A method for preparing hydrothermal bricks using landfill humus and the hydrothermal bricks themselves.
By acid leaching and alkali dissolution treatment of landfill humus, water glass is prepared and mixed with slag and lime to form a cross-linked structure, which solves the problems of poor mechanical strength and heavy metal leaching of humus hydrothermal bricks, and realizes the preparation of high-strength and low-cost hydrothermal bricks.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENZHEN ENERGY ENVIRONMENT ENG CO LTD
- Filing Date
- 2024-02-18
- Publication Date
- 2026-05-26
AI Technical Summary
In existing technologies, the hydrothermal bricks prepared from landfill humus soil have poor mechanical strength due to their high organic content, and the presence of heavy metal ions can easily leach out after long-term use, causing secondary pollution.
By calcining humus mixed with sodium salt, crushing and grinding it, and then acid leaching it, a dry gel is obtained. Then, NaOH solution is added to prepare water glass. After mixing with slag, lime and water, it is molded and subjected to hydrothermal reaction to form silica sol and cross-link with organic matter, thus fixing heavy metal ions.
The prepared hydrothermal bricks have high mechanical strength and compressive strength, are not prone to leaching of heavy metals during long-term use, are highly safe, have low cost, and are suitable for industrial processing.
Smart Images
Figure CN118063181B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of landfill humus resource utilization, specifically to a method for preparing hydrothermal bricks using landfill humus and the hydrothermal bricks themselves. Background Technology
[0002] Stale landfill waste refers to municipal solid waste that has been stored in landfills or piled up for many years. Stale landfill waste contains impurities such as wood, plastic, textiles, glass, metal, and test blocks, as well as humus. Impurities account for approximately 40-50%, and humus accounts for approximately 50-60%. Because municipal solid waste also contains waste batteries and electronic products, which contain significant amounts of heavy metals, these heavy metals can seep into the humus in landfills over long periods, causing heavy metal contamination. To treat this heavy metal-contaminated landfill humus, it is often used as backfill material and cover soil for other landfills. However, because landfill humus contains high levels of heavy metals, and its salt content and organic matter levels also exceed standards, it fails to meet the "Greening Planting Soil" (CJ / T3402016) standard. Without improvement, humus cannot be used for landscaping, resulting in a significant waste of soil resources.
[0003] To achieve the resource utilization of landfill humus, two common methods are employed: First, the humus is remediated. This can be done by adding soil conditioners to remove or fix heavy metal ions in the landfill humus. For example, Chinese patent CN104560047B (righted) discloses adding heavy metal passivating agents to the soil, including humic acid and thiol compounds. However, this method only effectively reduces plant absorption of mercury and does not solve the problem completely. Furthermore, this method requires the addition of large amounts of treatment reagents, resulting in high processing costs and low added value for the landfill humus. Second, the humus is developed into new products. For instance, Chinese patent CN114702296A (withdrawn) attempted to mix landfill humus with additives and construction waste, followed by aging, drying, and sintering to produce bricks. This method not only achieves resource utilization of humus but also increases its added economic value. However, this method did not treat landfill humus. Since landfill humus contains a large amount of organic matter, this organic matter hinders hydration and affects the development of the gel structure when used to make bricks, ultimately resulting in bricks with poor mechanical strength. Furthermore, the large amount of heavy metal ions in landfill humus can be initially fixed during brick making through processes such as high-temperature firing, preventing leaching during short-term use. However, with long-term use, these heavy metal ions will leach out, causing secondary pollution.
[0004] Hydrothermal bricks can be used as paving bricks and road slabs, and have low requirements for raw materials. Preparing hydrothermal bricks from landfill humus does not require fine impurity removal from the landfill humus, making it a good way to realize the resource utilization of landfill humus. Sodium silicate is expensive; if it is used directly as an alkali activator, the production cost of hydrothermal bricks will be high. How to prepare high-performance hydrothermal bricks using landfill humus at a low cost remains a worthy research problem in this field. At the same time, a reasonable and effective method for preparing high-performance hydrothermal bricks using landfill humus is needed. Summary of the Invention
[0005] To address the problems of poor mechanical strength in hydrothermal bricks made directly from landfill humus due to its high organic matter content, and secondary pollution caused by the leaching of heavy metal ions from landfill humus after long-term use, this invention provides a method for preparing hydrothermal bricks using landfill humus, and the resulting hydrothermal bricks.
[0006] To achieve the above objectives, the specific technical solution adopted by the present invention is as follows:
[0007] A method for preparing hydrothermal bricks using landfill humus includes the following steps:
[0008] Step 1: After mixing humus with sodium salt, calcin the mixture, crush and grind it, add acid solution for acid leaching, separate the solid and liquid, and dry the resulting solid material to obtain a dry gel.
[0009] Step 2: Add NaOH solution to the obtained dry gel to dissolve it, and prepare water glass;
[0010] Step 3: Take another batch of humus, slag, lime and water, mix them evenly, then add the water glass obtained in step 2 and mix evenly to obtain a slurry;
[0011] Step 4: Mold the obtained slurry to obtain standard bricks, and then subject the standard bricks to a hydrothermal reaction to obtain hydrothermal bricks.
[0012] In some embodiments, the sodium salt in step 1 is selected from at least one of sodium carbonate, sodium sulfate, sodium nitrate and sodium chloride, and the amount of sodium salt added in step 1 is 15%-50% of the total mass of humus and sodium salt.
[0013] In some embodiments, the calcination temperature in step 1 is 800-1100℃, and the calcination time is 2-4h.
[0014] In some embodiments, the acid solution in step 1 is one of sulfuric acid solution, nitric acid solution, acetic acid solution and hydrochloric acid solution;
[0015] In some embodiments, the concentration of the acid solution is 5-10 mol / L, and the amount of acid added is based on a solid-liquid ratio of 1:5-1:10.
[0016] In some embodiments, the drying temperature in step 1 is 50-100°C, and the drying time is 2-5 hours.
[0017] In some embodiments, the concentration of the sodium hydroxide solution in step 2 is 1%-10%, and the amount of sodium hydroxide solution added is 3-5 times the mass of the dry gel.
[0018] In some embodiments, the humus, slag, lime, water, and water glass in step 3 account for 50-75 wt%, 10-30 wt%, 5-10 wt%, 5-15 wt%, and 4-10 wt% of the slurry, respectively.
[0019] In some embodiments, the compression molding pressure in step 4 is 10-20 MPa.
[0020] In some embodiments, the hydrothermal reaction in step 4 is carried out under high temperature and high pressure, with a temperature of 180-210°C and a pressure of 1.2-1.3 MPa, and the hydrothermal reaction time is at least 10 hours.
[0021] The present invention also proposes a hydrothermal brick, which is prepared by the method described above.
[0022] This invention first uses humus to prepare water glass containing impurities, and then adds the prepared water glass to the raw materials for preparing hydrothermal bricks. Since the mixture obtained by mixing humus, slag, lime and water is alkaline, after adding water glass, the water glass forms silica sol in this alkaline environment, and the silica sol contains active silanol groups.
[0023] Humus contains a large amount of organic matter, which contains a lot of hydroxyl and carboxyl groups. The silanol groups in silica sol react with the hydroxyl and carboxyl groups in the organic matter to cross-link and promote the formation of a gel network structure, which can enhance the gel skeleton structure and improve the mechanical properties of the prepared hydrothermal bricks.
[0024] In addition, the heavy metals in the humus are initially fixed by the organic matter in the humus, and the added water glass can act as an infinite binder to encapsulate and fix the heavy metals, thereby reducing the leaching rate of heavy metals.
[0025] Furthermore, the gel network structure formed by the cross-linking reaction of water glass with carboxyl and hydroxyl groups in organic matter further enhances the fixation effect on heavy metals, ultimately locking the heavy metals firmly in the structure of the prepared hydrothermal brick, thus inhibiting and reducing the leaching of heavy metals after long-term use.
[0026] The beneficial effects of this invention are as follows:
[0027] 1. The method of the present invention adds water glass to the preparation of hydrothermal bricks to form crosslinks with organic matter, and the prepared hydrothermal bricks have good mechanical strength, with a compressive strength of up to 16 MPa, and have good application prospects;
[0028] 2. The heavy metals in the hydrothermal bricks prepared by the method of the present invention are well fixed, and the heavy metals are not easy to leach out during long-term use, which does not easily cause secondary pollution and has high safety.
[0029] 3. The preparation method provided by this invention is simple and easy to operate, requires fewer raw materials, and has a lower preparation cost. It is suitable for industrial-scale processing of landfill humus, which not only realizes the resource utilization of humus, but also greatly improves the added value of humus. Attached Figure Description
[0030] Figure 1 This is a flowchart illustrating the method for preparing hydrothermal bricks from landfill humus in an embodiment of the present invention. Detailed Implementation
[0031] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.
[0032] like Figure 1 The diagram shown is a flowchart of a method for preparing hydrothermal bricks using landfill humus in an embodiment of the present invention. As can be seen, this embodiment of the present invention proposes a method for preparing hydrothermal bricks using landfill humus, comprising the following steps:
[0033] Step 1: After mixing humus with sodium salt, calcin the mixture, crush and grind it, add acid solution for acid leaching, separate the solid and liquid, and dry the resulting solid material to obtain a dry gel.
[0034] Step 2: Add NaOH solution to the dry gel to dissolve it, and water glass is obtained;
[0035] Step 3: Take another batch of humus, slag, lime and water, mix them evenly, then add the water glass and mix evenly to obtain a slurry;
[0036] Step 4: Mold the slurry to obtain standard bricks, and then subject the standard bricks to a hydrothermal reaction to obtain hydrothermal bricks.
[0037] This invention provides a method for preparing hydrothermal bricks using landfill humus and the resulting hydrothermal bricks. The preparation method is simple, and the prepared hydrothermal bricks have high mechanical strength and are less prone to heavy metal leaching after long-term use, showing good application prospects and effectively realizing the resource utilization of landfill humus. Specific embodiments and comparative examples are shown below:
[0038] Example 1
[0039] Step 1: Mix 65 parts of humus soil with 35 parts of sodium carbonate and calcine at 950℃ for 3 hours. After crushing and grinding, add 700 parts of 8mol / L sulfuric acid solution for acid leaching. After solid-liquid separation, dry the obtained solid material at 80℃ for 4 hours to obtain dry gel.
[0040] Step 2: Add 6wt% NaOH solution (4 times the mass of the dry gel) to the obtained dry gel for alkaline dissolution to obtain water glass;
[0041] Step 3: Take another 60 parts of humus, 20 parts of slag, 8 parts of lime and 10 parts of water and mix them evenly. Then add the 7 parts of water glass obtained in step 2 and mix evenly to obtain a slurry.
[0042] Step 4: The obtained slurry is molded at 15 MPa to obtain standard bricks. Then, the standard bricks are subjected to hydrothermal reaction at 195℃ and 1.2 MPa to obtain hydrothermal bricks.
[0043] Example 2
[0044] Step 1: Mix 65 parts of humus soil with 35 parts of sodium carbonate and calcine at 950℃ for 3 hours. After crushing and grinding, add 500 parts of 10mol / L sulfuric acid solution for acid leaching. After solid-liquid separation, dry the obtained solid material at 80℃ for 4 hours to obtain dry gel.
[0045] Step 2: Add 6wt% NaOH solution (4 times the mass of the dry gel) to the obtained dry gel for alkaline dissolution to obtain water glass;
[0046] Step 3: Take another 60 parts of humus, 20 parts of slag, 8 parts of lime and 10 parts of water and mix them evenly. Then add the 4 parts of water glass obtained in step 2 and mix evenly to obtain a slurry.
[0047] Step 4: The obtained slurry is molded at 15 MPa to obtain standard bricks. Then, the standard bricks are subjected to hydrothermal reaction at 210℃ and 1.3 MPa to obtain hydrothermal bricks.
[0048] Example 3
[0049] Step 1: Mix 50 parts of humus soil with 50 parts of sodium carbonate and calcine at 800℃ for 4 hours. After crushing and grinding, add 700 parts of 8mol / L sulfuric acid solution for acid leaching. After solid-liquid separation, dry the obtained solid material at 80℃ for 4 hours to obtain dry gel.
[0050] Step 2: Add 1 wt% NaOH solution (5 times the mass of the dry gel) to the obtained dry gel for alkaline dissolution to obtain water glass;
[0051] Step 3: Take another 50 parts of humus, 30 parts of slag, 5 parts of lime and 15 parts of water and mix them evenly. Then add the 10 parts of water glass obtained in Step 2 and mix evenly to obtain a slurry.
[0052] Step 4: The obtained slurry is molded at 15 MPa to obtain standard bricks. Then, the standard bricks are subjected to hydrothermal reaction at 180℃ and 1.2 MPa to obtain hydrothermal bricks.
[0053] Example 4
[0054] Step 1: Mix 85 parts of humus soil with 15 parts of sodium nitrate and calcine at 1100℃ for 2 hours. After crushing and grinding, add 1000 parts of 5mol / L nitric acid solution for acid leaching. After solid-liquid separation, dry the obtained solid material at 80℃ for 4 hours to obtain dry gel.
[0055] Step 2: Add 10wt% NaOH solution (3 times the mass of the dry gel) to the obtained dry gel for alkaline dissolution to obtain water glass;
[0056] Step 3: Take another 75 parts of humus, 10 parts of slag, 10 parts of lime and 15 parts of water and mix them evenly. Then add the 10 parts of water glass obtained in step 2 and mix evenly to obtain a slurry.
[0057] Step 4: The obtained slurry is molded at 20 MPa to obtain standard bricks. Then, the standard bricks are subjected to hydrothermal reaction at 180℃ and 1.2 MPa to obtain hydrothermal bricks.
[0058] Example 5
[0059] Step 1: Mix 65 parts of humus soil with 35 parts of sodium sulfate and calcine at 950℃ for 3 hours. After crushing and grinding, add 700 parts of 8mol / L sulfuric acid solution for acid leaching. After solid-liquid separation, dry the obtained solid material at 80℃ for 4 hours to obtain dry gel.
[0060] Step 2: Add 6wt% NaOH solution (4 times the mass of the dry gel) to the obtained dry gel for alkaline dissolution to obtain water glass;
[0061] Step 3: Take another 60 parts of humus, 20 parts of slag, 8 parts of lime and 5 parts of water and mix them evenly. Then add the 4 parts of water glass obtained in step 2 and mix evenly to obtain a slurry.
[0062] Step 4: The obtained slurry is molded at 10 MPa to obtain standard bricks. Then, the standard bricks are subjected to hydrothermal reaction at 195℃ and 1.2 MPa to obtain hydrothermal bricks.
[0063] Comparative Example 1
[0064] Step 1: Mix 65 parts of humus soil with 35 parts of sodium carbonate and calcine at 950℃ for 3 hours. After crushing and grinding, add 700 parts of 8mol / L sulfuric acid solution for acid leaching. After solid-liquid separation, dry the obtained solid material at 80℃ for 4 hours to obtain dry gel.
[0065] Step 2: Add 6wt% NaOH solution (4 times the mass of the dry gel) to the obtained dry gel for alkaline dissolution to obtain water glass;
[0066] Step 3: Take another 60 parts of humus, 8 parts of slag, 3 parts of lime and 10 parts of water and mix them evenly. Then add the 7 parts of water glass obtained in step 2 and mix evenly to obtain a slurry.
[0067] Step 4: The obtained slurry is molded at 15 MPa to obtain standard bricks. Then, the standard bricks are subjected to hydrothermal reaction at 195℃ and 1.2 MPa to obtain hydrothermal bricks.
[0068] Comparative Example 2
[0069] Step 1: Take another 60 parts of humus, 20 parts of slag, 8 parts of lime and 10 parts of water and mix them evenly to obtain a slurry;
[0070] Step 2: The obtained slurry is molded at 15 MPa to obtain standard bricks. Then, the standard bricks are subjected to hydrothermal reaction at 195℃ and 1.2 MPa to obtain hydrothermal bricks.
[0071] The heavy metal ions and their contents in the humus soil of the landfill were tested, and the test results are shown in Table 1.
[0072] Table 1. Test results of heavy metal ions and their contents in humus soil from landfills.
[0073] heavy metal Pb Cr Cd Hg content 0.55 mg / L 0.67 mg / L 0.45 mg / L 0.6 mg / L
[0074] The performance of the hydrothermal bricks prepared in the examples and comparative examples was tested, and the test results are shown in Table 2.
[0075] The content of heavy metal ions after treatment was determined by crushing and grinding 20g of hydrothermal brick, adding it to 10ml of water, letting it stand for 30 days, and then taking the supernatant to test the heavy metal content.
[0076] Table 2 Performance test results of water-heated bricks
[0077]
[0078] The test results above show that the hydrothermal bricks prepared by the method of the present invention have high compressive strength, indicating that the hydrothermal bricks prepared by the method of the present invention have good mechanical properties. However, in Comparative Example 1, due to the unsuitable proportion of the added raw materials, the added water glass could not crosslink and gel well, resulting in poor fixation of heavy metals. The hydrothermal bricks prepared in Comparative Example 2 were easily leached after long-term use, causing secondary pollution. In Comparative Example 2, the landfill humus soil was not treated before being used to prepare hydrothermal bricks. The organic matter in the humus soil would hinder hydration and gelation, resulting in poor mechanical properties of the prepared hydrothermal bricks. Furthermore, after long-term use, heavy metal ions were easily leached, causing secondary pollution.
[0079] The hydrothermal bricks prepared by this invention can be applied to building exterior wall insulation, interior wall partitions, ground insulation, basement waterproofing and insulation, and building envelope structures, etc.
Claims
1. A method for manufacturing hydrothermal bricks using landfill humus soil, characterized by, Includes the following steps: Step 1: After mixing humus with sodium salt, calcin the mixture, crush and grind it, add acid solution for acid leaching, separate the solid and liquid, and dry the resulting solid material to obtain a dry gel. Step 2: Add NaOH solution to the dry gel to dissolve it, and water glass is obtained; Step 3: Take humus, slag, lime, and water, mix them evenly, then add the water glass and mix evenly to obtain a slurry; the mass ratios of humus, slag, lime, water, and water glass in the slurry are 50-75wt%, 10-30wt%, 5-10wt%, 5-15wt%, and 4-10wt%, respectively. Step 4: The slurry is molded to obtain standard bricks. The standard bricks are then subjected to a hydrothermal reaction to obtain hydrothermal bricks. The hydrothermal reaction is carried out under high temperature and high pressure, with a temperature of 180-210℃ and a pressure of 1.2-1.3MPa. The hydrothermal reaction time is at least 10 hours.
2. The method for manufacturing hydrothermal bricks using landfill humus soil according to claim 1, wherein, The sodium salt mentioned in step 1 is selected from at least one of sodium carbonate, sodium sulfate, sodium nitrate and sodium chloride, and the amount of sodium salt added is 15%-50% of the total mass of humus and sodium salt.
3. The method for preparing hydrothermal bricks using landfill humus as described in claim 1, characterized in that, The calcination temperature in step 1 is 800-1100℃, and the calcination time is 2-4 hours.
4. The method for manufacturing hydrothermal bricks using landfill humus soil according to claim 1, wherein the landfill humus soil is mixed with the cement at a ratio of 1:1 to 1:
3. 5 The concentration of the acid solution mentioned in step 1 is 5-10 mol / L, and the amount added is according to a solid-liquid ratio of 1:5-1:
10.
5. The method for preparing hydrothermal bricks using landfill humus as described in claim 1, characterized in that, The drying temperature in step 1 is 50-100℃, and the drying time is 2-5 hours.
6. The method for preparing hydrothermal bricks using landfill humus as described in claim 1, characterized in that, The concentration of the NaOH solution in step 2 is 1%-10%, and the amount added is 3-5 times the mass of the dry gel.
7. The method for preparing hydrothermal bricks using landfill humus as described in claim 1, characterized in that, The compression molding pressure in step 4 is 10-20 MPa.
8. A hydrothermal brick, said hydrothermal brick being prepared by the method according to any one of claims 1 to 7.