A method for preparing ball soil by resource utilization of granite weathered gravel-like urban engineering slag

Abstract

The present application relates to the technical field of ball soil materials, and specifically provides a method for preparing ball soil by resource utilization of weathered granite gravel-like urban engineering slag, the steps of which include: S1, preparing a first coarse slurry from the urban engineering slag, removing sand and impurities, grinding it to a 1 μm sieving rate of no more than 10%, and removing iron by magnetic separation to obtain a kaolin slurry; S2, adding bentonite, montmorillonite, pyrophyllite and organic matter into water to prepare a second coarse slurry, grinding it to a 20 μm sieving rate of no more than 10%, and a 10 μm sieving rate of no more than 10%, to obtain an auxiliary material slurry; S3, mixing the kaolin slurry and the auxiliary material slurry, and stirring them evenly to obtain a mixed slurry, adding a flocculant for flocculation, filter pressing, and drying to obtain ball soil. The ball soil of the present application has the characteristics of high plasticity and dry strength, as well as fast grouting speed and dehydration speed.

Description

Technical Field

[0001] The present application relates to the technical field of ball soil materials, and in particular to a method for preparing ball soil by resource-utilizing weathered granite gravel-like urban engineering debris. Background Art

[0002] Modern urban construction generates a large amount of urban construction waste, one type of which is weathered granite gravel. This waste is typically disposed of by landfill, which not only occupies a large amount of land but also poses numerous safety concerns. Weathered granite gravel urban construction waste typically contains kaolin, a valuable mineral resource, as well as potassium feldspar and mica.

[0003] Ball clay is primarily composed of kaolin, supplemented with a certain amount of bentonite, quartz, montmorillonite, and other organic materials. Therefore, ball clay exhibits greater plasticity than kaolin and is a key raw material for ceramic production, improving the forming properties of greenware. Extracting kaolin from urban construction waste and combining it with bentonite, montmorillonite, pyrophyllite, and other organic materials to create ball clay is an effective method for transforming waste into valuable resources. Summary of the Invention

[0004] The properties of ball clay have a significant impact on its application. For example, in ceramics, achieving better plasticity and dry strength in porcelain clay requires a smaller particle size. However, increasing the particle size of the ball clay to meet the requirements for rapid pouring, accelerated grouting, and dehydration speeds presents a conflicting requirement. To address these technical challenges, the present application provides a method for preparing ball clay by utilizing weathered granite gravel-like urban engineering waste as a resource.

[0005] This application adopts the following technical solutions:

[0006] A method for preparing ball soil by resource utilization of weathered granite gravel-like urban engineering debris, comprising the following steps:

[0007] S1. After the urban engineering slag is prepared into a first coarse slurry, sand and impurities are removed, and the slurry is ground to a 1 μm sieve residue rate of no more than 10%, and iron is removed by magnetic separation to obtain a kaolin slurry;

[0008] S2. Add bentonite, montmorillonite, pyrophyllite and organic matter into water to prepare a second coarse slurry, and grind it until the 20 μm sieve residue rate is no more than 10% and the 10 μm sieve residue rate is no more than 10%, to obtain an auxiliary material slurry;

[0009] S3. Mix the kaolin slurry described in step S1 and the auxiliary material slurry described in step S2, and stir them evenly to obtain a mixed slurry, add a flocculant to flocculate, filter press, and dry to obtain ball clay.

[0010] Preferably, the concentration of the first coarse slurry in step S1 is 3-20 wt%.

[0011] Preferably, in step S1, a first grinding aid is added to the first coarse slurry after sand and impurities are removed, and the first grinding aid is selected from one or more of glycerol, ethylene glycol, triisopropanolamine, triethanolamine and tri-n-butanolamine.

[0012] More preferably, the weight of the first grinding aid is 0.5-3% of the weight of the first coarse slurry.

[0013] Preferably, the weight ratio of bentonite, montmorillonite, pyrophyllite and organic matter in step S2 is 1:0-0.2:0-0.2:0.1-0.4.

[0014] Preferably, the particle sizes of the bentonite, montmorillonite and pyrophyllite in step S2 are not less than 50 mesh.

[0015] Preferably, the concentration of the second coarse slurry in step S2 is 3-20 wt%.

[0016] Preferably, in step S2, before grinding the second coarse slurry, 0.3-3% of the weight of the second coarse slurry is added to the second grinding aid, and the second grinding aid is selected from one or more of glycerol, ethylene glycol, triisopropanolamine, triethanolamine and tri-n-butanolamine.

[0017] Preferably, the flocculant in step S3 is selected from polyacrylamide.

[0018] Preferably, the weight ratio of the kaolin slurry to the auxiliary material slurry in step S3 is 1-20:1.

[0019] In summary, this application has the following beneficial effects:

[0020] 1. This application prepares kaolin slurry with finer particle size and auxiliary material slurry with coarser particle size respectively. The fine kaolin particles in the prepared ball clay are wrapped on the surface of the coarse particles of the auxiliary slurry. The prepared ball clay has good plasticity and drying strength, as well as the characteristics of fast grouting speed and fast dehydration speed, which solves the contradictions existing in the existing ball clay.

[0021] 2. In this application, the kaolin slurry with finer particle size and the auxiliary material slurry with coarser particle size form a ball soil with a structure in which fine kaolin particles wrap coarse slurry particles, and organic matter further wraps fine kaolin particles and coarse particles. The plasticity and dry strength characteristics of the ball soil are mainly provided by kaolin and organic matter, and the fast grouting speed and dehydration speed characteristics are mainly provided by bentonite, montmorillonite and pyrophyllite in the auxiliary slurry, so it can have better comprehensive performance.

[0022] 3. The inventors found that the purpose of the invention can only be achieved when the particle size difference between the finer kaolin slurry and the coarser auxiliary material slurry is within a certain range, so that the ball clay has both good plasticity and dry strength, as well as fast grouting speed and dehydration speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Attachment Figure 1 A schematic diagram of the ball soil structure of this application;

[0024] Among them, 1-kaolin fine particles, 2-organic matter, 3-slurry coarse particles. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below.

[0026] Throughout this specification, unless otherwise specified, the terms used herein should be understood as having the same meaning as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the event of any conflict, the present specification shall take precedence.

[0027] The present application provides a method for preparing ball soil by resource utilization of weathered granite gravel-like urban engineering debris, comprising the following steps:

[0028] S1. After the urban engineering slag is prepared into a first coarse slurry, sand and impurities are removed, and the slurry is ground to a 1 μm sieve residue rate of no more than 10%, and iron is removed by magnetic separation to obtain a kaolin slurry;

[0029] S2. Add bentonite, montmorillonite, pyrophyllite and organic matter into water to prepare a second coarse slurry, and grind it until the 20 μm sieve residue rate is no more than 10% and the 10 μm sieve residue rate is no more than 10%, to obtain an auxiliary material slurry;

[0030] S3. Mix the kaolin slurry in step S1 and the auxiliary material slurry in step S2, and stir them evenly to obtain a mixed slurry, add a flocculant to flocculate, filter press, and dry to obtain ball clay.

[0031] In this application, the sieving rate refers to the percentage of the weight of the residue on the sieve to the total weight of the material after the material is sieved. The screening rate refers to the percentage of the weight of the material passing through the sieve to the total weight of the material after the material is sieved.

[0032] In order to resolve the contradictions existing in the existing technology of ball clay, the present application adopts a method of combining fine-grained kaolin and coarse-grained auxiliary material particles. Through the selection and configuration of particle size, after the ball clay is formed by mixing, the kaolin can be wrapped on the surface of the auxiliary material particles. The fine-grained kaolin and organic matter provide the ball clay with good plasticity and dry strength, and the coarse-grained auxiliary material particles provide fast grouting speed and dehydration speed.

[0033] In step S1 of the present application, magnetic separation and iron removal adopts superconducting magnetic separation or high gradient magnetic separation, etc. In the present application, there is no particular limitation on organic matter, including but not limited to lignite, humic acid, peat, etc.

[0034] In a preferred embodiment of the present application, the concentration of the first coarse slurry in step S1 is 3-20 wt%. The concentration of the first coarse slurry is within the above range, which is relatively suitable. For example, the concentration of the first coarse slurry can be 3 wt%, 5 wt%, 7 wt%, 10 wt%, 13 wt%, 15 wt%, 18 wt%, 20 wt%, etc.

[0035] In a preferred embodiment of the present application, a first grinding aid is added to the first coarse slurry after sand and impurities are removed in step S1. The first grinding aid is selected from one or more of glycerol, ethylene glycol, triisopropanolamine, triethanolamine, and tri-n-butanolamine. Adding the first grinding aid helps improve grinding efficiency and shorten grinding time. Furthermore, the weight of the first grinding aid is 0.5-3% of the weight of the first coarse slurry. For example, the weight of the first grinding aid can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, etc., of the weight of the first coarse slurry.

[0036] In a preferred embodiment of the present application, the weight ratio of bentonite, montmorillonite, pyrophyllite, and organic matter in step S2 is 1:0-0.2:0-0.2:0.1-0.4. In the present application, the coarse particles are mainly bentonite, which can be supplemented with montmorillonite and / or pyrophyllite. The added organic matter can improve the plasticity and dry strength of the ball soil.

[0037] In a preferred embodiment of the present application, the particle size of the bentonite, montmorillonite and pyrophyllite in step S2 is no less than 50 mesh. The particle size of the bentonite, montmorillonite and pyrophyllite is relatively large, which is conducive to obtaining relatively coarse particles after grinding. Further, the particle size of the bentonite, montmorillonite and pyrophyllite is no more than 10 mesh.

[0038] In a preferred embodiment of the present application, the concentration of the second coarse slurry in step S2 is 3-20 wt%. The concentration of the second coarse slurry is within the above range, which is relatively suitable. For example, the concentration of the second coarse slurry can be 3 wt%, 5 wt%, 7 wt%, 10 wt%, 13 wt%, 15 wt%, 18 wt%, 20 wt%, etc.

[0039] In a preferred embodiment of the present application, a second grinding aid of 0.3-3% by weight of the second coarse slurry is added before grinding the second coarse slurry in step S2, and the second grinding aid is selected from one or more of propylene glycol, ethylene glycol, triisopropanolamine, triethanolamine and tri-n-butanolamine. Adding the second grinding aid helps to improve the grinding efficiency, shorten the grinding time, and obtain coarse particles with a particle size within a certain range, such as the above-mentioned 20μm sieving rate does not exceed 10%, and the 10μm sieving rate is not higher than 10%. Taking the 20μm sieving rate of 10% and the 10μm sieving rate of 10% as an example, the D of the auxiliary material slurry is 10 Particle size is 10 μm, D 90 The particle size is 20 μm, D 50 There is no special limitation, and it can be 14μm, 15μm, etc.; or taking the sieve rate of 20μm as 8% and the sieve rate of 10μm as 5% as an example, the D5 particle size of the auxiliary material slurry is 10μm, and D 92 The particle size is 20 μm, D 50 There is no particular limitation, and the particle size can be 14 μm, 15 μm, 16 μm, etc. In the present application, if after grinding, the sieve residue rate of particles that do not reach 20 μm does not exceed 10%, and the sieve rate of particles that pass 10 μm does not exceed 10%, for example, if the sieve rate of particles that pass 10 μm is higher than 10%, some particles with a particle size lower than 10 μm can be sieved out first.

[0040] In a preferred embodiment of the present application, the flocculant in step S3 is selected from polyacrylamide, and its weight is 0.1-1% of the weight of the mixed slurry.

[0041] In a preferred embodiment of the present application, the weight ratio of the kaolin slurry to the auxiliary material slurry in step S3 is 1-20:1. Further, the weight ratio of the kaolin slurry to the auxiliary material slurry is 1-10:1. For example, the weight ratio can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc. Further, the weight ratio of the kaolin slurry to the auxiliary material slurry can be 1-3:1.

[0042] The technical solution of the present application is described in detail below with reference to the embodiments and comparative examples. The granite weathered gravel urban engineering slag in the present application was obtained from the slag excavated during the construction of the Jimei Avenue subway in Jimei District, Xiamen City.

[0043] Example 1

[0044] The urban engineering slag was prepared into a first coarse slurry with a concentration of 10wt%, and the sand and impurities were removed. The sieving rate of 1μm was ground by ball milling to 9%. The iron was removed by high gradient magnetic separation to obtain kaolin slurry. The concentration of the kaolin slurry was measured to be 6.7wt%. Bentonite, montmorillonite and pyrophyllite with a particle size of 20-33 mesh, and lignite were added to water in a weight ratio of 1:0.1:0.15:0.3 to prepare a second coarse slurry with a concentration of 12wt%. The slurry was ground by ball milling. After grinding, it was found that the sieving rate of 20μm was 8%, and the sieving rate of 10μm was 12%. The ground slurry was sieved with a 10μm sieve to remove some particles with a particle size below 10μm, so that the sieving rate of 10μm was 9%, and the auxiliary material slurry was obtained.

[0045] The kaolin slurry and the auxiliary material slurry are mixed in a weight ratio of 1:1 to obtain a mixed solution, and the mixture is stirred evenly. 0.2% of the weight of the mixed solution of polyacrylamide flocculant is added for flocculation, filter pressing, and drying to obtain ball soil.

[0046] Example 2

[0047] The difference between Example 2 and Example 1 is that in Example 1, triethanolamine, a grinding aid, was added to the second coarse slurry at a concentration of 1% by weight of the second coarse slurry before grinding. After grinding, the 20 μm sieve retention rate was 9% and the 10 μm sieve retention rate was 8%. Screening of the ground slurry was no longer necessary. The remaining steps remained unchanged.

[0048] Example 3

[0049] Example 3 differs from Example 1 in that the weight ratio of bentonite, montmorillonite, pyrophyllite, and organic matter in Example 1 was adjusted from 1:0.1:0.15:0.3 to 1:0:0:0.3. After grinding, the 20 μm sieve retention rate was 9%, and the 10 μm sieve retention rate was 14%. The ground slurry was sieved using a 10 μm sieve to remove particles with a diameter less than 10 μm, resulting in a 10 μm sieve retention rate of 10%. The remaining steps remained unchanged.

[0050] Example 4

[0051] Example 4 differs from Example 1 in that the weight ratio of bentonite, montmorillonite, pyrophyllite, and organic matter in Example 1 was adjusted from 1:0.1:0.15:0.3 to 1:0.1:0:0.3. After grinding, the 20 μm sieve retention rate was 10%, and the 10 μm sieve retention rate was 12%. The ground slurry was sieved using a 10 μm sieve to remove particles with a diameter less than 10 μm, resulting in a 10 μm sieve retention rate of 9%. The remaining steps remained unchanged.

[0052] Example 5

[0053] Urban construction waste soil was prepared into a first coarse slurry with a concentration of 15 wt %. After sand and impurities were removed, 1 wt % of the first coarse slurry weight of glycerol was added as a grinding aid. The slurry was ball milled to a 1 μm sieve residue rate of 10%. The slurry was demagnetized using a superconducting magnetic separator to obtain a kaolin slurry with a measured concentration of 10.3 wt %.

[0054] Bentonite, montmorillonite, and pyrophyllite with particle sizes of 20-33 mesh, along with peat, were added to water in a weight ratio of 1:0.1:0.1:0.4 to prepare a second coarse slurry with a concentration of 15 wt%. Triisopropanolamine, a grinding aid, was added at a concentration of 0.8% by weight of the second coarse slurry, and the mixture was ground using a ball mill. After grinding, the 20 μm sieve retention rate was 8%, and the 10 μm sieve retention rate was 10%, thereby obtaining an auxiliary material slurry.

[0055] The kaolin slurry and the auxiliary material slurry were mixed in a weight ratio of 3:1, stirred evenly to obtain a mixed solution, and 0.3% of the weight of the mixed solution of polyacrylamide flocculant was added for flocculation, filter pressing, and drying to obtain ball soil.

[0056] Example 6

[0057] The difference between Example 6 and Example 5 is that in Example 5, the weight ratio of bentonite, montmorillonite, pyrophyllite and peat was adjusted from 1:0.1:0.1:0.4 to 1:0.1:0.1:0.1. The other steps remained unchanged.

[0058] Example 7

[0059] The difference between Example 7 and Example 5 is that in Example 5, the weight ratio of kaolin slurry to auxiliary material slurry was adjusted from 3:1 to 5:1. The other steps remained unchanged.

[0060] Example 8

[0061] The difference between Example 8 and Example 5 is that in Example 5, the weight ratio of kaolin slurry to auxiliary material slurry was adjusted from 3:1 to 10:1. The other steps remained unchanged.

[0062] Comparative Example 1

[0063] The difference between Comparative Example 1 and Example 5 is that in Example 5, after ball milling, the 1 μm sieve residue rate of the auxiliary material slurry is 9%. The other steps remain unchanged.

[0064] Comparative Example 2

[0065] The difference between Comparative Example 2 and Example 5 is that in Example 5, after ball milling, the 5 μm sieve residue rate of the auxiliary material slurry is 10%, and the 1 μm sieve residue rate is 9%. The other steps remain unchanged.

[0066] Comparative Example 3

[0067] The difference between Comparative Example 3 and Example 5 is that in Example 5, after ball milling, the 10 μm sieve residue of the kaolin slurry is 9%. The remaining steps remain unchanged.

[0068] Comparative Example 4

[0069] The difference between Comparative Example 4 and Example 5 is that in Example 5, after ball milling, the 20 μm sieve residue rate of the kaolin slurry is 11%. The remaining steps remain unchanged.

[0070] Comparative Example 5

[0071] The difference between Comparative Example 5 and Example 5 is that in Example 5, the weight ratio of kaolin slurry to auxiliary material slurry was adjusted from 3:1 to 0.5:1. The other steps remained unchanged.

[0072] Performance test methods and results

[0073] Plasticity index: tested according to JB / T5893.5-1991.

[0074] Dry strength: The ball soil to be tested is made into a 100mm×10mm×10mm test bar using a plaster mold. The test bar is placed on a support with a span of 60mm. The data of the test bar when it is bent is measured using an electronic universal testing machine.

[0075] Fluidity: Add water to the ball soil to be tested to a concentration of 80 wt% to prepare a dispersion. Fill a 100 mL viscometer with the dispersion. While opening the outlet, press the stopwatch and record the time it takes for the dispersion to flow out. The shorter the time, the better the fluidity and the faster the grouting speed.

[0076] Dehydration rate: Using the gypsum crucible method, a gypsum crucible (8 cm high, 4 cm inner diameter, 3 cm wall thickness) was made with fried hemihydrate gypsum and dried at 70°C; the ball soil to be tested was added with water to a concentration of 70 wt% to prepare a dispersion, which was injected into the crucible to a height of 6 cm. The dispersion was allowed to stand for 30 minutes, and the height H1 of the dispersion was measured. Five parallel tests were performed, and the average value was calculated as follows: The dehydration rate calculation formula is (6-H1) / 30.

[0077] The results are shown in Table 1 below.

[0078] Table 1 Performance test results

[0079]

[0080] As can be seen from the data in Table 1 above, for preparing ball soil from granite weathered gravel-like urban engineering slag, if the particle size of kaolin particles and other particles such as bentonite in the ball soil is relatively close, when the particle size is relatively small, the plasticity and drying strength of the ball soil are higher, but the fluidity and dehydration rate are relatively poor. When the particle size is relatively large, the fluidity and dehydration rate of the ball soil are relatively good, but the plasticity and drying strength deteriorate. The present application adopts kaolin particles and other particles such as bentonite with different particle size combinations, and the prepared ball soil can have good plasticity, drying strength, fluidity and dehydration rate, and has better overall performance. Comparative Example 5 and Comparative Example 2 show that the particle size difference between kaolin particles and other particles such as bentonite is within a suitable range, so as to obtain ball soil with better overall performance. Comparative Example 5 and Comparative Example 5 show that when the kaolin content in the ball soil is insufficient, both plasticity and drying strength deteriorate.

[0081] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for preparing ball soil by utilizing granite weathered gravel-like urban engineering slag as a resource, characterized in that the steps include: S1. Weathered granite gravel-like urban engineering slag is prepared into a first coarse slurry, after which sand and impurities are removed, and the slurry is ground to a 1 μm sieve residue rate of no more than 10%, and iron is removed by magnetic separation to obtain a kaolin slurry; S2, adding bentonite, montmorillonite, pyrophyllite and organic matter into water to prepare a second coarse slurry, grinding until the 20 μm sieve residue rate is no more than 10%, and the 10 μm sieve rate is no more than 10%, to obtain an auxiliary material slurry, wherein the weight ratio of the bentonite, montmorillonite, pyrophyllite and organic matter is 1:0-0.2:0-0.2:0.1-0.4; S3. Mix the kaolin slurry described in step S1 and the auxiliary material slurry described in step S2, and stir them evenly to obtain a mixed slurry, add a flocculant to flocculate, filter press, and dry to obtain ball clay, wherein the weight ratio of the kaolin slurry to the auxiliary material slurry is 1-20:

1.

2. The method for preparing ball soil by resource utilization of granite weathered gravel-like urban engineering debris according to claim 1, characterized in that: The concentration of the first coarse slurry in step S1 is 3-20 wt %.

3. The method for preparing ball soil by resource utilization of granite weathered gravel-like urban engineering debris according to claim 1, characterized in that: In step S1, after the first coarse slurry is desanded and impurities removed, a first grinding aid is added, wherein the first grinding aid is selected from one or more of glycerol, ethylene glycol, triisopropanolamine, triethanolamine and tri-n-butanolamine.

4. The method for preparing ball soil by resource utilization of granite weathered gravel-like urban engineering debris according to claim 3, characterized in that: The weight of the first grinding aid is 0.5-3% of the weight of the first coarse slurry.

5. The method for preparing ball soil by resource utilization of granite weathered gravel-like urban engineering debris according to claim 1, characterized in that: The particle sizes of the bentonite, montmorillonite and pyrophyllite in step S2 are not less than 50 mesh.

6. The method for preparing ball soil by resource utilization of granite weathered gravel-like urban engineering debris according to claim 1, characterized in that: The concentration of the second coarse slurry in step S2 is 3-20 wt %.

7. The method for preparing ball soil by resource utilization of granite weathered gravel-like urban engineering debris according to claim 1, characterized in that: In step S2, before grinding the second coarse slurry, 0.3-3% of the weight of the second coarse slurry is added to the second grinding aid, and the second grinding aid is selected from one or more of glycerol, ethylene glycol, triisopropanolamine, triethanolamine and tri-n-butanolamine.

8. The method for preparing ball soil by resource utilization of weathered granite gravel-like urban engineering debris according to claim 1, characterized in that: The flocculant in step S3 is selected from polyacrylamide.

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