Tailings-loaded biochar soil remediation agent and preparation method thereof

Abstract

The application discloses a tailing-loaded biochar soil remediation agent and a preparation method thereof, and the tailing and food waste are uniformly mixed, ball-milled, and then treated by water bath with the addition of alkali liquor, and after standing and drying, the mixture is calcined by temperature rising and naturally cooled to room temperature. The application realizes the transfer of the carbon source in solid waste to the infertile soil, solves the problems of heavy metal pollution in the tailing and difficult treatment of the food waste, and combines the tailing and the food waste to prepare a tailing biochar composite material, so that the soil carbon storage is increased and the harm of the heavy metal in the soil is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of carbon transfer, and more particularly relates to a tailing bio-carbon composite material and a preparation method thereof. BACKGROUND

[0002] In recent years, with the rapid development of economy, the utilization and development of resources in China, industrial solid waste and municipal solid waste also increase, and solid waste will cause different degrees of harm to the atmosphere, water and soil due to its complex composition, high heavy metal content, excessive acidity and alkalinity. Therefore, how to deal with the increasing solid waste is a problem that needs to be solved by human beings at present.

[0003] Tailing is the main part of industrial waste, and the annual output accounts for about one third of the total amount of industrial solid waste, which is more than the output of other solid waste such as coal gangue and fly ash. A large amount of tailings cannot be treated and accumulated in the mining area, which occupies land resources, and due to technical reasons, a large amount of useful metals remain in the tailings and are not utilized, and more importantly, the tailings contain a large amount of heavy metal elements, and the accumulated tailings are easy to cause pollution to the surrounding environment. The simplest method for treating tailings is to add a solidifying agent to solidify the heavy metals in the tailings. Chinese patent (CN101912865A) discloses a dry stacking method for solidifying and treating tailings without tailings pond. The patent uses a dry stacking method to treat tailings, which achieves the effect of solidifying heavy metals, but does not solve the problem of tailings accumulation, and the solidifying agent needs to be added during the treatment process, which increases the cost. Compared with the method of adding a solidifying agent, it is more practical to use tailings to make building materials and other materials, which not only solidifies the heavy metals in the tailings, but also achieves good economic benefits. Chinese patent (CN103274669A) discloses a copper-molybdenum tailing dry hanging hollow ceramic plate and a preparation method thereof, which uses tailings to make silicate bricks, not only to prepare products with economic benefits, but also to solidify heavy metals in the high-temperature process. However, this method has composition requirements for tailings, and high-temperature sintering will waste energy, and other building materials also have the same problem. Solidifying heavy metals in tailings and improving its physicochemical properties not only consider the effect, but also cannot ignore the cost problem.

[0004] Food waste as urban solid waste, a large accumulation will produce odor, carbon dioxide and methane, and it contains a large amount of organic matter, easy to spoil, produce bacteria. Therefore, kitchen waste will not only cause environmental pollution, but also affect human health. The main method of food waste treatment is landfill, incineration and composting. Chinese patent (CN105478441A) discloses a "food waste treatment equipment", the equipment includes sedimentation tank, oil-water separation tank, grinding cavity and dry-wet separation device for multi-step treatment of food waste. Although the food waste is treated before landfill, the risk to the environment is reduced, but the instrument is complex, and the cost is too high. Chinese patent (CN211247719U) discloses a "treatment system for multiple solid wastes in a circular industrial park", food waste, feces and other solid wastes are used for power generation. Although good economic benefits can be achieved, and the environment is less polluted, food waste is a low-calorific-value urban solid waste, which needs to be treated before combustion.

[0005] The treatment method for the two kinds of solid waste is still limited to the solution and utilization of single solid waste, and the treatment method has high cost and poor economic benefit. Microwave heating can quickly prepare a soil repair agent with high carbon content, and has the advantages of low energy consumption, fast preparation speed and the like, which has practical significance for preparing this type of material. SUMMARY

[0006] The purpose of the present application is to realize the transfer of carbon source in solid waste to barren soil, and to solve the problems of heavy metal pollution in tailings and difficult treatment of food waste. The tailings-biochar composite material is prepared by combining the two, which increases the soil carbon storage and reduces the harm of heavy metals in soil. The tailings-biochar organic-inorganic composite is successfully prepared by mixing high heavy metal content tailings (molybdenum tailings, iron tailings, lead tailings, etc.) with food waste (oil-water separation, drying treatment) and heating. The waste carbon source is transferred to the material, a small amount of silicate form iron is reduced to iron oxide, and biochar is loaded on the surface. Si atoms and carbon atoms form covalent bonds. Heavy metal oxides are solidified in the form of silicates inside the tailings, and biochar adsorbs water-soluble and exchangeable heavy metal ions in the tailings. The material can be widely used in heavy metal pollution mining areas and related fields (such as a new type of soil repair agent for plant growth), increase the soil carbon content, and reduce the soil heavy metal availability.

[0007] The technical purpose of the present application is realized by the following technical scheme.

[0008] A tailings loaded biochar soil repair agent and a preparation method thereof, the tailings and food waste are mixed uniformly, then ball milled, alkali solution is added to the mixture after ball milling for water bath treatment, and after standing and drying, the mixture is heated and calcined, and naturally cooled to room temperature, wherein:

[0009] The mass ratio of the tailings and the food waste is (3-5):1, preferably 5:1;

[0010] When the ball milling is performed, the mass ratio of the ball to the material is (2-3):1, preferably 3:1, the rotation speed of the ball milling is 500-800 rpm, and the grinding time is 30-60 min;

[0011] The alkali solution is an aqueous solution of sodium hydroxide or potassium hydroxide with a concentration of 3-5 mol / L, the temperature of the water bath treatment is 80-90 degrees Celsius, the time of the water bath treatment is 1-2 hours, and the standing time at room temperature of 20-30 degrees Celsius is 20-24 hours;

[0012] In the process of the temperature rising calcination, a tube furnace or a microwave heater is used, and inert protective gas is introduced to ensure that the reaction is performed in an oxygen-free condition, the temperature of the heat preservation calcination is 450-750 degrees Celsius, and the time is 1-3 hours.

[0013] In the technical scheme of the present application, the tailings are molybdenum tailings, iron tailings or lead tailings, the main mineral phases are quartz, chlorite, cordierite and amphibole, the sum of the contents of the main phases chlorite and amphibole is more than 20%, and the content of quartz is more than 70%.

[0014] In the technical scheme of the present application, the tailings are sieved through a 200-300 mesh sieve.

[0015] In the technical scheme of the present application, the food waste is subjected to oil-water separation, and 60- parts by mass of the food waste subjected to the oil-water separation is mixed with 15-20 parts by mass of water and 15-20 parts by mass of a hydroxide (such as potassium hydroxide or sodium hydroxide) to be stirred and stood, the stirring time is 1-2 hours, the stirring speed is 100-200 revolutions per minute, the standing time is 10-12 hours, and the standing temperature is 20-30 degrees Celsius.

[0016] In the technical scheme of the present application, after standing, the mixture is placed in an oven for drying at a temperature of 50-60 degrees Celsius for 40-48 hours.

[0017] In the technical scheme of the present application, the temperature is raised from room temperature of 20-25 degrees Celsius at a rate of 5-10 degrees Celsius per minute.

[0018] In the technical scheme of the present application, the temperature of the heat preservation calcination is 450-650 degrees Celsius, and the time is 2-3 hours.

[0019] In the technical scheme of the present application, the inert protective gas is nitrogen, helium or argon.

[0020] In the technical scheme of the present application, the power of the microwave heater is 1600 w.

[0021] The application utilizes solid waste to prepare a new soil remediation agent, which is applied to acid mine area soil, provides organic carbon for plant growth, reduces the toxicity of heavy metals in the surface soil, and ensures the survival of plants by covering the contaminated soil surface with the soil remediation agent as soil cover; in terms of composition, at present, food waste and tailings are the main sources of solid waste, which cause great harm to the surrounding environment, and the food waste and tailings can introduce rich trace elements and provide the required elements for plant microorganisms; meanwhile, quartz and silicates as the main components of tailings can become the parent material of soil; the biomass charcoal formed by food waste can repair heavy metals in tailings and solidify heavy metal elements; the application prepares a new soil remediation agent, controls the reaction time, temperature and ratio to make the material after heating form an organic-inorganic composite, and the repaired soil has low soil bulk density and high water and fertilizer retention capacity; the tailings and the biomass charcoal are combined to repair heavy metals, improve the soil environment and improve the overall physicochemical properties of the improved soil.

[0022] The application first prepares two main sources of solid waste into a new soil remediation agent which is beneficial to the environment, has high practical value and economic benefits, and solves the problems of difficult treatment and utilization of tailings and food waste; the new soil remediation agent prepared by the application forms an organic-inorganic composite of tailings and biomass charcoal, reduces the soil bulk density, enhances the water and fertilizer retention capacity of the soil, improves the soil environment and adjusts the pH value of the soil; the application prepares biomass charcoal material under low-temperature anaerobic conditions, the biomass charcoal has the characteristics of large porosity and specific surface area, rich surface charge and chemical functional groups, strong ion exchange capacity and the like, has strong adsorption capacity for heavy metal ions, and can effectively reduce the availability of heavy metals in tailings; the tailings and food waste contain rich trace elements, and the generated biomass charcoal can provide carbon source for the soil, accelerate the mineralization process of soil organic matter, and achieve the effect of carbon fixation and carbon supplementation; the process of the application is simple, low in cost and easy to operate, and is easy to realize large-scale production, thereby widening the comprehensive utilization way of tailings and food waste. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is the X-Ray spectrum of tailings used in the embodiment of the application.

[0024] Figure 2 It is the scanning electron microscope photos and element EDS analysis result graphs of different tailings-biomass charcoal composite materials (TB, MTB1, MTB2, MTB3, MTB4) in the embodiment of the application.

[0025] Figure 3 It is the Raman spectrum test graphs of different tailings-biomass charcoal composite materials (TB, MTB1, MTB2, MTB3, MTB4) in the embodiment of the application.

[0026] Figure 4is the soil organic carbon change column chart of the soil added with different tailing biochar composite materials (CK, TB, MTB1, MTB2, MTB3, MTB4) in the embodiment of the application.

[0027] Figure 5 is the high active organic carbon, medium active organic carbon, low active organic carbon in the active organic carbon, and the proportion of the high active organic carbon, medium active organic carbon, low active organic carbon in the active organic carbon (b) content change column chart of the tailing biochar composite material (a) added in the embodiment of the application.

[0028] Figure 6 is the soil dissolved organic carbon content change column chart of the soil added with different tailing biochar composite materials (CK, TB, MTB1, MTB2, MTB3, MTB4) in the embodiment of the application. DETAILED DESCRIPTION

[0029] In order to better understand the application, the content of the application will be further described below in combination with the embodiments, but the content contained in the application is not limited to the following embodiments.

[0030] In the following implementation, the tailings come from Chengde, Hebei, and the chemical composition analysis is shown in the following table.

[0031]

[0032] The tailing mineral phase is analyzed, and the X-ray diffraction pattern is shown in Figure 1 The mineral phase identification table shows that the main mineral phases are quartz, chlorite, cordierite, and amphibole. Combined with the tailing composition table (Table 1) and the tailing X-ray diffraction phase analysis Figure 1 ), it is preliminarily judged that the sum of the main phases chlorite and amphibole in the tailings is more than 20%, and the content of quartz is more than 70%.

[0033] The collected tailings are in powder form, but the particle size distribution of the tailings is not uniform, and they need to be sieved to obtain the appropriate use particle size. The collected tailing samples are dried in an oven for 24 hours before use to remove free water in the tailings, and then the tailings are sieved through a 200 mesh sieve for standby.

[0034] 16.8g of KOH was weighed, and then 100mL of deionized water was poured into a beaker using a graduated cylinder. Stirring was performed using a magnetic stirrer, the stirring speed was 500rpm, the stirring time was 30min, finally the solution was clear and the temperature did not change, and a 3mol / L KOH solution was successfully prepared.

[0035] The food waste is added to the feed inlet of the oil-water separator, 60 parts by weight of food waste residue is weighed out from the discharge outlet, and is mixed with 20 parts by weight of water and 20 parts by weight of potassium hydroxide and stirred for 1 h, and is allowed to stand for 12 h. The food waste after standing is dried for standby. In the process of temperature rising calcination and heat preservation, a tubular furnace or a microwave heater is used, and nitrogen is introduced to ensure that the reaction is carried out in an oxygen-free condition.

[0036] In the embodiment of the present application, considering the role of carbon in food waste and the influence of carbon transfer on soil, flour is used to replace food waste for comparison, and the preparation process is as follows: tailings and flour are uniformly mixed in a mass ratio of 5:1 and placed in a ball mill tank, the ball-to-material mass ratio in the ball mill tank is 3:1, and the ball mill is used at a rotating speed of 800 rpm. The grinding time is 30 min. After the sample is taken out, 50 ml of deionized water is added, and the sample is heated in a water bath at 85°C for 1 h, and then placed in an oven for 48 h. After drying, the sample is taken out. The material is calcined at 650°C for 2 h in a tube furnace (temperature rising from room temperature 20-25°C at a rate of 10°C / min), and the sample is obtained after cooling, washed with deionized water until the pH value does not change, and the dried sample is crushed through a 20-mesh sieve for standby, and the sample is named as TB.

[0037] In the embodiment of the present application, the preparation of tailings loaded biochar soil remediation agent is as follows:

[0038] The tailings and food waste are uniformly mixed in a mass ratio of 5:1 and placed in a ball mill tank, the ball-to-material mass ratio in the ball mill tank is 3:1, the ball mill is used at a rotating speed of 800 rpm, and the grinding time is 30 min. After the sample is taken out, 50 ml of 3 mol / L KOH solution is added, heated in a water bath at 85°C for 1 h, and allowed to stand at room temperature for 24 h, and then placed in an oven for 48 h. After drying, the sample is taken out. The material is calcined at 450°C, 550°C, 650°C and 750°C for 2 h in a tube furnace (temperature rising from room temperature 20-25°C at a rate of 10°C / min), and the sample is obtained after cooling, washed with deionized water until the pH value does not change, and the dried sample is crushed through a 20-mesh sieve for standby, and the sample is named as MTB1, MTB2, MTB3 and MTB4, respectively.

[0039] The tailings loaded biochar soil remediation agent prepared from food waste and tailings of the present application transfers the waste carbon source into the material, and the surface carbon source of the material is analyzed, and the basic properties are shown in the following table.

[0040] Variable pH C％ H％ N％ Yield % Carbon fixation rate % TB 8.12 3.31 0.12 0 88 2.91 MTB1 8.55 5.05 0.57 0 90 4.54 MTB2 8.72 4.01 0.48 0 88 3.52 MTB3 8.6 4.61 0.52 0 87 4.01 MTB4 9.1 0.39 0.61 0 85 0.33

[0041] As shown in the above table, the carbon element content of tailings loaded biochar soil remediation agent prepared under different conditions is different, and the carbon element content of TB, MTB1, MTB2, MTB3 and MTB4 is 3.31, 5.05, 4.01, 4.61 and 0.39.

[0042] As shown in Figure 2 , the scanning morphology of different tailings loaded biochar soil remediation agent (i.e. tailings biochar composite materials TB, MTB1, MTB2, MTB3 and MTB4) is (a-e) in turn; (f-i) is the C, Fe and Si element mapping of MTB3. In the figure, the surface of the unmodified tailings biochar composite material TB is smoother than that of the alkali modified tailings biochar composite material (MTB1, MTB2, MTB3 and MTB4), and the surface of the alkali modified material is rougher. Therefore, more adsorption sites can be provided for the surface and interior of the material, which can be beneficial to the adsorption of heavy metals. In the mapping of the composite material MTB3, it is found that Fe and Si elements are uniformly distributed on the surface, which indicates that the main element composition of the modified material is still mainly quartz, and the uniform distribution of Fe element on the surface means that iron oxides can better contact the surface heavy metals, thereby solidifying the heavy metals on the surface. The distribution of C element in the figure is consistent with the distribution of small particles on the surface in f, which indicates that the biochar on the surface of the material is in the form of particles loaded on the surface.

[0043] As shown in Figure 3 , (a) is the Raman spectrum of different tailings biochar composite materials, (b) is the Raman spectrum of TB, (c) is the Raman spectrum of MTB1, (d) is the Raman spectrum of MTB2, (e) is the Raman spectrum of MTB3, and (f) is the Raman spectrum of MTB4. The specific data is shown in the table below. Raman spectrum detection of the material is carried out to study the influence of different pyrolysis temperatures on carbon distribution. There are two characteristic peaks in the spectrum band, representing the D peak of disordered structure and the G peak of graphitization structure. D / I G represents the order and integrity of the carbon material studied, and the larger the ratio, the higher the degree of defects. With the increase of temperature, the ratio of I D / I G increases from 0.86 at 450℃ to 1.08 at 650℃, indicating that the surface biochar defects increase with the increase of temperature, and the ratio of I D / I G of the unmodified tailings biochar is significantly smaller than that of the modified material, indicating that the degree of disorder of the modified material increases. The increase of the degree of disorder of biochar provides more adsorption sites for heavy metal Cd. And no D peak and G peak are observed for MTB4 prepared at 750℃, indicating that the loss on ignition of biochar is serious at high temperature, and the biochar volatilizes with pyrolysis, and the content of biochar on the surface of MTB4 is greatly reduced. With the increase of temperature, Sp2 / Sp 3 The ratio increased and the content of unsaturated carbon increased. It was speculated that the alkyl group was pyrolyzed and disappeared with the increase of temperature, while the content of unsaturated carbon containing oxygen functional groups gradually increased, but the unsaturated carbon disappeared at 750 degrees.

[0044] Samples I D / I G ]]> SP 2 peak area of the carbon of the type <![CDATA[SP 3 Peak area of ​​type carbon TB 0.55 86.89 13.11 MTB1 0.86 60.33 39.67 MTB2 0.87 62.91 37.09 MTB3 1.08 72.44 27.56 MTB4 n.d n.d n.d

[0045] The soil samples (labeled as CK) in the mining area were mixed with the tailings biochar composite materials prepared in the above examples (as soil repair agents), and the addition amount of the tailings biochar composite materials was 8% of the mass of the soil samples. The soil organic carbon content, soil bulk density, field moisture capacity, and whether the heavy metal content exceeded the standard were detected.

[0046] 1. The SOC content changes of the soil added with different tailings biochar composite materials, as shown in Figure 4 After adding the tailings biochar composite materials, the soil organic carbon content of each treatment group of TB, MTB1, MTB2, and MTB3 was higher than that of CK (10.3 g / kg), and the soil organic carbon content of TB, MTB1, MTB2, and MTB3 was increased by 14.49%, 1.88%, 47.47%, and 54.28% compared with CK.

[0047] 2. The active organic carbon in the soil is the most active organic carbon composition in the soil, which is of great significance to plant growth and environmental evaluation, Figure 5 The influence of tailings biochar composite materials on the content of soil active organic carbon can be seen from the table. It can be seen that the application of MTB3 has the greatest influence on the content of soil active organic carbon, and the total content of soil active organic carbon is 0.604 g / kg. MTB3 has the highest influence on the content of soil active organic carbon, and provides more soil active organic carbon to the soil. Compared with the control group CK, the content of soil active organic carbon of TB, MTB1, MTB2, and MTB4 is 0.592, 0.492, 0.528, and 0.424 mg / kg, respectively. The content of low active organic carbon in the soil of MTB2 and MTB3 is the highest, accounting for 60% and 55% of the total active organic carbon content. Secondly, the content of active organic carbon in the soil of MTB1 is the highest, accounting for 50% of the total active organic carbon content. The content of high active organic carbon in the soil of MTB3 is the highest, accounting for 13% of the total soil active organic carbon.

[0048] 3. The influence of adding different tailings biochar composite materials to the same soil on the dissolved organic carbon, as shown in Figure 6As shown, the water-soluble organic carbon content in the soil changed with the addition of different tailings biochar composite materials. The dissolved organic carbon content of different treatment groups (CK, TB, MTB1, MTB2, MTB3, and MTB4) was 158.01, 172.59, 184.78, 222.67, 225.99, and 147.03 mg / kg, respectively. The dissolved organic carbon content of TB and MTB4 compared with CK had no significant change, and MTB1 increased by 16.94% (P < 0.05) compared with CK. While MTB2 and MTB3 increased by 40.92% and 43.02% compared with CK. The dissolved organic carbon content of MTB4 compared with CK decreased by 6.94%.

[0049] 4. The rye was planted in the tailings biochar composite material and soil mixed soil to test the effect of plant carbon fixation capacity. According to the photosynthesis chemical equation of grass (6CO2+6H2O------C6H 12 O6+6O2), 1.63 kg of CO2 can be fixed for every 1 kg of dry matter produced by vegetation, and 0.27 kg of carbon is contained in 1 kg of CO2. The carbon content in dry matter is denoted as P. Therefore, the amount of carbon fixed by plants (plant carbon fixation capacity calculation formula) can be calculated by NPP:

[0050] WCO2=NPP / P×1.63

[0051] WC=WCO2×0.27

[0052] In the formula, WCO2- the amount of CO2 fixed by vegetation per unit area in a certain period of time, unit g.m -2

[0053] WC- the amount of carbon fixed by vegetation per unit area in a certain period of time, unit g.m -2

[0054] NPP- the net primary productivity of vegetation per unit area in a certain period of time, unit g.m -2

[0055] The net primary productivity (NPP) of vegetation in the soil after adding different tailings biochar is shown in the following table. The net primary productivity of rye in the soil added with MTB3 reached 153.22 g / m 2 , which increased by 229.57% compared with the untreated soil. The net primary productivity of rye in the soil added with MTB4 was only 32.65 g / m 2 , which was lower than the net primary productivity of rye in the untreated soil, and decreased by 29.76% compared with the net primary productivity of rye in the untreated soil.

[0056] Samples [NPP (g / m 2 )]]> Fixed CO2(g / m 2 )]]> Carbon sequestration amount (g / m 2 )]]> CK 47.59 184.95 49.93 TB 63.45 242.17 65.38 MTB1 66.96 384.47 103.80 MTB2 112.92 608.61 164.32 MTB3 154.32 676.66 182.69 MTB4 33.75 145.17 39.19

[0057] 5. The detection results of soil bulk density, field moisture capacity and heavy metal content are shown in the following table.

[0058]

[0059]

[0060] As can be seen from the table, the physicochemical properties of the soil added with the soil repair agent are good, and the heavy metal leaching amount of most samples meets the national standard. In addition, the soil bulk density and field moisture capacity in the examples are slightly changed compared with normal soil, and the water retention capacity of the soil is improved.

[0061] According to the adjustment of the process parameters according to the content of the present application, the preparation of the composite material can be realized, and the performance tested shows basically the same performance as the present application. The above has made an exemplary description of the present application, and it should be explained that any simple transformation, modification or equivalent replacement which can not cost the creative labor of the person skilled in the art without departing from the core of the present application falls within the protection scope of the present application.

Claims

1. A tailings loaded biochar soil remediation agent, characterized in that, The tailings and food waste are mixed uniformly, ball-milling is performed, alkali liquor is added to the ball-milled mixture for water bath treatment, and after standing and drying, the mixture is subjected to temperature rising calcination and naturally cooled to room temperature, wherein: The mass ratio of the tailings to the food waste is (3-5):1, the tailings are molybdenum tailings, iron tailings or lead tailings, and the sum of the contents of chlorite and amphibole in the tailings is more than 20%, and the content of quartz is more than 70%; When ball-milling is performed, the mass ratio of the balls to the material is (2-3):1; The alkali liquor is an aqueous solution of sodium hydroxide or potassium hydroxide, the concentration is 3-5 mol / L, the temperature of the water bath treatment is 80-90 degrees Celsius, the time of the water bath treatment is 1-2 hours, and the standing is performed at room temperature of 20-30 degrees Celsius for 20-24 hours; In the temperature rising calcination process, a tube furnace or a microwave heater is used, and inert protective gas is introduced to ensure that the reaction is performed in an oxygen-free condition, the temperature of the temperature rising calcination is 450-750 degrees Celsius, and the time is 1-3 hours; Before use, the food waste is subjected to oil-water separation, 60 parts by mass of the food waste subjected to oil-water separation is taken, and 15-20 parts by mass of water and 15-20 parts by mass of hydroxide are mixed and stirred with the food waste and then standed, for standby, the stirring time is 1-2 hours, the stirring speed is 100-200 revolutions per minute, the standing time is 10-12 hours, and the standing temperature is 20-30 degrees Celsius.

2. The tailings-loaded biochar soil remediation agent according to claim 1, characterized in that, The mass ratio of the tailings to the food waste is 5:

1.

3. The tailings-loaded biochar soil remediation agent according to claim 1, characterized in that, The mass ratio of the balls to the material is 3:1, the ball-milling rotation speed is 500-800 rpm, and the grinding time is 30-60 minutes.

4. The tailings-loaded biochar soil remediation agent according to claim 1, characterized in that, The hydroxide is potassium hydroxide or sodium hydroxide.

5. The tailings-loaded biochar soil remediation agent according to claim 1, characterized in that, The temperature is raised from room temperature of 20-25 degrees Celsius at a rate of 5-10 degrees Celsius per minute, the temperature of the temperature rising calcination is 450-650 degrees Celsius, the time is 2-3 hours, and the inert protective gas is nitrogen, helium or argon.

6. A method of preparing a tailings loaded biochar soil amendment, characterized by, The tailings and food waste are mixed uniformly, ball-milling is performed, alkali liquor is added to the ball-milled mixture for water bath treatment, and after standing and drying, the mixture is subjected to temperature rising calcination and naturally cooled to room temperature, wherein: The mass ratio of the tailings to the food waste is (3-5):1, the tailings are molybdenum tailings, iron tailings or lead tailings, and the sum of the contents of chlorite and amphibole in the tailings is more than 20%, and the content of quartz is more than 70%; When ball-milling is performed, the mass ratio of the balls to the material is (2-3):1; The alkali liquor is an aqueous solution of sodium hydroxide or potassium hydroxide, the concentration is 3-5 mol / L, the temperature of the water bath treatment is 80-90 degrees Celsius, the time of the water bath treatment is 1-2 hours, and the standing is performed at room temperature of 20-30 degrees Celsius for 20-24 hours; In the temperature rising calcination process, a tube furnace or a microwave heater is used, and inert protective gas is introduced to ensure that the reaction is performed in an oxygen-free condition, the temperature of the temperature rising calcination is 450-750 degrees Celsius, and the time is 1-3 hours; Before use, the food waste is subjected to oil-water separation, and 60 parts by mass of the food waste subjected to oil-water separation is mixed with 15-20 parts by mass of water and 15-20 parts by mass of a hydroxide, stirred and left to stand, for use. The stirring time is 1-2 hours, the stirring speed is 100-200 revolutions per minute, the standing time is 10-12 hours, and the standing temperature is 20-30 degrees Celsius.

7. The method of claim 6, wherein the tailings-loaded biochar soil remediation agent is prepared by the steps of: a) mixing the tailings with the biochar; b) drying the mixture; and c) sieving the mixture to obtain the tailings-loaded biochar soil remediation agent. The mass ratio of the tailings to the food waste is 5:

1.

8. The method of claim 6, wherein the tailings-loaded biochar soil remediation agent is prepared by the steps of: a) mixing the tailings with the biochar; b) drying the mixture; and c) sieving the mixture to obtain the tailings-loaded biochar soil remediation agent. The mass ratio of the balls to the material is 3:1, the ball milling rotation speed is 500-800 rpm, and the grinding time is 30-60 minutes.

9. The method of claim 6, wherein the tailings-loaded biochar soil remediation agent is prepared by the steps of: a) mixing the tailings with the biochar; b) drying the mixture; and c) grinding the dried mixture to form the tailings-loaded biochar soil remediation agent. The hydroxide is potassium hydroxide or sodium hydroxide.

10. The method of claim 6, wherein the tailings loaded biochar soil amendment is prepared by, The temperature is raised from room temperature (20-25 degrees Celsius) at a rate of 5-10 degrees Celsius per minute, the temperature for heat preservation is 450-650 degrees Celsius, the time is 2-3 hours, and the inert protective gas is nitrogen, helium or argon.

Images