Method for utilizing all components of polluted soil containing clay minerals
By drying, separating, alkali washing and pyrolysis the contaminated soil, a variety of intermediate products are separated and high-performance geopolymers are prepared, which solves the problems of process optimization and high cost in contaminated soil treatment, and realizes the efficient resource utilization of contaminated soil and the improvement of geopolymer performance.
Patent Information
- Application Number
- CN202510682674.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-26
- Publication Date
- 2025-09-26
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing technologies for contaminated soil treatment face difficulties in optimizing the calcination and geopolymer preparation processes. Geopolymer performance is unstable, production costs are high, and efficient resource utilization of contaminated soil is difficult to achieve.
By drying, separating, alkali washing, pyrolysis, and thermal activation of clay mineral-contaminated soil, sand and gravel, alkaline dust slurry, ecologically active soil, and tar are separated and converted into high-performance geopolymer slurry. The interaction between tar and geopolymer structure is utilized to enhance stability and performance.
The resource utilization of all components of contaminated soil is achieved, the treatment cost is reduced, the strength and toughness of geopolymers are improved, the added value is increased, and super-hydrophobic geopolymer slurry is prepared.
Smart Images
Figure CN120696202A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the intersecting field of solid waste resource utilization and material preparation, and specifically relates to a method for utilizing all components of contaminated soil containing clay minerals. Background Art
[0002] With the acceleration of industrialization and urbanization, soil pollution is becoming an increasingly prominent problem. Various industrial activities, excessive use of agricultural chemicals, and improper waste disposal have resulted in extensive soil contamination with pollutants such as heavy metals and organic matter. Contaminated soil not only severely damages the ecological environment but also poses a potential threat to human health. Currently, treatment methods for contaminated soil primarily include physical remediation, chemical remediation, and bioremediation. However, these traditional methods have limitations.
[0003] Geopolymers are three-dimensional inorganic polymers composed of silicon-oxygen tetrahedra and aluminum-oxygen tetrahedra. They possess advantages such as high strength, acid and alkali resistance, high temperature resistance, and rapid curing. In recent years, geopolymers have been widely used in building materials and solid waste management. The production of geopolymers by calcining contaminated soil not only renders it harmless but also transforms it into high-value-added building materials, achieving resource recycling. The calcination process decomposes organic matter in the contaminated soil and solidifies or converts heavy metals into stable forms, thereby reducing the mobility and harmfulness of pollutants.
[0004] Despite the enormous potential of calcining contaminated soil to produce geopolymers, this technology is still in its developmental stages. Practical applications still face several technical challenges, such as optimizing the combination of calcination and geopolymer preparation processes to improve their performance and stability, and reducing production costs to enhance the technology's economic viability. Therefore, developing an efficient, environmentally friendly, and economical technology for calcining contaminated soil to produce geopolymers is crucial for addressing soil pollution and achieving sustainable resource utilization. Summary of the Invention
[0005] The present invention provides a method for fully utilizing the components of clay mineral-contaminated soil. The method processes the clay mineral-contaminated soil to produce intermediate products, including sand and gravel, alkaline dust slurry, ecologically active soil, and tar, thereby recovering all the components of the clay mineral-contaminated soil. Furthermore, the intermediate products are prepared into geopolymers, thereby fully utilizing the components of the clay mineral-contaminated soil and increasing the added value of the clay mineral-contaminated soil.
[0006] In a first aspect, the present invention provides a method for utilizing all components of clay mineral-contaminated soil, characterized in that the method comprises the following steps:
[0007] Step 1: Leading clay mineral-contaminated soil to a dryer for drying to obtain dried soil and tail gas;
[0008] Step 2: The dried soil and tail gas in step 1 are respectively led to a separator for screening and an alkali washer for alkali washing, and contaminated clay and sand and gravel are obtained from the separator, and alkaline dust slurry is obtained from the alkali washer;
[0009] Step 3: The contaminated clay in step 2 is introduced into a pyrolyzer for pyrolysis and then introduced into a thermal activator for thermal activation to obtain pyrolysis gas and ecologically active soil;
[0010] Step 4: The pyrolysis gas is condensed to obtain tar and combustible gas, and the combustible gas is introduced into a thermal activator as a heat source to generate high-temperature tail gas in the thermally activated gas. The high-temperature tail gas is introduced into the pyrolyzer, and the tail gas after heat exchange is introduced into the dryer for drying.
[0011] Step 5: Collect sand and gravel, alkaline dust slurry, ecological active soil and tar products separately for use.
[0012] In any embodiment, the drying temperature in step 1 is 100°C to 105°C.
[0013] In any embodiment, the pyrolysis temperature in step 3 is 300° C. to 600° C.;
[0014] In any embodiment, the thermal activation temperature in step 3 is 650° C. to 900° C.;
[0015] In any embodiment, the thermal activation method in step three includes but is not limited to at least one of calcination activation and microwave activation.
[0016] In any embodiment, the temperature of the alkali solution for alkali washing in step 2 is controlled at 35°C to 85°C.
[0017] In any embodiment, the concentration of the alkali solution is controlled at 5% to 25%, and the alkali solution is one or more of KOH, NaOH, Na2CO3, and NaHCO3.
[0018] In any embodiment, the method for utilizing all components of clay mineral-contaminated soil further comprises the step of preparing a high-performance geopolymer slurry using sand and gravel, alkaline dust slurry, ecologically active soil and tar, specifically:
[0019] Step 1: The sand and alkaline dust slurry obtained in step 2 is introduced into an etching co-grinder for mechanical activation and alkaline excitation to obtain a porous, high specific surface area metastable slurry;
[0020] Step 2: The tar obtained in step 4, the ecological active soil obtained in step 3, and the metastable slurry obtained above are introduced into a modification reactor for modification to obtain a high-performance geopolymer slurry.
[0021] The metastable slurry is mixed with the ecological active soil and then excited by alkali to form a geopolymer. The geopolymer is composed of a polymerized Si-O-Al network structure, in which the silicon-oxygen tetrahedron (SiO4 4- ) and aluminum oxide tetrahedron (AlO4 5- ) are alternately bonded through shared oxygen atoms; at the same time, under the alkaline conditions provided by the alkaline dust slurry, the active components in the tar can interact with the generated geopolymer structure. On the one hand, the aromatic compounds in the tar can form weak non-covalent bond interactions with the silicon-oxygen and aluminum-oxygen structures in the geopolymer, such as π-π stacking, thereby enhancing the structural stability of the geopolymer; on the other hand, the reactive groups in the tar, such as hydroxyl (-OH) and carboxyl (-COOH), etc., undergo ion exchange reactions or form coordination bonds with the metal ions (such as alkali metal ions Na+, K+, etc.) in the geopolymer, thereby being embedded in the network structure of the geopolymer through Si-O-Si bonding to form a continuous organic film, combining the hydration products into an overall network, and enhancing the mechanical properties, water resistance and durability of the geopolymer.
[0022] In any embodiment, the mechanical activation is performed by mechanical grinding in an etching co-grinder, and the mechanical grinding time is 20 min to 100 min;
[0023] In any embodiment, the mass ratio of the sand and gravel to the alkaline dust slurry added in step 1 is 1:(2-5).
[0024] In any embodiment, the proportion of particles in the slurry at the outlet of the etching co-grinder with a particle size of less than 45 μm is 80% to 90%.
[0025] In any embodiment, the sand and gravel are screened at multiple stages, and sand and gravel of different particle sizes are compounded and then ground together in an etching co-grinder.
[0026] In any embodiment, the temperature of the modification reactor in step 2 is 50°C to 80°C.
[0027] In a second aspect, the present invention provides a high-performance geopolymer slurry, wherein the high-performance geopolymer slurry is superhydrophobic.
[0028] In any embodiment, the high performance geopolymer slurry is a geopolymer having a super hydrophobic composite coating of dense fiber bundles on the surface.
[0029] In a third aspect, the present invention provides a high-performance geopolymer slurry for application in the fields of building materials and solid waste treatment.
[0030] In a fourth aspect, the present invention provides a system for fully utilizing the components of clay mineral-contaminated soil, the system comprising:
[0031] Dryers, separators, pyrolyzers, thermal activators, alkali washers, condensers, etching co-mills, modification reactors and cyclone separators;
[0032] The dryer is connected to the separator, pyrolyzer, thermal activator, cyclone separator and modification reactor in sequence through pipelines;
[0033] The dryer is also connected to the alkali cleaner, the etching co-grinding device and the modification reactor in sequence through pipelines;
[0034] The pyrolyzer is further connected to a condenser and a modification reactor in sequence through a pipeline, or the pyrolyzer is further connected to a condenser, an etching co-grinder and a modification reactor in sequence through a pipeline, and the condenser is also connected to a thermal activator at the same time;
[0035] The separator is connected to the etching co-grinder through a pipeline, and the cyclone separator is also connected to the pyrolyzer and the dryer in sequence through pipelines.
[0036] During use, the clay mineral contaminated soil is dried in the dryer using tail gas, and then the tail gas enters the alkali washer and is absorbed by the alkali solution to obtain alkaline dust slurry, and then enters the etching co-grinder; the dried soil enters the separator and is separated to obtain contaminated clay and sand and gravel; the sand and gravel enter the etching co-grinder and are mixed and co-grinded with the alkaline dust slurry and then enter the modification reactor, and the contaminated clay enters the pyrolyzer and thermal activator in turn, and is pyrolyzed and thermally activated at high temperature to obtain ecologically active soil and high-temperature tail gas, which then enter the cyclone separator for gas-solid separation, and the obtained ecologically active soil enters the modification reactor, and the high-temperature tail gas enters the pyrolyzer and the heat exchange temperature is reduced, and the obtained tail gas enters the dryer to dry the clay mineral contaminated soil; the pyrolysis gas generated by the pyrolysis in the pyrolyzer enters the condenser from the pyrolyzer, and is condensed to obtain tar and combustible gas; the tar enters the etching co-grinder from the condenser and then enters the modification reactor or directly enters the modification reactor from the condenser, and the combustible gas enters the thermal activator from the condenser.
[0037] The present invention couples the contaminated soil resource utilization process with the geopolymer preparation technology, and has the following beneficial effects compared with the existing technology:
[0038] 1. This invention proposes a novel method for resource utilization of contaminated soil. By grading and separating the contaminated soil into sand and gravel and contaminated clay, the soil is then converted into high-value materials such as metastable slurry, ecologically active soil, and tar through processes such as pyrolysis, thermal activation, and etching and co-grinding. The entire process system features highly synergistic coupling of material and energy flows, reducing the cost of contaminated soil treatment, achieving resource utilization of all contaminated soil components, and significantly increasing the added value of the contaminated soil. The method has high application prospects.
[0039] 2. This invention innovates the raw materials and methods for preparing high-performance geopolymers. It utilizes the graded and quality-based conversion of contaminated soil into ecologically active soil and alkaline dust slurry. By controlling the mixing ratio, reaction temperature, alkalinity and other conditions, the tar is fully integrated into the three-dimensional network structure of the geopolymer, thereby achieving modification of the geopolymer. The resulting geopolymer has high strength and toughness, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0040] Figure 1 The figure is a schematic diagram of a process flow for utilizing all components of contaminated soil containing clay minerals according to the present invention.
[0041] Description of reference numerals:
[0042] 1—Dryer; 2—Separator; 3—Pyrolyzer; 4—Thermal activator; 5—Alkali washer; 6—Condenser; 7—Etching co-grinder; 8—Modification reactor; 9—Cyclone separator. DETAILED DESCRIPTION
[0043] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings.
[0044] In a first aspect, the present invention provides a method for utilizing all components of clay mineral-contaminated soil, characterized in that the method comprises the following steps:
[0045] Step 1: Lead the clay mineral-contaminated soil to a dryer for drying to obtain dried soil and tail gas;
[0046] Step 2: The dried soil and tail gas in step 1 are respectively led to a separator for screening and an alkali washer for alkali washing, and contaminated clay and sand and gravel are obtained from the separator, and alkaline dust slurry is obtained from the alkali washer;
[0047] Step 3: The contaminated clay in step 2 is introduced into a pyrolyzer for pyrolysis and then introduced into a thermal activator for thermal activation to obtain pyrolysis gas and ecologically active soil;
[0048] Step 4: The pyrolysis gas is condensed to obtain tar and combustible gas, and the combustible gas is introduced into a thermal activator as a heat source to generate high-temperature tail gas in the thermally activated gas. The high-temperature tail gas is introduced into the pyrolyzer, and the tail gas after heat exchange is introduced into the dryer for drying.
[0049] Step 5: Collect sand and gravel, alkaline dust slurry, ecological active soil and tar products separately for use.
[0050] In any embodiment, the drying temperature in step 1 is 100°C to 105°C.
[0051] In any embodiment, the pyrolysis temperature in step 3 is 300° C. to 600° C.;
[0052] When the pyrolysis temperature is lower than 300℃, the efficiency of organic matter decomposition and release is low. When the temperature is higher than 600℃, all organic matter may be decomposed and converted into small molecular combustible gas, and the tar yield is low.
[0053] In any embodiment, the thermal activation temperature in step 3 is 650° C. to 900° C.;
[0054] The clay minerals in the contaminated soil undergo crystal transformation when heated, forming ecologically active soil with volcanic ash activity.
[0055] In any embodiment, the thermal activation method in step 3 includes but is not limited to at least one of calcination activation and microwave activation;
[0056] The specific method of microwave activation is to add a microwave treatment step; the microwave conditions can be controlled to have a microwave power of 100W to 1000W and a microwave heating time of 5min to 50min.
[0057] In any embodiment, the temperature of the alkali solution for alkali washing in step 2 is controlled at 35° C. to 85° C.;
[0058] The tail gas of the present invention has a certain temperature. After the alkali solution is introduced, the alkali solution is heated to a certain temperature. The greater the amount of alkali solution added, the lower the temperature of the alkali solution, and the smaller the amount of alkali solution added, the higher the temperature of the alkali solution. Therefore, the temperature of the alkali solution can be better controlled by adjusting the amount of alkali solution.
[0059] If the temperature is controlled within this range, it will have a good etching effect on sand and gravel; if the temperature is lower than this range, the etching effect will be poor; if the temperature is higher than this range, alkali and other substances will be easily volatile, which will not only deteriorate the etching effect but also corrode the equipment.
[0060] In any embodiment, the concentration of the alkali solution is controlled at 5% to 25%, and the alkali solution is one or more of KOH, NaOH, Na2CO3, and NaHCO3;
[0061] Controlling the alkali solution concentration within this range will have a good etching effect on sand and gravel; if the concentration is lower than this range, the etching effect is poor, and if it is higher than this range, it will corrode the equipment.
[0062] In any embodiment, the method for utilizing all components of clay mineral-contaminated soil further comprises the step of preparing a high-performance geopolymer slurry using sand and gravel, alkaline dust slurry, ecologically active soil and tar, specifically:
[0063] Step 1, introducing the sand and alkaline dust slurry obtained above into an etching co-grinder, and mechanically grinding to obtain a porous, high-specific surface area metastable slurry; the sand and gravel are mixed with the alkaline dust slurry in the etching co-grinder and then mechanically ground. Under the action of mechanical force, the sand and gravel particles will produce lattice distortion and form lattice defects, resulting in an increase in their internal energy and enhanced reaction activity, which is conducive to etching and pore formation; in addition, the introduction of the alkaline dust slurry forms an alkali excitation effect on the sand and gravel, causing the silicon-oxygen bonds and aluminum-oxygen bonds of the sand and gravel to break, thereby forming a large number of oligomeric silicon (aluminum) tetrahedral unit structures, thereby obtaining a porous, high-specific surface area metastable slurry;
[0064] Step 2: The tar obtained above, the ecological active soil obtained in step 3, and the metastable slurry obtained above are all introduced into a modification reactor for modification to obtain a high-performance geopolymer slurry; the metastable slurry is an alkaline slurry with a certain volcanic ash activity and has a certain temperature. In the modification reactor, the metastable slurry is fully mixed with the tar and the ecological active soil. The ecological active soil produces a gelling substance through an alkali excitation reaction, which interacts with the tar to form a more stable and high-performance composite material, in which the tar plays the role of filling, bonding and enhancing anti-seepage, and provides strength and stability to the gelling material formed in the system.
[0065] In any embodiment, the mass ratio of the sand and gravel to the alkaline dust slurry added in step 1 is 1:(2-5).
[0066] In any embodiment, the added sand and gravel can also be subjected to multi-stage screening to achieve compounding of sand and gravel of different particle sizes, which is beneficial to reducing grinding costs and making the prepared geopolymer slurry more dense and stronger.
[0067] In any embodiment, the proportion of particles with a particle size of 45 μm or less in the slurry at the outlet of the etching co-grinder is 80% to 90%;
[0068] The particle size of the slurry particles is controlled below 45 μm, its specific surface area is increased, and the contact area with water is improved, thereby accelerating the hydration reaction rate and making the cementitious material produce higher strength in a shorter time.
[0069] In any embodiment, the temperature of the modification reactor in step 2 is 50°C to 80°C.
[0070] Controlling the temperature of the modified reactor to 50°C to 80°C can improve the reaction efficiency without causing a large amount of solvent evaporation.
[0071] In a second aspect, the present invention provides a high-performance geopolymer slurry, which is super-hydrophobic. The high-performance geopolymer slurry is a geopolymer having a super-hydrophobic composite coating of dense fiber bundles on its surface.
[0072] The superhydrophobicity gives the layer formed after the geopolymer slurry is coated good self-cleaning properties; the surface of the layer formed after coating has dense fiber bundles, which makes the resulting material have strong mechanical properties, such as good tensile and bending properties.
[0073] In a third aspect, the present invention provides a high-performance geopolymer slurry for application in the fields of building materials and solid waste treatment.
[0074] In a fourth aspect, the present invention provides a system for utilizing all components of clay mineral-contaminated soil. Figure 1 , the system comprising:
[0075] Dryer 1, separator 2, pyrolyzer 3, thermal activator 4, alkali cleaner 5, condenser 6, etching co-grinder 7, modification reactor 8 and cyclone separator 9;
[0076] The dryer 1 is connected to the separator 2, the pyrolyzer 3, the thermal activator 4, the cyclone separator 9 and the modification reactor 8 in sequence through a pipeline; the dryer 1 is also connected to the alkali cleaner 5, the etching co-grinder 7 and the modification reactor 8 in sequence through a pipeline; the pyrolyzer 3 is also connected to the condenser 6 and the modification reactor 8 in sequence through a pipeline, or the pyrolyzer 3 is also connected to the condenser 6, the etching co-grinder 7 and the modification reactor 8 in sequence through a pipeline, and the condenser 6 is also connected to the thermal activator 4 at the same time; the separator 2 is connected to the etching co-grinder 7 through a pipeline, and the cyclone separator 9 is also connected to the pyrolyzer 3 and the dryer 1 in sequence through a pipeline.
[0077] During use, the clay mineral-contaminated soil is dried in the dryer 1 using the tail gas, and then the tail gas enters the alkali scrubber 5 and is absorbed by the alkali solution to obtain alkaline dust slurry, and then enters the etching co-grinder 7; the dried soil enters the separator 2 to be separated to obtain contaminated clay and sand and gravel; the sand and gravel enter the etching co-grinder 7 to be blended and co-grinded with the alkaline dust slurry and then enter the modification reactor 8, and the contaminated clay enters the pyrolyzer 3 and the thermal activator 4 in turn to be pyrolyzed and thermally activated at high temperature to obtain ecologically active soil and high-temperature tail gas, which then enter the cyclone The separator 9 is subjected to gas-solid separation through a cyclone separator 9, and the obtained ecologically active soil enters the modification reactor 8. The high-temperature tail gas enters the pyrolyzer 3. After the heat exchange temperature is reduced, the tail gas obtained enters the dryer 1 to dry the clay mineral-contaminated soil; the pyrolysis gas generated by the pyrolysis in the pyrolyzer 3 enters the condenser 6 from the pyrolyzer, and tar and combustible gas are obtained through condensation; the tar enters the etching co-grinder 7 from the condenser 6 and then enters the modification reactor 8 or directly enters the modification reactor 8 from the condenser 6, and the combustible gas enters the thermal activator 4 from the condenser 6.
[0078] The clay mineral-contaminated soil used in the examples of the present invention and the comparative examples has an organic matter content of about 10 wt %, and a clay mineral component content, a sand and gravel content, and a water content of about 30 wt %.
[0079] Example 1
[0080] 1. Methods for utilizing all components of clay mineral-contaminated soil:
[0081] Step 1: Leading the clay mineral-contaminated soil to a dryer to dry the clay mineral-contaminated soil at 102° C. with the tail gas to obtain dried soil;
[0082] Step 2: The dried soil and tail gas in step 1 are respectively introduced into a separator for screening and an alkali washer for alkali washing at 60°C (alkali solution: KOH concentration 15wt%), and contaminated clay and sand are obtained from the separator, and alkaline dust slurry is obtained from the alkali washer;
[0083] Step 3: The contaminated clay in step 2 is sequentially introduced into a pyrolyzer and a thermal activator for pyrolysis at 500°C and calcination activation at 800°C to obtain pyrolysis gas and ecologically active soil;
[0084] Step 4: The pyrolysis gas is condensed to obtain tar and combustible gas, and the combustible gas is introduced into a thermal activator as a heat source to generate high-temperature tail gas in the thermally activated gas. The high-temperature tail gas is introduced into the pyrolyzer, and the tail gas after heat exchange is introduced into the dryer for drying.
[0085] Step 5: Collect sand and gravel, alkaline dust slurry, ecological active soil and tar products separately for use.
[0086] 2. Preparation of high performance geopolymer slurry:
[0087] Step 1: introducing the collected sand and alkaline dust slurry into an etching co-grinder at a mass ratio of 1:3, and mechanically activating the slurry until the particle size of the slurry at the outlet of the etching co-grinder is 85% or less of 45 μm, thereby obtaining a porous, high specific surface area metastable slurry;
[0088] Step 2: introducing the collected tar and ecological active soil and the metastable slurry obtained above into a modification reactor, adjusting the temperature of the modification reactor to react and modify at 65° C., and obtaining a high-performance geopolymer slurry.
[0089] Example 2
[0090] 1. Methods for utilizing all components of clay mineral-contaminated soil:
[0091] Step 1: introducing clay mineral-contaminated soil into a dryer and drying the clay mineral-contaminated soil at 100° C. with tail gas to obtain dried soil;
[0092] Step 2: The dried soil and tail gas in step 1 are respectively introduced into a separator for screening and an alkali washer for alkali washing at 35°C (alkali solution: NaOH concentration 25wt%), and contaminated clay and sand are obtained from the separator, and alkaline dust slurry is obtained from the alkali washer;
[0093] Step 3: The contaminated clay in step 2 is sequentially introduced into a pyrolyzer and a thermal activator for pyrolysis at 300°C and calcination activation at 900°C to obtain pyrolysis gas and ecologically active soil;
[0094] Step 4: The pyrolysis gas is condensed to obtain tar and combustible gas, and the combustible gas is introduced into a thermal activator as a heat source to generate high-temperature tail gas in the thermally activated gas. The high-temperature tail gas is introduced into the pyrolyzer, and the tail gas after heat exchange is introduced into the dryer for drying.
[0095] Step 5: Collect sand and gravel, alkaline dust slurry, ecological active soil and tar products separately for use.
[0096] 2. Preparation of high performance geopolymer slurry:
[0097] Step 1: introducing the sand and alkaline dust slurry into an etching co-grinder at a mass ratio of 1:4, and mechanically activating the slurry until the particle size of the slurry at the outlet of the etching co-grinder is less than 90%, thereby obtaining a porous, high specific surface area metastable slurry;
[0098] Step 2: introducing the above tar, the ecological active soil obtained in step 3, and the above metastable slurry into a modification reactor, adjusting the temperature of the modification reactor to react and modify at 50° C., and obtaining a high-performance geopolymer slurry.
[0099] Example 3
[0100] 1. Methods for utilizing all components of clay mineral-contaminated soil:
[0101] Step 1: introducing clay mineral contaminated soil into a dryer to dry the clay mineral contaminated soil at 105° C. through tail gas to obtain dried soil;
[0102] Step 2: The dried soil and tail gas in step 1 are respectively introduced into a separator for screening and an alkali washer for alkali washing at 85°C (alkali solution: Na2CO3 concentration 5wt%), and contaminated clay and sand are obtained from the separator, and alkaline dust slurry is obtained from the alkali washer;
[0103] Step 3: The contaminated clay in step 2 is sequentially introduced into a pyrolyzer and a thermal activator for pyrolysis at 600°C and calcination activation at 650°C to obtain pyrolysis gas and ecologically active soil;
[0104] Step 4: The pyrolysis gas is condensed to obtain tar and combustible gas, and the combustible gas is introduced into a thermal activator as a heat source to generate high-temperature tail gas in the thermally activated gas. The high-temperature tail gas is introduced into the pyrolyzer, and the tail gas after heat exchange is introduced into the dryer for drying.
[0105] Step 5: Collect sand and gravel, alkaline dust slurry, ecological active soil and tar products separately for use.
[0106] 2. Preparation of high performance geopolymer slurry:
[0107] Step 1: introducing the sand and alkaline dust slurry obtained above into an etching co-grinder at a mass ratio of 1:2, mechanically activating the slurry until the particle size of the slurry at the outlet of the etching co-grinder is less than 45 μm to 80%, and alkali-activated to obtain a porous, high-specific surface area metastable slurry;
[0108] Step 2: The obtained ecological active soil is introduced into a modification reactor, the above-obtained tar is introduced into an etching co-grinder and blended with the obtained metastable slurry, and then introduced into a modification reactor together with the ecological active soil. The temperature of the modification reactor is adjusted to react and modify at 80°C to obtain a high-performance geopolymer slurry.
[0109] Example 4
[0110] 1. Methods for utilizing all components of clay mineral-contaminated soil:
[0111] Step 1: introducing clay mineral contaminated soil into a dryer to dry the clay mineral contaminated soil at 105° C. through tail gas to obtain dried soil;
[0112] Step 2: The dried soil and tail gas in step 1 are respectively introduced into a separator for screening and an alkali washer for alkali washing at 35°C (alkali solution: NaHCO3 concentration 5wt%), and contaminated clay and sand are obtained from the separator, and alkaline dust slurry is obtained from the alkali washer;
[0113] Step 3: The contaminated clay in step 2 is sequentially introduced into a pyrolyzer and a thermal activator for pyrolysis at 300°C and calcination activation at 650°C to obtain pyrolysis gas and ecologically active soil;
[0114] Step 4: The pyrolysis gas is condensed to obtain tar and combustible gas, and the combustible gas is introduced into a thermal activator as a heat source to generate high-temperature tail gas in the thermally activated gas. The high-temperature tail gas is introduced into the pyrolyzer, and the tail gas after heat exchange is introduced into the dryer for drying.
[0115] Step 5: Collect sand and gravel, alkaline dust slurry, ecological active soil and tar products separately for use.
[0116] 2. Preparation of high performance geopolymer slurry:
[0117] Step 1: introducing the sand and alkaline dust slurry obtained above into an etching co-grinder at a mass ratio of 1:5, mechanically activating the slurry until the particle size of the slurry at the outlet of the etching co-grinder is less than 90% of that of 45 μm, and alkali-activated to obtain a porous, high-specific surface area metastable slurry;
[0118] Step 2: introducing the obtained tar, ecological active soil and the metastable slurry obtained above into a modification reactor, adjusting the temperature of the modification reactor to react and modify at 50° C., and obtaining a high-performance geopolymer slurry.
[0119] Comparative Example 1
[0120] 1. Methods for utilizing all components of clay mineral-contaminated soil:
[0121] Step 1: Leading the clay mineral-contaminated soil to a dryer to dry the clay mineral-contaminated soil at 102° C. with the tail gas to obtain dried soil;
[0122] Step 2: The dried soil and tail gas in step 1 are respectively introduced into a separator for screening and an alkali washer for alkali washing at 60°C (alkali solution: KOH concentration 15wt%), and contaminated clay and sand are obtained from the separator, and alkaline dust slurry is obtained from the alkali washer;
[0123] Step 3: The contaminated clay in step 2 is introduced into a pyrolyzer and a thermal activator in sequence, pyrolyzed at 650°C and calcined and activated at 800°C to obtain pyrolysis gas and ecologically active soil;
[0124] Step 4: The pyrolysis gas is condensed to obtain tar and combustible gas, and the combustible gas is introduced into a thermal activator as a heat source to generate high-temperature tail gas in the thermally activated gas. The high-temperature tail gas is introduced into the pyrolyzer, and the tail gas after heat exchange is introduced into the dryer for drying.
[0125] Step 5: Collect sand and gravel, alkaline dust slurry, ecological active soil and tar products separately for use.
[0126] 2. Preparation of high performance geopolymer slurry:
[0127] Same as Example 1.
[0128] Comparative Example 2
[0129] 1. Methods for utilizing all components of clay mineral-contaminated soil:
[0130] Step 1: Leading the clay mineral-contaminated soil to a dryer to dry the clay mineral-contaminated soil at 102° C. with the tail gas to obtain dried soil;
[0131] Step 2: The dried soil and tail gas in step 1 are respectively introduced into a separator for screening and an alkali washer for alkali washing at 60°C (alkali solution: KOH concentration 15wt%), and contaminated clay and sand are obtained from the separator, and alkaline dust slurry is obtained from the alkali washer;
[0132] Step 3: The contaminated clay in step 2 is sequentially introduced into a pyrolyzer and a thermal activator, pyrolyzed at 500°C and calcined and activated at 600°C to obtain pyrolysis gas and ecologically active soil;
[0133] Step 4: The pyrolysis gas is condensed to obtain tar and combustible gas, and the combustible gas is introduced into a thermal activator as a heat source to generate high-temperature tail gas in the thermally activated gas. The high-temperature tail gas is introduced into the pyrolyzer, and the tail gas after heat exchange is introduced into the dryer for drying.
[0134] Step 5: Collect sand and gravel, alkaline dust slurry, ecological active soil and tar products separately for use.
[0135] 2. Preparation of high performance geopolymer slurry:
[0136] Same as Example 1.
[0137] Comparative Example 3
[0138] 1. Methods for utilizing all components of clay mineral-contaminated soil:
[0139] Same as Example 1.
[0140] 2. Preparation of high performance geopolymer slurry:
[0141] Step 1: introducing the sand and gravel obtained in step 2 and the alkaline dust slurry into an etching co-grinder at a mass ratio of 1:3, mechanically activating the slurry until the particle size of the slurry at the outlet of the etching co-grinder is less than 45 μm to 70%, and alkali-activated to obtain a porous, high-specific surface area metastable slurry;
[0142] Step 2: introducing the collected tar and ecological active soil and the metastable slurry obtained above into a modification reactor, adjusting the temperature of the modification reactor to react and modify at 65° C., and obtaining a high-performance geopolymer slurry.
[0143] Comparative Example 4
[0144] 1. Methods for utilizing all components of clay mineral-contaminated soil:
[0145] Same as Example 1.
[0146] 2. Preparation of high performance geopolymer slurry:
[0147] Step 1: directly mix the sand and gravel obtained above with the alkaline dust slurry in a mass ratio of 1:3 (without mechanical grinding) to obtain a mixed slurry;
[0148] Step 2: introducing the collected tar and ecological active soil and the mixed slurry into a modification reactor, adjusting the temperature of the modification reactor to react and modify at 65° C., and obtaining a high-performance geopolymer slurry.
[0149] Comparative Example 5
[0150] 1. Methods for utilizing all components of clay mineral-contaminated soil:
[0151] Step 1: Leading the clay mineral-contaminated soil to a dryer to dry the clay mineral-contaminated soil at 102° C. with the tail gas to obtain dried soil;
[0152] Step 2: The dried soil and tail gas in step 1 are respectively led to a separator for screening and an alkali washer for water washing at 60°C, and contaminated clay and sand are obtained from the separator, and dust slurry is obtained from the alkali washer;
[0153] Step 3: The contaminated clay in step 2 is sequentially introduced into a pyrolyzer and a thermal activator for pyrolysis at 500°C and calcination activation at 800°C to obtain pyrolysis gas and ecologically active soil;
[0154] Step 4: The pyrolysis gas is condensed to obtain tar and combustible gas, and the combustible gas is introduced into a thermal activator as a heat source to generate high-temperature tail gas in the thermally activated gas. The high-temperature tail gas is introduced into the pyrolyzer, and the tail gas after heat exchange is introduced into the dryer for drying.
[0155] Step 5: Collect sand, gravel, dust slurry, ecological active soil and tar products separately for use.
[0156] 2. Preparation of high performance geopolymer slurry:
[0157] Step 1: introducing the sand and dust slurry obtained above into an etching co-grinder for grinding at a mass ratio of 1:3, wherein the proportion of particles with a particle size of less than 45 μm at the outlet of the etching co-grinder is 85% to obtain a mixed slurry;
[0158] Step 2: introducing the above-obtained tar, ecological active soil and mixed slurry into a modification reactor, adjusting the temperature of the modification reactor to react and modify at 65° C., and obtaining geopolymer slurry.
[0159] Performance Testing
[0160] The test method refers to DB37 / T 5191-2021 Technical Specification for Reinforcement of High Ductility Concrete.
[0161] Table 1 Main mechanical properties of high ductility concrete (standard curing age 28 days)
[0162]
[0163] It can be seen that the method of treating clay mineral-contaminated soil of the present invention can realize the utilization of all components, and the geopolymer prepared using the method has good mechanical properties and superhydrophobic properties, which can greatly improve the added value of clay mineral-contaminated soil. The method of the present invention is simple and does not produce waste liquid during the process, and has good application prospects.
Claims
1. A method for utilizing all components of clay mineral-contaminated soil, characterized in that: The method comprises the following steps: Step 1: Leading clay mineral-contaminated soil to a dryer for drying to obtain dried soil and tail gas; Step 2: The dried soil and tail gas in step 1 are respectively led to a separator for screening and an alkali washer for alkali washing, and contaminated clay and sand and gravel are obtained from the separator, and alkaline dust slurry is obtained from the alkali washer; Step 3: The contaminated clay in step 2 is introduced into a pyrolyzer for pyrolysis and then introduced into a thermal activator for thermal activation to obtain pyrolysis gas and ecologically active soil; Step 4: The pyrolysis gas is condensed to obtain tar and combustible gas, and the combustible gas is introduced into a thermal activator as a heat source to generate high-temperature tail gas, which is introduced into a pyrolyzer and then passed into a dryer for drying. Step 5: Collect sand and gravel, alkaline dust slurry, ecological active soil and tar products separately for use.
2. The method for utilizing all components of clay mineral-contaminated soil according to claim 1, characterized in that: The pyrolysis temperature in step 3 is 300°C to 600°C, and the thermal activation temperature in step 3 is 650°C to 900°C.
3. The method for utilizing all components of clay mineral-contaminated soil according to claim 1, characterized in that: The thermal activation method in step three includes but is not limited to at least one of calcination activation and microwave activation.
4. The method for utilizing all components of clay mineral-contaminated soil according to claim 1, characterized in that: The temperature of the alkali solution for alkali washing in step 2 is controlled at 35°C to 85°C.
5. The method for utilizing all components of clay mineral-contaminated soil according to claim 1, characterized in that: The method also includes the steps of collecting sand and gravel, alkaline dust slurry, ecological active soil and tar to prepare high-performance geopolymer slurry, specifically: Step 1: The collected sand and alkaline dust slurry is introduced into an etching co-grinder for mechanical activation and alkali excitation to obtain a porous, high specific surface area metastable slurry; Step 2: The collected tar, ecological active soil and metastable slurry are introduced into a modification reactor for modification to obtain high-performance geopolymer slurry.
6. The method for utilizing all components of clay mineral-contaminated soil according to claim 5, characterized in that: The mass ratio of the sand and gravel to the alkaline dust slurry added in step 1 is 1:(2-5).
7. The method for utilizing all components of clay mineral-contaminated soil according to claim 5, characterized in that: The temperature of the modification reactor in step 2 is 50°C to 80°C.
8. A high performance geopolymer slurry, characterized in that: Prepared by the method according to any one of claims 5 to 7, the high-performance geopolymer slurry is superhydrophobic.
9. The high performance geopolymer slurry according to claim 8, characterized in that Applied in the fields of building materials and solid waste treatment.
10. A system for utilizing all components of clay mineral-contaminated soil, characterized in that: The system comprises: A dryer, a separator, a pyrolyzer, a thermal activator, an alkali washer, a condenser, an etching co-grinder, a modification reactor and a cyclone separator; the dryer is connected to the separator, the pyrolyzer, the thermal activator, the cyclone separator and the modification reactor in sequence through a pipeline; the dryer is also connected to the alkali washer, the etching co-grinder and the modification reactor in sequence through a pipeline; the pyrolyzer is also connected to the condenser and the modification reactor in sequence through a pipeline or the pyrolyzer is also connected to the condenser, the etching co-grinder and the modification reactor in sequence through a pipeline, and the condenser is also connected to the thermal activator at the same time; the separator is connected to the etching co-grinder through a pipeline, and the cyclone separator is also connected to the pyrolyzer and the dryer in sequence through a pipeline.