600 kg / mu, ploughing is carried out, the passivator compound is evenly turned into the soil, after natural stabilization is carried out for 6-12 months, sampling is carried out, and the heavy metal concentration is analyzed; the passivator compound comprises more than one of a biochar material and a natural mineralizer, and the addition mass ratio of the biochar material to the natural mineralizer is (1-3): 1; the natural mineralizer is selected from more than one of sepiolite and hydroxyl phospholime. In the treatment method, the passivator compound is added to increase the pH value of the soil, so that the biological effective state content of various heavy metals in the soil is reduced, and the amount of various heavy metals absorbed by plants is reduced.

Description

Technical Field

[0001] The invention belongs to the field of passivation and remediation of heavy metal contaminated soil, and particularly relates to a method for remediating heavy metal compound contaminated soil in a soil zinc smelting site by using a passivator complex. Background Art

[0002] At present, the situation of heavy metal pollution in cultivated land in China is severe, showing the remarkable characteristics of "large quantity, wide area, compound accumulation". The polluting elements are mainly cadmium, arsenic, lead, mercury, and chromium. Among them, cadmium has become a key control object due to its high mobility and biological toxicity. The cadmium content in the soil of some sewage irrigation areas is as high as 228 mg / kg, far exceeding the national limit standard. Heavy metal pollution directly destroys the soil microbial community structure, reduces the ability of organic matter decomposition and the efficiency of nitrogen and phosphorus cycling, resulting in a 20%-40% decline in soil fertility. Taking cadmium pollution as an example, it inhibits the root development and photosynthesis of plants, causing a 15%-30% reduction in rice yield. At the same time, it changes the gene expression of crops, resulting in a heavy metal exceeding standard rate of agricultural products as high as 10%-25%. After the heavy metals in the polluted soil enter the water body through surface runoff, they can cause chronic poisoning of aquatic organisms. For example, the toxicity of mercury increases by a thousand times after methylation in fish, threatening the stability of the aquatic food chain. Heavy metals are enriched through the "soil-crop-human body" chain, causing chronic health damage. The half-life of cadmium in the human body is as long as 10-30 years. Long-term intake of low-dose cadmium can cause renal tubular dysfunction and osteomalacia; lead exposure causes damage to the nervous system development of children. For every 10 μg / dL increase in blood lead concentration, the IQ drops by 2-3 points. More seriously, arsenic, chromium (VI), etc. are highly carcinogenic. There is a significant spatial correlation between the high-incidence areas of cancer in China and the distribution of soil heavy metal pollution. The incidence of digestive tract cancer in some residents of sewage irrigation areas is 3-5 times higher than that in clean areas. From this perspective, the rectification work of heavy metal pollution in China is urgent.

[0003] The existing soil heavy metal pollution remediation technologies mainly include physical remediation technology, chemical remediation technology, biological remediation technology and their combined remediation technology. Among them, the chemical fixation technology established by adding passivators in chemical remediation technology has broad application prospects due to its advantages of low cost, simple operation, quick effect, non-destruction of soil structure and environmental friendliness. Developing highly efficient and widely applicable passivators has become the difficulty in constructing this technology. The existing passivator remediation technologies have significant differences in the remediation effects on different heavy metals and cannot meet the passivation and remediation needs of compound heavy metal contaminated soil. Summary of the Invention

[0004] Aiming at the above defects existing in the prior art, the present invention aims to provide an efficient and non-secondary environmental pollution soil heavy metal pollution passivator, and provide a method for remediating heavy metal compound contaminated soil in a soil zinc smelting site by using a passivator complex.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for remediating heavy metal - contaminated soil in a local zinc - smelting site using a passivator complex. The passivator complex is spread into the soil of the local zinc - smelting site, and the spreading dosage is 100 - 600 kg / mu, followed by plowing to evenly incorporate the passivator complex into the soil. After natural stabilization for 6 - 12 months, soil samples are taken for analyzing heavy metal concentrations.

[0007] The passivator complex includes one or more of biochar materials and natural mineral compounds, and the mass ratio of their addition amounts is 1 - 3:1; the natural mineral compounds are selected from one or more of sepiolite and hydroxyapatite.

[0008] The heavy metals in the present invention include Cr, Cu, Zn, As, Cd, and Pb.

[0009] In the above method, the biochar material includes one or more of rice - straw biochar, corn - straw biochar, and walnut - shell biochar.

[0010] In the above method, when the biochar material is two of rice - straw biochar, corn - straw biochar, and walnut - shell biochar, the addition amounts satisfy a mass ratio of 1 - 5:1 - 5, preferably 1:1.

[0011] In the above method, when the biochar material is rice - straw biochar, corn - straw biochar, and walnut - shell biochar, the addition amounts satisfy a mass ratio of 1 - 5:1 - 5:1 - 5, preferably 1:1:1.

[0012] In the above method, the number of times the passivator complex is spread is 6 - 10 times, preferably 6 times.

[0013] In the above method, the depth of plowing is 15 - 40 cm, preferably 20 cm.

[0014] The present invention provides a preparation method of a passivator complex, specifically as follows:

[0015] (1) Air - dry, crush, and then sieve the biochar material under natural conditions to obtain biochar material powder;

[0016] (2) Place the biochar material powder in an atmosphere furnace, and the furnace is filled with high - purity nitrogen to provide an oxygen - limited environment; the heating rate of the furnace is set at 5 - 10 °C / min, and it is maintained at 400 - 550 °C for 2 - 3 h, and then naturally cooled to room temperature; then the obtained biochar material is ground and sieved.

[0017] (3) Wash the biochar material obtained in step (2) repeatedly with clean water. After natural air drying, mix it evenly with natural mineral compounds, and then place it in an oven to dry at 60-65 °C until constant weight. After cooling to room temperature, a passivator complex is obtained.

[0018] Further, in step (1), the sieving is through a 20-60 mesh sieve.

[0019] Further, in step (2), the sieving is through a 100-120 mesh sieve.

[0020] Further, in step (1), the biochar material is selected from one or more of corn straw, rice straw, and walnut shell.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] 1. Realize the safe utilization of severely heavy metal-contaminated soil;

[0023] 2. The passivator complex is added to the contaminated soil by plowing, making the soil mixing more uniform;

[0024] 3. Adding the passivator complex increases the soil pH value, thereby reducing the content of various heavy metal bioavailable forms in the soil and reducing the amount of various heavy metals absorbed by plants. Description of the Drawings

[0025] Figure 1 It is the soil pH distribution map under different passivator complex treatments in Examples 1-15;

[0026] Figure 2 It is the soil bioavailable Cr concentration distribution map under different passivator complex treatments in Examples 1-15;

[0027] Figure 3 It is the soil bioavailable Cu concentration distribution map under different passivator complex treatments in Examples 1-15;

[0028] Figure 4 It is the soil bioavailable Zn concentration distribution map under different passivator complex treatments in Examples 1-15;

[0029] Figure 5 It is the soil bioavailable As concentration distribution map under different passivator complex treatments in Examples 1-15;

[0030] Figure 6 It is the soil bioavailable Cd concentration distribution map under different passivator complex treatments in Examples 1-15;

[0031] Figure 7 It is the soil bioavailable Pb concentration distribution map under different passivator complex treatments in Examples 1-15. Detailed implementation mode

[0032] The present invention will be further described in detail below in conjunction with specific embodiments. However, the implementation mode of the present invention is not limited thereto. For process parameters not specifically noted, conventional techniques can be referred to.

[0033] Example 1

[0034] (1) Air-dry the corn straw under natural conditions, crush the dried material in a crusher, and then sieve it through a 20-60 mesh sieve to obtain corn straw powder.

[0035] (2) Place the corn straw powder in an atmosphere furnace. The furnace provides an oxygen-limited environment by introducing high-purity nitrogen; the furnace is set with a heating rate of 5-10 °C / min, maintained at 400-550 °C for 2-3 h, and then naturally cooled to room temperature; then grind the obtained corn straw biochar and sieve it through a 100-120 mesh sieve.

[0036] (3) Weigh a certain amount of corn straw biochar, wash it repeatedly with clear water for more than 3 times, air-dry it naturally, and then uniformly mix it with hydroxyapatite in a mass ratio of 1:1. After that, put it into an oven and dry it at 60-65 °C to constant weight. After cooling to room temperature, a passivator compound is obtained.

[0037] (4) Spread the passivator compound into the soil, with a dosage of 100 kg / mu each time, and then plow the soil to uniformly turn the passivator compound into the soil, and continuously spread it 6 times. After natural stabilization for 6 months, sample and analyze the bioavailable concentration of heavy metals.

[0038] Example 2

[0039] (1) Air-dry the corn straw under natural conditions, crush the dried material in a crusher, and then sieve it through a 20-60 mesh sieve to obtain corn straw powder.

[0040] (2) Place the corn straw powder in an atmosphere furnace. The furnace provides an oxygen-limited environment by introducing high-purity nitrogen; the furnace is set with a heating rate of 5-10 °C / min, maintained at 400-550 °C for 2-3 h, and then naturally cooled to room temperature; then grind the obtained corn straw biochar and sieve it through a 100-120 mesh sieve.

[0041] (3) Weigh a certain amount of corn straw biochar, wash it repeatedly with clear water for more than 3 times, air-dry it naturally, and then uniformly mix it with hydroxyapatite in a mass ratio of 1:1. After that, put it into an oven and dry it at 60-65 °C to constant weight. After cooling to room temperature, a passivator compound is obtained.

[0042] (4) Spread the passivator complex into the soil at a dosage of 100 kg / mu, and then plow the soil to evenly incorporate the passivator complex into the soil. After natural stabilization for 6 months, sample and analyze the bioavailable concentration of heavy metals.

[0043] Example 3

[0044] (1) Air-dry the corn straw under natural conditions, crush the dried material in a crusher, and then sieve it through a 20-60 mesh sieve to obtain corn straw powder.

[0045] (2) Place the corn straw powder in an atmosphere furnace, and the furnace provides an oxygen-limited environment by introducing high-purity nitrogen; set the heating rate of the furnace at 5-10 °C / min, hold at 400-550 °C for 2-3 h, and then naturally cool to room temperature; then grind the obtained corn straw biochar and sieve it through a 100-120 mesh sieve.

[0046] (3) Weigh a certain amount of corn straw biochar, wash it repeatedly with clean water for more than 3 times, air-dry it naturally, and then evenly mix it with hydroxyapatite in a mass ratio of 1:1. After that, place it in an oven at 60-65 °C and dry it to constant weight. After cooling to room temperature, obtain the passivator complex.

[0047] (4) Spread the passivator complex into the soil at a dosage of 300 kg / mu, and then plow the soil to evenly incorporate the passivator complex into the soil. After natural stabilization for 6 months, sample and analyze the bioavailable concentration of heavy metals.

[0048] Example 4

[0049] (1) Air-dry the corn straw under natural conditions, crush the dried material in a crusher, and then sieve it through a 20-60 mesh sieve to obtain corn straw powder; air-dry the walnut shell under natural conditions, crush the dried material in a crusher, and then sieve it through a 20-60 mesh sieve to obtain walnut shell powder.

[0050] (2) Place the corn straw powder and walnut shell powder separately in an atmosphere furnace, and the furnace provides an oxygen-limited environment by introducing high-purity nitrogen; set the heating rate of the furnace at 5-10 °C / min, hold at 400-550 °C for 2-3 h, and then naturally cool to room temperature; then grind the obtained corn straw biochar and walnut shell biochar and sieve it through a 100-120 mesh sieve.

[0051] (3) Evenly mix the corn straw biochar and walnut shell biochar in a mass ratio of 1:1. After that, place it in an oven at 60-65 °C and dry it to constant weight. After cooling to room temperature, obtain the passivator complex.

[0052] (4) Spread the passivator complex into the soil at a dose of 100 kg / mu each time, and then plow the soil to evenly incorporate the passivator complex into the soil. Repeat this process 6 times. After natural stabilization for 6 months, take samples to analyze the bioavailable concentration of heavy metals.

[0053] Example 5

[0054] (1) Air-dry the corn straw under natural conditions, crush the dried material in a pulverizer, and then sieve it through a 20-60 mesh sieve to obtain corn straw powder; air-dry the walnut shell under natural conditions, crush the dried material in a pulverizer, and then sieve it through a 20-60 mesh sieve to obtain walnut shell powder.

[0055] (2) Place the corn straw powder and walnut shell powder separately in an atmosphere furnace. The furnace provides an oxygen-limited environment by introducing high-purity nitrogen. Set the heating rate of the furnace at 5-10 °C / min, maintain it at 400-550 °C for 2-3 h, and then naturally cool it to room temperature. Then grind the obtained corn straw biochar and walnut shell biochar and sieve them through a 100-120 mesh sieve.

[0056] (3) Uniformly mix the corn straw biochar and walnut shell biochar in a mass ratio of 1:1, then place them in an oven and dry them at 60-65 °C to constant weight. After cooling to room temperature, obtain the passivator complex.

[0057] (4) Spread the passivator complex into the soil at a dose of 100 kg / mu, and then plow the soil to evenly incorporate the passivator complex into the soil. After natural stabilization for 6 months, take samples to analyze the bioavailable concentration of heavy metals.

[0058] Example 6

[0059] (1) Air-dry the corn straw under natural conditions, crush the dried material in a pulverizer, and then sieve it through a 20-60 mesh sieve to obtain corn straw powder; air-dry the walnut shell under natural conditions, crush the dried material in a pulverizer, and then sieve it through a 20-60 mesh sieve to obtain walnut shell powder.

[0060] (2) Place the corn straw powder and walnut shell powder separately in an atmosphere furnace. The furnace provides an oxygen-limited environment by introducing high-purity nitrogen. Set the heating rate of the furnace at 5-10 °C / min, maintain it at 400-550 °C for 2-3 h, and then naturally cool it to room temperature. Then grind the obtained corn straw biochar and walnut shell biochar and sieve them through a 100-120 mesh sieve.

[0061] (3) Uniformly mix the corn straw biochar and walnut shell biochar in a mass ratio of 1:1, then place them in an oven and dry them at 60-65 °C to constant weight. After cooling to room temperature, obtain the passivator complex.

[0062] (4) Spread the passivator complex into the soil at a dosage of 300 kg / mu, and then plow the soil to evenly incorporate the passivator complex into the soil. After natural stabilization for 6 months, sample and analyze the bioavailable concentration of heavy metals.

[0063] Example 7

[0064] (1) Air-dry the walnut shells under natural conditions, crush the dried material in a pulverizer, and then sieve through a 20 - 60 mesh sieve to obtain walnut shell powder.

[0065] (2) Place the walnut shell powder in an atmosphere furnace. The furnace provides an oxygen-limited environment by introducing high-purity nitrogen. Set the heating rate of the furnace at 5 - 10 °C / min, hold at 400 - 550 °C for 2 - 3 h, and then naturally cool to room temperature. Then grind the obtained walnut shell biochar and sieve through a 100 - 120 mesh sieve.

[0066] (3) Weigh a certain amount of walnut shell biochar, wash it repeatedly with clear water for more than 3 times, air-dry it naturally, and then evenly mix it with hydroxyapatite in a mass ratio of 1:1. After that, place it in an oven at 60 - 65 °C and dry to a constant weight. After cooling to room temperature, obtain the passivator complex.

[0067] (4) Spread the passivator complex into the soil at a dosage of 100 kg / mu each time, and then plow the soil to evenly incorporate the passivator complex into the soil. Do this continuously for 6 times. After natural stabilization for 6 months, sample and analyze the bioavailable concentration of heavy metals.

[0068] Example 8

[0069] (1) Air-dry the walnut shells under natural conditions, crush the dried material in a pulverizer, and then sieve through a 20 - 60 mesh sieve to obtain walnut shell powder.

[0070] (2) Place the walnut shell powder in an atmosphere furnace. The furnace provides an oxygen-limited environment by introducing high-purity nitrogen. Set the heating rate of the furnace at 5 - 10 °C / min, hold at 400 - 550 °C for 2 - 3 h, and then naturally cool to room temperature. Then grind the obtained walnut shell biochar and sieve through a 100 - 120 mesh sieve.

[0071] (3) Weigh a certain amount of walnut shell biochar, wash it repeatedly with clear water for more than 3 times, air-dry it naturally, and then evenly mix it with hydroxyapatite in a mass ratio of 1:1. After that, place it in an oven at 60 - 65 °C and dry to a constant weight. After cooling to room temperature, obtain the passivator complex.

[0072] (4) Spread the passivator complex into the soil at a dosage of 100 kg / mu, and then plow the soil to evenly incorporate the passivator complex into the soil. After natural stabilization for 6 months, sample and analyze the bioavailable concentration of heavy metals.

[0073] Example 9

[0074] (1) Air-dry walnut shells under natural conditions, crush the dried material in a pulverizer, and then sieve it through a 20-60 mesh sieve to obtain walnut shell powder.

[0075] (2) Place the walnut shell powder in an atmosphere furnace. The furnace provides an oxygen-limited environment by introducing high-purity nitrogen. Set the heating rate of the furnace at 5-10 °C / min, hold at 400-550 °C for 2-3 h, and then naturally cool to room temperature. Then grind the obtained walnut shell biochar and sieve it through a 100-120 mesh sieve.

[0076] (3) Weigh a certain amount of walnut shell biochar, wash it repeatedly with clear water for more than 3 times, air-dry it naturally, and then uniformly mix it with hydroxyapatite in a mass ratio of 1:1. After that, put it in an oven and dry it at 60-65 °C to constant weight. After cooling to room temperature, obtain the passivator compound.

[0077] (4) Spread the passivator compound into the soil at a dosage of 300 kg / mu, and then plow the soil to uniformly turn the passivator compound into the soil. After natural stabilization for 6 months, take samples to analyze the bioavailable concentration of heavy metals.

[0078] Example 10

[0079] (1) Air-dry corn straw under natural conditions, crush the dried material in a pulverizer, and then sieve it through a 20-60 mesh sieve to obtain corn straw powder.

[0080] (2) Place the corn straw powder in an atmosphere furnace. The furnace provides an oxygen-limited environment by introducing high-purity nitrogen. Set the heating rate of the furnace at 5-10 °C / min, hold at 400-550 °C for 2-3 h, and then naturally cool to room temperature. Then grind the obtained corn straw biochar and sieve it through a 100-120 mesh sieve.

[0081] (3) Weigh a certain amount of corn straw biochar, wash it repeatedly with clear water for more than 3 times, air-dry it naturally, and then uniformly mix it with sepiolite in a mass ratio of 1:1. After that, put it in an oven and dry it at 60-65 °C to constant weight. After cooling to room temperature, obtain the passivator compound.

[0082] (4) Spread the passivator compound into the soil at a dosage of 100 kg / mu each time, and then plow the soil to uniformly turn the passivator compound into the soil. Spread it continuously for 6 times. After natural stabilization for 6 months, take samples to analyze the bioavailable concentration of heavy metals.

[0083] Example 11

[0084] (1) Air-dry the corn straw under natural conditions, crush the dried material in a pulverizer, and then sieve it through a 20-60 mesh sieve to obtain corn straw powder;

[0085] (2) Place the corn straw powder in an atmosphere furnace. The furnace provides an oxygen-limited environment by introducing high-purity nitrogen; set the heating rate of the furnace at 5-10 °C / min, hold it at 400-550 °C for 2-3 h, and then naturally cool it to room temperature; then grind the obtained corn straw biochar and sieve it through a 100-120 mesh sieve;

[0086] (3) Weigh a certain amount of corn straw biochar, wash it repeatedly with clear water for more than 3 times, air-dry it naturally, and then uniformly mix it with sepiolite in a mass ratio of 1:1. After that, put it into an oven and dry it at 60-65 °C to constant weight. After cooling to room temperature, obtain the passivator compound.

[0087] (4) Spread the passivator compound into the soil at a dosage of 100 kg / mu, and then plow it to evenly turn the passivator compound into the soil. After natural stabilization for 6 months, take samples to analyze the bioavailable concentration of heavy metals.

[0088] Example 12

[0089] (1) Air-dry the corn straw under natural conditions, crush the dried material in a pulverizer, and then sieve it through a 20-60 mesh sieve to obtain corn straw powder;

[0090] (2) Place the corn straw powder in an atmosphere furnace. The furnace provides an oxygen-limited environment by introducing high-purity nitrogen; set the heating rate of the furnace at 5-10 °C / min, hold it at 400-550 °C for 2-3 h, and then naturally cool it to room temperature; then grind the obtained corn straw biochar and sieve it through a 100-120 mesh sieve;

[0091] (3) Weigh a certain amount of corn straw biochar, wash it repeatedly with clear water for more than 3 times, air-dry it naturally, and then uniformly mix it with sepiolite in a mass ratio of 1:1. After that, put it into an oven and dry it at 60-65 °C to constant weight. After cooling to room temperature, obtain the passivator compound.

[0092] (4) Spread the passivator compound into the soil at a dosage of 300 kg / mu, and then plow it to evenly turn the passivator compound into the soil. After natural stabilization for 6 months, take samples to analyze the bioavailable concentration of heavy metals.

[0093] Example 13

[0094] (1) Air-dry the rice straw under natural conditions, crush the dried material in a pulverizer, and then sieve it through a 20-60 mesh sieve to obtain rice straw powder;

[0095] (2) Place the rice straw powder in an atmosphere furnace, and the furnace provides an oxygen-limited environment by introducing high-purity nitrogen; set the heating rate of the furnace at 5-10 °C / min, hold at 400-550 °C for 2-3 h, and then cool naturally to room temperature; then grind the obtained rice straw biochar and pass through a 100-120 mesh sieve;

[0096] (3) Weigh a certain amount of rice straw biochar, wash it repeatedly with clear water more than 3 times, air-dry it naturally, and then uniformly mix it with sepiolite in a mass ratio of 1:1. After that, put it into an oven and dry it at 60-65 °C to constant weight. After cooling to room temperature, a passivator compound is obtained.

[0097] (4) Spread the passivator compound into the soil, with a dosage of 100 kg / mu each time, and then plow the soil to evenly incorporate the passivator compound into the soil. Spread it continuously 6 times. After natural stabilization for 6 months, take samples to analyze the bioavailable concentration of heavy metals.

[0098] Example 14

[0099] (1) Air-dry the rice straw under natural conditions, crush the dried material in a crusher, and then pass through a 20-60 mesh sieve to obtain rice straw powder;

[0100] (2) Place the rice straw powder in an atmosphere furnace, and the furnace provides an oxygen-limited environment by introducing high-purity nitrogen; set the heating rate of the furnace at 5-10 °C / min, hold at 400-550 °C for 2-3 h, and then cool naturally to room temperature; then grind the obtained rice straw biochar and pass through a 100-120 mesh sieve;

[0101] (3) Weigh a certain amount of rice straw biochar, wash it repeatedly with clear water more than 3 times, air-dry it naturally, and then uniformly mix it with sepiolite in a mass ratio of 1:1. After that, put it into an oven and dry it at 60-65 °C to constant weight. After cooling to room temperature, a passivator compound is obtained.

[0102] (4) Spread the passivator compound into the soil, with a dosage of 100 kg / mu, and then plow the soil to evenly incorporate the passivator compound into the soil. After natural stabilization for 6 months, take samples to analyze the bioavailable concentration of heavy metals.

[0103] Example 15

[0104] (1) Air-dry the rice straw under natural conditions, crush the dried material in a crusher, and then pass through a 20-60 mesh sieve to obtain rice straw powder;

[0105] (2) Place the rice straw powder in an atmosphere furnace, and the furnace provides an oxygen-limited environment by introducing high-purity nitrogen; set the heating rate of the furnace at 5-10 °C / min, hold at 400-550 °C for 2-3 h, and then cool naturally to room temperature; then grind the obtained rice straw biochar and pass it through a 100-120 mesh sieve;

[0106] (3) Weigh a certain amount of rice straw biochar, wash it repeatedly with clear water for more than 3 times, and after natural air drying, uniformly mix it with sepiolite in a mass ratio of 1:1, and then put it into an oven and dry at 60-65 °C until constant weight, and obtain the passivator compound after cooling to room temperature.

[0107] (4) Spread the passivator compound into the soil at a dosage of 300 kg / mu, and carry out plowing to evenly turn the passivator compound into the soil. After natural stabilization for 6 months, take samples to analyze the bioavailable concentration of heavy metals.

[0108] The soil pH distribution under different passivator compound treatments is shown in Figure 1 ;

[0109] Figure 1 In it, CK is the control group;

[0110] S5BI5-1 is a compound of sepiolite and corn straw biochar with a mass ratio of 1:1 and an addition amount of 100 kg / mu;

[0111] S5BI5-3 is a compound of sepiolite and corn straw biochar with a mass ratio of 1:1 and an addition amount of 300 kg / mu;

[0112] S5BI5-6 is a compound of sepiolite and corn straw biochar with a mass ratio of 1:1 and an addition amount of 600 kg / mu.

[0113] S5BⅡ5-1 is a compound of sepiolite and rice straw biochar with a mass ratio of 1:1 and an addition amount of 100 kg / mu;

[0114] S5BⅡ5-3 is a compound of sepiolite and rice straw biochar with a mass ratio of 1:1 and an addition amount of 300 kg / mu;

[0115] S5BⅡ5-6 is a compound of sepiolite and rice straw biochar with a mass ratio of 1:1 and an addition amount of 600 kg / mu;

[0116] qjym-1 is a compound of hydroxyapatite and corn straw biochar with a mass ratio of 1:1 and an addition amount of 100 kg / mu;

[0117] qjym-3 is a compound of hydroxyapatite and corn straw biochar with a mass ratio of 1:1 and an addition amount of 300 kg / mu;

[0118] Qjym-6 is a compound mixture of hydroxyapatite and corn straw biochar with a mass ratio of 1:1 and an application rate of 600 kg / mu;

[0119] Qjht-1 is a compound mixture of hydroxyapatite and walnut shell biochar with a mass ratio of 1:1 and an application rate of 100 kg / mu;

[0120] Qjht-3 is a compound mixture of hydroxyapatite and walnut shell biochar with a mass ratio of 1:1 and an application rate of 300 kg / mu;

[0121] Qjht-6 is a compound mixture of hydroxyapatite and walnut shell biochar with a mass ratio of 1:1 and an application rate of 600 kg / mu;

[0122] Ymht-1 is a compound mixture of corn straw biochar and walnut shell biochar with a mass ratio of 1:1 and an application rate of 100 kg / mu;

[0123] Ymht-3 is a compound mixture of corn straw biochar and walnut shell biochar with a mass ratio of 1:1 and an application rate of 300 kg / mu;

[0124] Ymht-6 is a compound mixture of corn straw biochar and walnut shell biochar with a mass ratio of 1:1 and an application rate of 600 kg / mu;

[0125] From the results, it can be seen that after adding Qjym, Qjht, and Ymht, the soil pH increased significantly compared with the control group (CK), and the concentrations of bio-available Cr, Cd, and Pb in the soil gradually decreased, as shown in Figure 2 , 6 , and 7.

[0126] The concentrations of bio-available Cr, Cu, Zn, As, Cd, and Pb in the soil treated with different passivator compound mixtures are shown in Figure 2-7 . The concentrations of bio-available Cr, Cu, Zn, Cd, and Pb in the soil treated with the Qjym-6 treatment group are the lowest and are all lower than those of the control group, and the passivation effect is the best; the concentration of bio-available As in the soil treated with the Qjym-6 treatment group is less than that of the control group. It shows that the Qjym-6 treatment group has a passivation effect on heavy metals in the heavy metal composite polluted soil, and the passivation effect on most heavy metals is the best.

[0127] The above embodiments are provided to better understand the present invention further, and are not limited to the best implementation mode, and do not constitute a limitation to the content and protection scope of the present invention. Any product that is the same as or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other existing technologies falls within the protection scope of the present invention.

Claims

1. A method for remediating soil contaminated by heavy metals in a traditional zinc smelting site by using a passivating agent compound, characterized in that: The passivation agent compound is spread into the soil of the traditional zinc smelting site at a dosage of 100-600 kg / mu, and the soil is tilled to evenly turn the passivation agent compound into the soil. After stabilization for 6-12 months, samples are taken for analysis of heavy metal concentrations. The passivator compound comprises one or more of biochar material and natural mineralized material, and the added amount mass ratio of the two is 1 to 3:1; the natural mineralized material is selected from one or more of sepiolite and hydroxyapatite.

2. According to claim 1, a method for remediating soil contaminated by heavy metals in a traditional zinc smelting site using a passivating agent, characterized in that: The biochar material includes one or more of rice straw biochar, corn straw biochar and walnut shell biochar.

3. According to claim 2, a method for remediating soil contaminated by heavy metals in a traditional zinc smelting site using a passivating agent, characterized in that: When the biochar material is two of rice straw biochar, corn straw biochar and walnut shell biochar, the added amount satisfies a mass ratio of 1-5:1-5.

4. According to claim 2, a method for remediating soil contaminated by heavy metals in a traditional zinc smelting site using a passivating agent, characterized in that: When the biochar material is rice straw biochar, corn straw biochar and walnut shell biochar, the added amount satisfies the mass ratio of 1-5:1-5:1-5.

5. According to claim 1, a method for remediating soil contaminated by heavy metals in a traditional zinc smelting site using a passivating agent, characterized in that: The passivating agent compound is sprinkled 6 to 10 times.

6. According to claim 1, a method for remediating soil contaminated by heavy metals in a traditional zinc smelting site using a passivating agent, characterized in that: The tillage depth is 15 to 40 cm.

7. The method for remediating soil contaminated by heavy metals in a traditional zinc smelting site by using a passivating agent according to claim 1, characterized in that: The preparation method of the passivator compound is: (1) air-drying the biochar material under natural conditions, crushing it, and then sieving it to obtain biochar material powder; (2) placing the biochar material powder in an atmosphere furnace, and introducing high-purity nitrogen into the furnace to provide an oxygen-limited environment; setting the furnace to a heating rate of 5-10°C / min, maintaining at 400-550°C for 2-3h, and then naturally cooling to room temperature; then grinding and sieving the obtained biochar material; (3) The biochar material obtained in step (2) is repeatedly washed with clean water, naturally air-dried, and then evenly mixed with natural minerals, and then placed in an oven at 60-65° C. to dry to constant weight, and then cooled to room temperature to obtain a passivating agent compound.

8. The method for remediating soil contaminated by heavy metals in a traditional zinc smelting site by using a passivating agent according to claim 7, characterized in that: In step (1), the sieving is through a 20-60 mesh sieve.

9. The method for remediating soil contaminated by heavy metals in a traditional zinc smelting site by using a passivating agent according to claim 7, characterized in that: In step (2), the sieving is through a 100-120 mesh sieve.

10. The method for remediating soil contaminated by heavy metals in a traditional zinc smelting site by using a passivating agent according to claim 7, characterized in that: In step (1), the biochar material is selected from one or more of corn straw, rice straw and walnut shell.

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