Method for large-scale treatment of polluted soil by using cement kiln and application

Abstract

The invention discloses a method for treating polluted soil on a large scale by utilizing a cement kiln and application. The method comprises the following steps: step 1, detecting the content of chloride ions and the aluminum-silicon ratio in the polluted soil; step 2, calcining the polluted soil by using a cement kiln to obtain an ecological sintered material; 2.1, when the chlorine ion content of the polluted soil is not higher than 1%, heavy metal reaches the standard, and the 28-day strength activity index is not lower than 65%, the polluted soil is calcined to obtain an ecological sintered material, and the ecological sintered material serves as an aluminum correction material to replace a mixed material for cement production; step 2.2, when the aluminum-silicon ratio is 0.3-0.4 and heavy metals reach the standard, doping solid wastes, and calcining to obtain a pozzolanic mixed material; and step 2.3, calcining the polluted soil which does not meet the control standards of the step 2.1 and the step 2.2 to obtain the ecological sintered material which can be used for preparing the baking-free brick. According to the method, resource utilization of the polluted soil is realized on the premise of polluted soil compatibility calcination management control.

Description

Technical Field

[0001] The present invention relates to the technical field of contaminated soil treatment and reuse, and in particular to a method and application of large-scale treatment of contaminated soil using a cement kiln. Background Art

[0002] Contaminated soil refers to soil in which the content of certain harmful substances exceeds the natural background value due to human activities (such as industrial production, mining, agricultural activities, etc.), causing adverse effects on the health of organisms, ecological balance or land use functions. These harmful substances can be heavy metals (such as lead, mercury, cadmium), organic pollutants (such as polycyclic aromatic hydrocarbons, pesticide residues, petroleum hydrocarbons), radioactive substances, etc.

[0003] Contaminated soil can reduce soil microbial activity, affect soil fertility, and further affect plant growth, disrupting the balance of the ecosystem. In addition, through the accumulation of the food chain, pollutants may enter the human body and cause various health problems, including but not limited to nervous system damage, cancer, reproductive system disorders, etc.

[0004] The existing methods for treating contaminated soil mainly include the following:

[0005] Excavation Removal: Contaminated soil is excavated and transported to a specific site for treatment or safe disposal.

[0006] Soil gas stripping: Applicable to the removal of volatile organic compounds, air is injected into the ground to cause the pollutants to evaporate, which are then collected and processed.

[0007] Solidification / stabilization technology: The addition of chemical reagents converts pollutants into a more stable, less toxic form, reducing their mobility and bioavailability.

[0008] Chemical redox: using chemical oxidants or reductants to react with pollutants to change the chemical properties of pollutants, making them less toxic or easier to handle.

[0009] Phytoremediation: Using plants and their roots to absorb, enrich or degrade pollutants in the soil, it is particularly suitable for treating lightly contaminated soils.

[0010] Microbial remediation: Degrading pollutants by enhancing the activity of microorganisms in the soil, suitable for the treatment of organic pollution.

[0011] Heat Treatment:

[0012] Thermal desorption: Separating pollutants from soil by heating, suitable for treating contaminated soil containing volatile or semi-volatile organic compounds.

[0013] The electric field is used to promote the migration of pollutants in the soil, thereby achieving centralized treatment.

[0014] However, existing repair methods are costly and have little added value. Summary of the invention

[0015] The purpose of the present invention is to provide a method for large-scale disposal of contaminated soil using cement kilns in order to address the problems of high cost and low added value of existing contaminated soil remediation methods.

[0016] Another object of the present invention is to provide an application of the method.

[0017] The technical solution adopted to achieve the purpose of the present invention is:

[0018] A method for large-scale disposal of contaminated soil using a cement kiln, characterized in that it comprises the following steps:

[0019] Step 1, detecting the chloride ion content and aluminum-silicon ratio in the contaminated soil;

[0020] Step 2, using a cement kiln to calcine the contaminated soil to obtain an ecological sintering material;

[0021] Step 2.1, when the chloride ion content of the contaminated soil is not higher than 1%, the heavy metal content is up to standard, and the 28-day strength activity index is not lower than 65%, the contaminated soil is calcined to obtain an ecological sintered material, and the ecological sintered material is used as an aluminum correction material to replace mixed materials for cement production;

[0022] Step 2.2, when the aluminum-silicon ratio is 0.3-0.4 and the heavy metal content meets the standard, solid waste is added and calcined to obtain a volcanic ash mixed material;

[0023] Step 2.3, the contaminated soil that does not meet the control standards of steps 2.1 and 2.2 is calcined to obtain an ecological sintered material that can be used to prepare unfired bricks.

[0024] In the above technical solution, the calcination temperature in step 2.1 is 860°C-880°C, and the kiln speed of the cement kiln is 3.3-3.6r / min.

[0025] In the above technical solution, the calcination temperature in step 2.2 is 700°C-750°C, and the kiln speed of the cement kiln is 2.0-2.6r / min.

[0026] In the above technical solution, the mass ratio of contaminated soil to solid waste in step 2.2 is 3:2-4:1.

[0027] In the above technical solution, the calcination temperature in step 2.3 is 860°C-880°C, and the kiln speed of the cement kiln is 3.3-3.6r / min.

[0028] The second aspect of the present invention provides a cement comprising 75.5-77.5 parts by mass of clinker, 4.5 parts by mass of desulfurized gypsum, 12-14 parts by mass of mineral powder, 0-3 parts by mass of limestone and 3-6 parts by mass of ecological sintering material prepared by the method described above.

[0029] In the above technical solution, the compression resistance of the cement is not less than 25MPa after 3 days and not less than 55MPa after 28 days.

[0030] The third aspect of the present invention provides a volcanic ash mixed material prepared by the method described.

[0031] The fourth aspect of the present invention provides a fire-free brick, comprising the above-mentioned ecological sintering material.

[0032] In the above technical solution, the unfired bricks include 40-50 parts by mass of ecological sintering materials, 15 parts by mass of cement, 10-20 parts by mass of slag and 20-30 parts by mass of waste bricks and stones.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention realizes the resource utilization of contaminated soil in cement production under the premise of management and control of calcination of contaminated soil.

[0035] 2. The present invention has developed a technology for preparing volcanic ash mixed materials by high-temperature sintering of contaminated soil supplemented with other active components, studied the influence of the raw material aluminum-silicon ratio, calcination temperature, calcination time, etc. on the product performance, and formed the optimal process conditions for the production of volcanic ash mixed materials, realizing the safe disposal of contaminated soil and high-value resource utilization.

[0036] 3. The present invention has developed a technology for preparing unburned bricks using ecological sintered materials based on the chemical composition, mineral composition and other characteristics of ecological sintered materials, optimized the types and proportions of various raw materials and preparation process parameters for unburned bricks, and realized the industrial production and engineering application of unburned bricks with a high dosage of 40-50% of ecological sintered materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The figure shows the effect of different calcination times on the strength activity index of the calcined samples in Example 2.

[0038] Figure 2 The figure shows the calcined material in Example 2, wherein a represents the fly ash slag doping amount of 10%, and b represents the fly ash slag doping amount of 50%.

[0039] Figure 3 Shown is the effect of different aluminum-silicon ratios on the strength activity index of the calcined samples in Example 2.

[0040] Figure 4 The figure shows the effect of different calcination temperature ratios on the strength activity index of the calcined samples in Example 2.

[0041] Figure 5 Shown is the XRD spectrum of the material before calcination in Example 2.

[0042] Figure 6 Shown is the XRD spectrum of the material after calcination in Example 2.

[0043] Figure 7 Shown is the X-ray fluorescence spectrum of the ecological sintering material in Example 3.

[0044] Figure 8 The figure shows the unfired brick sample after molding and demoulding in Example 3. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0046] Example 1

[0047] Low chloride ion content <1.0%, heavy metal contaminated soil that meets the standard, 28-day strength activity index reaches 65%, the contaminated soil is calcined at a calcination temperature of 860℃-880℃, and the kiln speed of the cement kiln is 3.3-3.6r / min to become ecological sintering material, which is reused in cement production. The raw material grinding part replaces bauxite, and the cement grinding part replaces limestone after ultra-fine grinding as a mixed material.

[0048] Ecological sintering materials are used as waste slag to participate in raw material batching, and the specific situation is that they are fed with aluminum correction materials in a ratio of 6:1. In daily production, neutron activation cement element analyzer is used for real-time monitoring, and the raw materials out of the mill are sampled and tested every two hours. The specific data are shown in 1-2.

[0049] Table 1 Statistics of chemical analysis of raw materials discharged from the mill every two hours

[0050]

[0051] Table 2 Statistical data of the clinker test every two hours Unit: %

[0052]

[0053] It can be seen from Table 1-2 that after adding 1 / 7 of the ecological sintering material into the raw material as aluminum correction material, the raw material composition is stable, the content of Al2O3, SiO2, CaO, and Fe2O3 in the raw material has no obvious fluctuation, the chemical components in the clinker are stable, the three rate values ​​are within the target control range, and the qualified rate of free calcium oxide is 100%. The addition of ecological sintering material has no effect on the quality of raw and clinker.

[0054] Ecological sintering materials are used to replace mixed materials in cement production: Ecological sintering materials are used to replace mixed materials in cement production tests, taking advantage of the fact that they remain active for 28 days, thereby reducing cement production costs.

[0055] Table 3 Chemical test results after adding ultrafine admixtures to cement

[0056]

[0057] Table 4 Physical properties test results after adding ultrafine admixtures to cement

[0058]

[0059] As shown in Table 3-4, after adding ultrafine admixtures to cement, the specific surface area increases accordingly, the consistency remains basically unchanged, the setting time is slightly extended, the fluidity of the net slurry decreases, and the time loss rate of the net slurry increases. When 3% ecological sintering material, 3% limestone, and 12% mineral powder are added, the strength of the cement in 3 days and 28 days is reduced. After the ecological sintering material completely replaces the limestone, the ecological sintering material is 6%, the mineral powder is 12%, and the strength in 3 days is reduced by 0.6MPa, and the strength in 28 days is reduced by 2.5MPa. When the mineral powder is increased to 14%, the amount of ecological sintering material remains unchanged at 6%, the strength in 3 days is reduced by 1.5MPa, and the strength in 28 days is basically the same as when 12% mineral powder is added.

[0060] Example 2

[0061] The aluminum-silicon ratio of contaminated soil is 0.3-0.4, and the heavy metal content meets the standard. It is mixed with fly ash slag and other ecological sintering materials obtained by calcining normal contaminated soil to produce materials with volcanic ash properties, which can replace secondary fly ash and can be used in mortar and concrete industries.

[0062] The contaminated soil used in this example is the contaminated soil produced by a factory site. The chemical analysis is shown in Table 5.

[0063] Table 5 Chemical analysis of contaminated soil Unit: %

[0064] serial number <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[R2O]]> <![CDATA[SO3]]> <![CDATA[Cl - ]]> Loss on ignition Mixed 40.71 6.95 9.98 12.02 2.25 1.85 1.43 0.183 10.60

[0065] From a mechanistic point of view, highly active SiO2 and Al2O3 are important factors affecting the volcanic ash qualification rate and strength activity index of calcined samples. Therefore, calcination can quickly remove the structural water of minerals in contaminated soil and convert it into amorphous, highly reactive SiO2 and Al2O3.

[0066] Calcination temperature is an important factor affecting the strength activity index of the sample. When calcined at 650-750℃, the crystal structure is transformed into a porous, disordered, amorphous structure, generating amorphous SiO2 and Al2O3. The strength activity index of the sample is the highest at 750℃.

[0067] Calcination time test: The calcination temperature was set at 750℃, and contaminated soil was used alone. The calcination time was set to 30min, 60min, 90min, and 120min. The effects of different calcination times on the volcanic ash properties and activity of the samples were studied. The results are as follows: Figure 1 shown.

[0068] pass Figure 1 Analysis shows that at a calcination temperature of 750°C, the 28-day strength activity index of the calcined sample first increases and then decreases with the increase of calcination time. When the calcination time is 30 minutes, the 28-day strength activity index reaches 67.53%. The activity improvement is not obvious with the increase of calcination time. Considering comprehensively, the calcination time is determined to be 30 minutes.

[0069] Pozzolanic mixed materials are mainly composed of silicon oxide and aluminum oxide. They are mineral materials that can react chemically with calcium hydroxide to form hydration products when added with water at room temperature. In order to further increase the ratio of silicon oxide to aluminum oxide in the contaminated soil, a certain proportion of fly ash slag is added for mixed calcination, thereby improving the volcanic ash qualification rate and strength activity index of the calcined samples.

[0070] The test plan is as follows:

[0071] The calcination temperature was set to 750 °C and the calcination time was set to 30 min. The calcination was carried out in a muffle furnace. The mass ratio of contaminated soil and fly ash slag was adjusted. The fly ash slag content was set to 10%, 20%, 30%, 40%, and 50%. The effects of different mixing ratios on the pozzolanic properties were studied. The results are shown in Table 6 and Figure 2 shown.

[0072] Table 6 Test data of volcanic ash properties at different ratios

[0073]

[0074] From Table 7 and Figure 3The test data show that when the calcination temperature is 750℃ and the aluminum-silicon ratio is greater than 0.32, the pozzolanic properties are all qualified. As the aluminum-silicon ratio increases, the 28-day strength activity index of the mixture increases first and then decreases. When the aluminum-silicon ratio is greater than 0.36 and the fly ash slag content is greater than 20%, the 28-day strength activity index of the mixture gradually decreases.

[0075] Table 7 Test data of different silicon-aluminum ratios

[0076]

[0077] The fly ash slag addition amount was set to 20%, the calcination time was set to 30min, and the calcination temperature was adjusted to 650℃, 750℃, 850℃, and 950℃. The effects of different calcination temperatures on the pozzolanic properties and 28-day strength activity index were studied. The results are shown in Table 8 and Figure 4 shown.

[0078] Table 8 Detection data of different calcination temperatures

[0079]

[0080] (Note: 1#, 2#, 3#, 4#; contaminated soil 80%, fly ash 20%)

[0081] The mixed materials before and after calcination were analyzed by X-ray fluorescence spectrometer. The XRD patterns are shown in Figure 5 , Figure 6 . Analysis of the XRD spectrum shows that the mixed material before calcination mainly contains mineral components such as quartz and calcium albite, and the mixed material after calcination is mainly quartz.

[0082] The chemical test analysis of the above four groups of experiments and the test data are shown in Table 9.

[0083] Table 9 Test data Unit: %

[0084] serial number Loss on ignition Sulfur trioxide <![CDATA[SiO2]]> <![CDATA[Al2O3]]> CaO <![CDATA[Al2O3 / SiO2]]> <![CDATA[(SiO2+Al2O3)]]> 1# 6.51 0.83 43.39 15.54 0.36 0.36 58.93 2# 5.92 0.88 43.31 15.48 0.36 0.36 58.79 3# 4.21 0.75 43.46 15.62 0.36 0.36 59.08 4# 3.85 0.72 43.40 15.57 0.36 0.36 58.97

[0085] According to the test results, when the calcination temperature is 750℃, all indicators meet the requirements of GB / T 2847-2022 "Pozzolanic mixed materials for cement". When the calcination temperature is greater than 750℃, the pozzolanic property is unqualified. In summary, when fly ash slag is added at 20% and the aluminum-silicon ratio is 0.36, a material with pozzolanic properties can be produced to replace secondary fly ash.

[0086] Example 3

[0087] The ecological sintered material after calcination can be used to prepare unburned bricks for the contaminated soil that does not meet the above control index requirements. The calcination temperature is 860℃-880℃, and the kiln speed of the cement kiln is 3.3-3.6r / min. The chemical composition of the ecological sintered material in this embodiment is shown in Table 10.

[0088] Table 10 Chemical composition analysis of ecological sintering materials Unit: %

[0089] project <![CDATA[SiO2]]> CaO <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> <![CDATA[Na2O]]> MgO <![CDATA[K2O]]> <![CDATA[Cl - ]]> LOSS 1# 45.76 10.78 11.75 5.20 2.37 2.22 2.09 0.69 15.98 2# 44.42 12.70 10.92 5.67 2.17 2.10 1.95 0.69 15.73 average 45.09 11.74 11.34 5.44 2.27 2.16 2.02 0.69 15.86

[0090] Through X-ray fluorescence spectrometer (XRF) analysis and chemical composition analysis, the results are as follows Figure 7 As shown, the main chemical components are SiO2, CaO and Al2O3, etc. The ecological sintering material contains mineral components such as quartz, calcite, dolomite and kyanite.

[0091] The particle grading analysis of the ecological sintered material is shown in Table 11. It can be found that the particles with a particle size of less than 0.6 mm account for 60%. The fine particles are conducive to full mixing with raw materials such as cement, easy to activate at an early stage, and can play a filling role in the preparation process of unfired bricks, which can appropriately increase the strength of unfired bricks.

[0092] Table 11 Particle gradation analysis of ecological sintering materials

[0093] Particle size distribution / mm Empty sieve / g Sieve + oversize / g Net weight / g Mass ratio / % >4.75 655.7 774.7 119.0 11.9 2.36～4.75 682.9 781.0 98.1 9.81 1.18～2.36 569.8 666.0 96.2 9.62 0.60～1.18 562.8 638.3 75.5 7.55 0.16～0.60 479.1 597.1 118.0 11.8 <0.16 460.8 954.0 493.2 49.32

[0094] The total amount of heavy metals and leaching content of ecological sintering materials were tested, and the results are shown in Tables 12 and 13. As can be seen from Table 12, the content of barium, zinc, manganese, copper and lead in ecological sintering materials is relatively high, the content of other heavy metals is low, and the overall heavy metal content is not high. As can be seen from Table 13, the leaching content of any heavy metal in ecological sintering materials is lower than the concentration value listed in GB5085.3-2007 "Identification of Hazardous Waste Identification Standard Leaching Toxicity Identification", indicating that ecological sintering materials do not have the leaching toxicity hazard characteristics, their environmental safety risks are controllable, and they can be used as resources.

[0095] In order to ensure the consistency of industrial experiments, the raw materials of Tianjin brick companies were used to carry out unfired brick experiments in the laboratory to determine the best production ratio plan and provide technical support for subsequent industrial experiments.

[0096] Table 12 Total amount of main heavy metals in ecological sintering materials Unit: mg / kg

[0097]

[0098] Table 13 Heavy metal leaching content of ecological sintering materials Unit: mg / L

[0099]

[0100]

[0101] Experiment on the preparation of unburned bricks using ecological sintering materials

[0102] Slag is industrial waste residue produced in the iron smelting process, with an f-CaO content of 0.04%. It is a slow-setting hydraulic cementitious material with low early strength and a certain late hardness. Its texture is relatively hard, and particles with a diameter of 2 to 7.5 mm account for 70%. Waste bricks and stones are construction waste generated in engineering projects, and the particle size after crushing is less than 5 mm.

[0103] In order to further determine the ratio and amount of each raw material in the preparation process of unburned bricks, the chemical composition of slag and waste bricks and stones was tested, and the results are shown in Tables 14 and 15.

[0104] Table 14 Chemical analysis of slag Unit: %

[0105] project <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO <![CDATA[K2O]]> MgO <![CDATA[Na2O]]> <![CDATA[Cl - ]]> 1# 59.73 17.65 9.38 7.37 1.78 1.55 1.10 0.08 2# 60.40 16.86 9.05 7.34 1.80 1.69 1.28 0.09 average 60.07 17.26 9.22 7.36 1.79 1.62 1.19 0.09

[0106] Table 15 Chemical analysis of waste masonry Unit: %

[0107]

[0108] According to a certain proportion, the ecological sintering material, cement, slag and waste bricks are placed in a mixer for dry mixing, and an appropriate amount of water is added to mix and stir for 10 minutes. Then the mixture is filled into a Φ50mm cylindrical mold for pressing and molding. After demoulding, it is placed in a standard curing box (temperature 20±1℃, relative humidity above 95%) for curing to the age to be tested, and the compressive strength test is carried out. After demoulding, the sample is as follows Figure 8 shown.

[0109] The mass ratio of ecological sintering materials, cement, slag and waste bricks was fixed at 45:15:15:25, and the molding pressure was set at 10MPa, 20MPa, 40MPa and 8MPa respectively. The relationship between the compressive strength of unburned bricks at 7d and 28d and the molding pressure was studied.

[0110] According to the results of laboratory research, it was preliminarily determined that the pressing pressure of unfired bricks is 20MPa, and the raw material ratio is: 40%-50% ecological sintering material, 15% cement, 10%-20% slag, and 20%-30% waste bricks and stones.

[0111] Based on the above laboratory research results, Jingbo Company adopted two raw material ratios according to the above experimental raw materials to carry out industrial experiments on the preparation of unfired bricks with ecological sintering materials. The ratio scheme is shown in Table 16.

[0112] Table 16: Industrial production formula for preparing unburned bricks using ecological sintered materials

[0113] Ratio Ecological sintering material / % cement / % Slag / % Waste bricks and stones / % Ratio 1 50 15 15 20 Ratio 2 40 15 15 30

[0114] First, the waste bricks and stones are placed in a crusher for crushing, and then the ecological sintering materials, cement, slag and crushed waste bricks and stones are mixed in a certain proportion, and the unburned bricks are produced using an automated brick-making machine. The test piece size is 190mm×90mm×50mm. After the unburned bricks are demoulded, they are cured in a curing room (pile shed) for 1 day, and then stacked and transferred to the outdoors for natural curing until 28 days.

[0115] The performance test and analysis of the unburned bricks after industrial production are shown in Table 17. As shown in Table 17, under the premise of 40% and 50% of the ecological sintering material, the compressive strength, water absorption rate, carbonization strength, softening coefficient, drying shrinkage rate, frost resistance, radioactivity and other performance indicators of the unburned bricks prepared by the two raw material ratios in the industrial test all meet the MU15 grade requirements in JC / T422-2007 "Non-sintered garbage tailings bricks", and there are no bumps, cracks, damage and stratification on the surface of the sample. Both formulas have been successful and qualified unburned bricks have been prepared. After testing by Tianjin No. 21 Station Testing Technology Co., Ltd., they all meet the MU15 grade requirements in JC / T422-2007 "Non-sintered garbage tailings bricks".

[0116] Table 17 Performance test results of unburned brick samples after industrial production

[0117]

[0118] The performance test of the above unburned brick samples meets the MU15 grade requirements (compressive strength ≥ 15MPa) in JC / T 422-2007 "Non-burned waste tailings bricks".

[0119] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for large-scale disposal of contaminated soil using cement kilns, characterized in that: The following steps are involved: Step 1, detecting the chloride ion content and aluminum-silicon ratio in the contaminated soil; Step 2, using a cement kiln to calcine the contaminated soil to obtain an ecological sintering material; Step 2.1, when the chloride ion content of the contaminated soil is not higher than 1%, the heavy metal content is up to standard, and the 28-day strength activity index is not lower than 65%, the contaminated soil is calcined to obtain an ecological sintered material, and the ecological sintered material is used as an aluminum correction material to replace mixed materials for cement production; Step 2.2, when the aluminum-silicon ratio is 0.3-0.4 and the heavy metal content meets the standard, solid waste is added and calcined to obtain a volcanic ash mixed material; Step 2.3, the contaminated soil that does not meet the control standards of step 2.1 and step 2.2 is calcined to obtain an ecological sintered material that can be used to prepare unfired bricks.

2. The method for large-scale disposal of contaminated soil using cement kilns as claimed in claim 1, characterized in that: In the step 2.1, the calcination temperature is 860° C.-880° C., and the kiln speed of the cement kiln is 3.3-3.6 r / min.

3. The method for large-scale disposal of contaminated soil using cement kilns as claimed in claim 1, characterized in that: In the step 2.2, the calcination temperature is 700° C.-750° C., and the kiln speed of the cement kiln is 2.0-2.6 r / min.

4. The method for large-scale disposal of contaminated soil using cement kilns as claimed in claim 1, characterized in that: In step 2.2, the mass ratio of contaminated soil to solid waste is 3:2-4:

1.

5. The method for large-scale disposal of contaminated soil using cement kilns as claimed in claim 1, characterized in that: In the step 2.3, the calcination temperature is 860° C.-880° C., and the kiln speed of the cement kiln is 3.3-3.6 r / min.

6. A cement, characterized in that: The invention comprises 75.5-77.5 parts by mass of clinker, 4.5 parts by mass of desulfurized gypsum, 12-14 parts by mass of mineral powder, 0-3 parts by mass of limestone and 3-6 parts by mass of ecological sintering material prepared by the method according to any one of claims 1-2.

7. The cement according to claim 5, characterized in that The cement has a 3-day compressive strength of not less than 25 MPa and a 28-day compressive strength of not less than 55 MPa.

8. A pozzolanic mixed material, characterized in that: It is prepared by the method according to any one of claim 1, claim 3 or claim 4.

9. A non-fired brick, characterized in that: Contains the ecological sintering material as described in claim 1 or claim 5.

10. The unfired brick according to claim 9, characterized in that: The unburned bricks include 40-50 parts by weight of ecological sintering materials, 15 parts by weight of cement, 10-20 parts by weight of slag and 20-30 parts by weight of waste bricks and stones.

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