Method for treating slope of dam body of refuse landfill by using concentrated solution sludge

Abstract

The invention relates to a method for treating a slope by using concentrated solution sludge. A dam body repairing material is formed by using concentrated solution sludge, is mixed with soil and rocks cleaned from a dam body, and is sprayed to a side slope, so that the side slope is quickly treated. The method can effectively treat the slope of the refuse landfill, has the advantages of being simple and easy to implement, low in investment, environmentally friendly, easy and convenient to construct and short in construction period, and meanwhile has large application and popularization value and remarkable economic and social benefits.

Description

[0001] The invention belongs to the technical field of solidification / stabilization, and more specifically, relates to a method for treating a landfill dam slope with concentrated liquid sludge. Background Art

[0002] Landslide is a process and phenomenon in which the local stability of the slope is destroyed. Under the action of gravity, the rock or soil slides as a whole along one or more broken sliding surfaces, posing a hidden danger to road safety. There are many factors that cause landslides. The geological structure and physical and mechanical properties of the slope are the internal factors that determine its stability. Precipitation, changes in groundwater levels, and human activities are external factors that affect slope stability. At present, the commonly used slope management method is grouting to form piles connecting the landslide and the slope. However, landslides inherently have a sliding tendency. The arrangement of pile positions, drilling and grouting, and grouting operations will affect the stability of the slope, which is likely to cause sliding during the construction process, endangering the safety of construction workers.

[0003] A new type of dam repair material is proposed. Traditional construction materials such as cement need to be transported from distant processing plants to the construction site, which does not meet the design principles of reducing earthwork transportation and using local materials. In addition, the use of a large amount of cement will consume a large amount of natural resources and emit a large amount of carbon dioxide, which is contrary to my country’s proposed "carbon peak and carbon neutrality" dual carbon national strategic deployment. Summary of the invention

[0004] A new type of dam repair material, the proportions of each component are as follows: concentrated liquid sludge 54%-61%, fly ash 11%-14%, waste incineration fly ash / bottom ash 15%-20%, and alkali-activated solution 12%-15%.

[0005] Preferably, the concentrated liquid sludge is taken from a domestic waste landfill, produced by an immersion combustion process, and is dark black and fluid; the properties of the concentrated liquid sludge are: water content is 26.76%; soil relative density is 2.31%; pH value is 9.31; natural density is 1.88g.cm-3; plastic limit is 9.62%; liquid limit is 19.18%; and organic matter content is 5.87 / %.

[0006] Preferably, the components of the concentrated sludge are: Na2O is 35.08%; Cl is 28.14%; K2O is 17.05%; SO3 is 14.14%; MgO is 2.44%; CaO is 2.07%; SiO2 is 0.40%; Fe2O3 is 0.13%; P2O5 is 0.07%; Al2O3 is 0.48%

[0007] Preferably, the components of the fly ash are: CaO is 15.72%; SiO2 is 36.49%; SO3 is 2.38%; Al2O3 is 38.0%; Fe2O3 is 0.28%; MgO is 9.74%; Na2O is 0.54%; and K2O is 0.42%.

[0008] Preferably, the components of the waste incineration fly ash are: CaO is 33.00%; SiO2 is 14.85%; SO3 is 9.22%; Al2O3 is 3.83%; Fe2O3 is 2.21%; MgO is 3.17%; P2O5 is 1.39%; Na2O is 6.94%; K2O is 6.66%; and Cl is 14.08%.

[0009] Preferably, the components of the waste incineration ash are: CaO is 57.70%; SiO2 is 9.63%; SO3 is 5.19%; Al2O3 is 4.95%; Fe2O3 is 5.47%; MgO is 3.65%; P2O5 is 2.89%; Na2O is 2.25%; K2O is 1.25%; and Cl is 3.80%.

[0010] Preferably, the particle size of the fly ash and the waste incineration fly ash / bottom ash should be less than 0.075 mm, and the moisture content should be no higher than 3%.

[0011] A method for constructing a dam slope of a landfill using concentrated liquid sludge, comprising the following steps:

[0012] First, the dangerous blocks and soil on the slope are cleared; then, the cleared soil and rocks are crushed on site; they are then mixed with new dam repair materials and sprayed onto the slope to quickly and easily manage the slope.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The formula of the new dam repair material of the present invention is simple in composition, and the fly ash therein comes from idle or untreated industrial solid waste, and is mainly used in the treatment of residual mine waste such as tailings. The leachate sludge and garbage incineration by-products are directly derived from landfills. The overall transportation volume is small and easy to obtain, which meets the sustainable development requirements of "treating waste with waste" and has a low overall industrial cost.

[0015] 2. The concentrated liquid sludge in the new dam repair material of the present invention has the characteristic of extremely high salt content. Its soluble salt particles are easily dissolved in water and cause the skeleton of the solidified sample to collapse. The fly ash and bottom slag have high heavy metal content and are difficult to handle hazardous waste materials in landfills. After combining them to form a new dam repair material, not only the unconfined compressive strength and water stability can meet the construction requirements; through the leaching toxicity test, the fixation efficiency of heavy metal elements in the fly ash and bottom slag of this solidified body reaches more than 99%, which well achieves the goal of "co-treatment" of hazardous waste / solid waste of waste incineration by-products and concentrated liquid sludge.

[0016] 3. The present invention provides a new solution to the problem of old dam slope management, and can be used to design expansion plans for different landfills. The plan is simple and easy to understand, and the construction difficulty is simple. DETAILED DESCRIPTION

[0017] The novel dam body repairing material of the invention comprises 54%-61% of concentrated liquid sludge, 11%-14% of fly ash, 15%-20% of fly ash / bottom slag from garbage incineration, and 12%-15% of alkali-activated solution.

[0018] The concentrated liquid sludge is taken from a domestic waste landfill and is produced by an immersion combustion process. It is dark black and fluid. Its basic physical properties are shown in Table 1, and its elemental composition is shown in Table 2. It can be seen that the concentrated liquid sludge is mainly composed of three soluble salts, and the content is very high, and it is easy to disintegrate when exposed to water.

[0019]

[0020] Table 1 Basic physical properties of concentrated liquid sludge

[0021] Element <![CDATA[Na2O]]> Cl <![CDATA[K2O]]> <![CDATA[SO3]]> MgO CaO <![CDATA[SiO2]]> <![CDATA[Fe2O3]]> <![CDATA[P2O5]]> <![CDATA[Al2O3]]> Mass content / % 35.08 28.14 17.05 14.14 2.44 2.07 0.40 0.13 0.07 0.48

[0022] Table 2 Elemental composition of concentrated sludge

[0023] Ag Ba Be Cd Cr Cu Ni Pb Zn Not detected 18 Not detected Not detected 4 Not detected 18 Not detected Not detected

[0024] Table 3 Heavy metal content of concentrated sludge

[0025] The concentrated liquid sludge is produced by reverse osmosis membrane filtration and submerged combustion process of leachate sludge from a domestic waste landfill, and will inherit some heavy metal elements of the leachate sludge during the formation process. The test results of its heavy metal content are shown in Table 3. It can be seen from Table 3 that the heavy metal content of the concentrated liquid sludge is extremely low, far below the control standard.

[0026] The particle size of the waste incineration bottom ash is less than 75 μm, the CaO content is ≥50%, the SiO2 content is ≥5%, and the Fe2O3 content is ≥5%. The particle size of the waste incineration fly ash is less than 75 μm, the CaO content is ≥30%, the SiO2 content is ≥10%, and the Cl content is ≥10%. The components of the three raw materials in the cementitious material are shown in Table 4, Table 5, and Table 6.

[0027] On the whole, all three raw materials contain relatively rich Ca, Si and Al elements and aluminosilicate minerals, and can be used as raw materials for cementitious materials.

[0028] type CaO <![CDATA[SiO2]]> <![CDATA[SO3]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> MgO <![CDATA[Na2O]]> <![CDATA[K2O]]> other Mass content / % 15.72 34.77 2.38 38.00 0.28 6.74 0.54 0.42 1.15

[0029] Table 4 Elemental composition of fly ash

[0030] Element <![CDATA[SiO2]]> <![CDATA[Al2O3]]> CaO <![CDATA[Fe2O3]]> <![CDATA[TiO2]]> <![CDATA[K2O]]> MgO <![CDATA[SO3]]> <![CDATA[Na2O]]> other Mass content / % 45.8 45.5 2.7 2.5 1.5 0.8 0.6 0.4 0.1 0.1

[0031] Table 5 Elemental composition of waste incineration ash

[0032] type CaO <![CDATA[SiO2]]> <![CDATA[SO3]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> MgO <![CDATA[P2O5]]> <![CDATA[Na2O]]> <![CDATA[K2O]]> Cl other Mass content / % 33.00 14.85 9.22 3.83 2.21 3.17 1.39 6.94 6.66 14.08 4.65

[0033] Table 6 Elemental composition of waste incineration fly ash

[0034] The alkaline excitation solution is prepared by adding Na2SiO3 with a modulus of 2.3 and a NaOH solution of the same mass with a concentration of 8 mol / L.

[0035] Example 2

[0036] According to the sample plan, the corresponding fly ash and waste incineration fly ash powders are weighed according to 57% concentrated liquid sludge, 12% fly ash, 17% waste incineration fly ash and 14% alkali-activated solution per kilogram of new dam repair material. After mixing and stirring until uniform, they are added to the concentrated liquid sludge. Then, the alkali-activated solution prepared in advance is added to the mixture of the alkali-activated raw material and the concentrated liquid sludge. First, stir at a speed of 62±5r / min for 2min, and then stir at a speed of 126±10r / min for 2min to form a uniform mixed slurry. The mixed slurry is transferred into a cylindrical PVC mold (39.1mm×80mm) in three layers, and vibrated on a vibration test bench for 2min to eliminate the air remaining inside the sample. It is demolded after curing for 24h in a standard curing room (temperature 20℃, humidity 98%), and continued to be cured for 28d. After the curing is completed, the unconfined compressive strength test, water stability test and leaching toxicity analysis are measured.

[0037] Test results: The unconfined compressive strength can reach 14.9Mpa, and the 28d water stability can reach 2.5Mpa and tends to be stable as the immersion time remains unchanged.

[0038] Example 3

[0039] The waste incineration fly ash in Example 2 was replaced with waste incineration bottom ash, and made into cylindrical specimens according to the same method. The specimens were cured in a standard curing room (temperature 20°C, humidity 98%) for 24 hours, demolded, and continued to be cured for 28 days. After the curing was completed, the unconfined compressive strength test, water stability test, and leaching toxicity analysis were measured.

[0040] Test results: The unconfined compressive strength can reach 15.2Mpa, and the 28d water stability can reach 2.6Mpa and tends to be stable as the immersion time remains unchanged.

[0041] Since Examples 2 and 3 contain bottom slag and fly ash with high heavy metal content, it is necessary to conduct leaching toxicity analysis on them. The test results are shown in Table 7, which shows that in the new dam repair material, the toxicity is far below the standard limit; that is, in the new dam repair material of the present invention, the toxicity in the bottom slag and fly ash can be effectively reduced.

[0042] Example 4

[0043] A method for constructing a dam slope of a landfill using concentrated liquid sludge, the specific method is as follows:

[0044] S1. Remove the dangerous soil on the slope and perform simple crushing.

[0045] S2. Mix the soil blocks obtained in step 1 with the new dam repair material at a ratio of 1:1.

[0046] S3. Mix at the nozzle and spray onto the slope surface.

[0047] S4. After the slope is stable, the next slope treatment can be carried out.

[0048] The above is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited to the above content. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A new type of dam repair material, characterized in that: The proportions of each component are: concentrated liquid sludge 54%-61%, fly ash 11%-14%, waste incineration fly ash / bottom ash 15%-20%, and alkali-activated solution 12%-15%.

2. The new dam repair material according to claim 1 is characterized in that: The concentrated liquid sludge is taken from a domestic waste landfill and is produced by an immersion combustion process. It is dark black and fluid. The properties of the concentrated liquid sludge are as follows: water content is 26.76%; soil relative density is 2.31%; pH value is 9.31; natural density is 1.88g.cm-3; plastic limit is 9.62%; liquid limit is 19.18%; and organic matter content is 5.87 / %.

3. The new dam repair material according to claim 2 is characterized in that: The components of the concentrated liquid sludge are: Na2O is 35.08%; Cl is 28.14%; K2O is 17.05%; SO3 is 14.14%; MgO is 2.44%; CaO is 2.07%; SiO2 is 0.40%; Fe2O3 is 0.13%; P2O5 is 0.07%; and Al2O3 is 0.48%.

4. The new dam repair material according to claim 1 is characterized in that: The components of the fly ash are: CaO is 15.72%, SiO2 is 36.49%, SO3 is 2.38%, Al2O3 is 38.0%, Fe2O3 is 0.28%, MgO is 9.74%, Na2O is 0.54% and K2O is 0.42%.

5. The novel dam repair material according to claim 1 is characterized in that: The components of the waste incineration fly ash are: CaO is 33.00%; SiO2 is 14.85%; SO3 is 9.22%; Al2O3 is 3.83%; Fe2O3 is 2.21%; MgO is 3.17%; P2O5 is 1.39%; Na2O is 6.94%; K2O is 6.66%; and Cl is 14.08%.

6. The novel dam repair material according to claim 1 is characterized in that: The components of the waste incineration ash are: CaO is 57.70%; SiO2 is 9.63%; SO3 is 5.19%; Al2O3 is 4.95%; Fe2O3 is 5.47%; MgO is 3.65%; P2O5 is 2.89%; Na2O is 2.25%; K2O is 1.25%; and Cl is 3.80%.

7. The novel dam repair material according to claim 1 is characterized in that: The particle size of the fly ash and the waste incineration fly ash / bottom ash must be less than 0.075 mm, and the moisture content must not be higher than 3%.

8. A method for constructing a landfill dam slope by using concentrated liquid sludge to treat the landfill, characterized in that: The following steps are involved: S1. Remove the dangerous soil on the slope and perform simple crushing. S2. Mix the soil blocks obtained in step 1 with the new dam repair material at a ratio of 1:

1. S3. Mix at the nozzle and spray onto the slope surface. S4. After the slope is stable, the next slope treatment can be carried out.

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