An integrated treatment method for dehydration, crushing and solidification of sand washing mud

Abstract

The present invention discloses an integrated treatment method for dehydration, crushing and solidification of sand washing mud. The method comprises mixing a conditioning agent with the sand washing mud, performing a dehydration and crushing treatment, mixing and stirring with a solidifying material, and then performing extrusion and vibration molding, and obtaining a sand washing mud-based solidified body after curing. The present invention uses polyacrylamide, polyaluminium chloride and fly ash / coal gasification slag as conditioning agents, and utilizes the electrical neutralization, adsorption bridging and netting effects of the conditioning agent to flocculate and precipitate the colloidal particles. At the same time, the fly ash / coal gasification slag plays a skeleton role, which can provide a drainage channel inside the sand washing mud and solve the problem of filter cake crushing, thus realizing the leap from "high pollution and low efficiency" to "resource utilization and high performance" in the treatment of sand washing mud, and combining the triple values ​​of process innovation, environmental protection compliance and economic feasibility, providing an efficient solution for the resource utilization of construction waste. At the same time, the present invention is suitable for multi-scenario building material applications such as roadbed materials, unburned bricks and artificial aggregates.

Description

Technical Field

[0001] The present invention relates to the technical field of sand washing mud treatment and utilization, and in particular to a sand washing mud dehydration, crushing and solidification integrated treatment method. Background Art

[0002] Sand washing mud is a waste product discharged during the wet production of manufactured sand. It typically consists of clay particles, silt, and water. According to statistics from the China Sand and Gravel Association, approximately 0.3 tons of sand washing mud is emitted for every ton of manufactured sand produced. Currently, large amounts of sand washing mud are dumped untreated, resulting in not only a waste of land resources but also environmental pollution of groundwater, soil, and air. Therefore, finding effective methods to render sand washing mud harmless, reduce its volume, stabilize it, and recycle it as a resource has become a pressing issue for the sand and gravel industry.

[0003] Washed sand sludge curing can effectively improve its physical and mechanical properties, enabling the cured material to meet diverse performance requirements. It has a wide range of applications, including road engineering, water conservancy projects, geotechnical engineering, and other fields. Currently, washed sand sludge curing mainly involves wet, dry, and semi-dry processes. Wet curing involves directly adding a curing agent to high-moisture-content washed sand sludge. This method is simple, low-cost, and highly efficient. However, due to the high moisture content, the cured product suffers from low mechanical strength and poor long-term stability. Dry curing involves mixing dried, dehydrated washed sand sludge with a curing agent to produce a cured product. This method produces a high-strength, relatively stable product, but at the expense of significantly increased cost and energy consumption. Semi-dry curing involves dehydrating the washed sand sludge to a preset target moisture content before mixing it with a curing agent. This method strikes a good balance between curing effectiveness, cost and energy consumption, and resource utilization potential, and is particularly aligned with the development trend of green building materials under the "dual carbon" goals.

[0004] In the semi-dry solidification treatment process of sand washing mud, the moisture content of sand washing mud plays a vital role, directly affecting the mixing uniformity and engineering performance of the solidified body. At present, the most common dehydration technology is to condition the sand washing mud by adding chemical flocculants, and then use a plate and frame filter press or a belt filter press for mechanical filter pressing and dehydration. However, the sand washing mud contains a large amount of fine particles. As the filter pressing and dehydration process proceeds, the fine particles gradually block the pores of the filter cake under the action of mechanical pressure, resulting in the inability to achieve deep dehydration of the sand washing mud. At the same time, high-pressure dehydration causes the filter cake particles to be densely packed, and the porosity is reduced to 20%-30% (the porosity of natural soil is about 40%-60%), which hinders the subsequent solidification treatment. Specifically, it manifests in: (1) the crushing energy consumption increases significantly because the dense filter cake requires additional mechanical crushing; (2) the uneven distribution of the solidifying agent easily forms an abnormal solidified body structure phenomenon of "surface hardening and internal looseness".

[0005] In summary, existing semi-dry solidification methods for sand washing mud suffer from core issues such as ineffective dehydration, high energy consumption for filter cake crushing, and uneven dispersion of the solidifying agent. Furthermore, current technologies often rely on single processes, lacking collaborative solutions, resulting in fragmented processes, high energy consumption, and low product value. Summary of the Invention

[0006] The purpose of the present invention is to provide an integrated treatment method for dehydration, crushing and solidification of sand washing mud, which can solve the problems encountered in the background technology, and can not only achieve efficient dehydration effect of sand washing mud in the early stage, but also achieve good crushing effect of filter cake after dehydration, and can also achieve solidification treatment of homogenized sand washing mud structure in the later stage.

[0007] To achieve the above object, the present invention provides an integrated treatment method for dehydration, crushing and solidification of sand washing mud, comprising the following steps:

[0008] S1. Mixing the conditioning agent and the sand washing mud to obtain conditioned sand washing mud;

[0009] S2, conveying the conditioned washed sand mud obtained in S1 to a plate and frame filter press for mechanical dehydration to obtain a deeply dehydrated washed sand mud filter cake;

[0010] S3, crushing the sand washing mud filter cake obtained in S2 through a mixer to obtain small sand washing mud particles;

[0011] S4, mixing the solidified material and the small particles of washed sand mud obtained in S3 uniformly through a mixer to obtain a mixture;

[0012] S5, placing the mixture obtained in S4 into a mold for extrusion and vibration molding to obtain a solidified body;

[0013] S6. The solidified body is transported to a curing room for curing to obtain a washed sand mud-based solidified body.

[0014] Preferably, in step S1, the water content of the sand washing mud is 90-96%, and the particle size of the sand washing mud is ≤0.15 mm.

[0015] Preferably, in step S1, the conditioning agent includes a chemical flocculant and a physical skeleton construct, the amount of the chemical flocculant added is 0-2.0 g / L, and the amount of the physical skeleton construct added is 0-40% of the dry mass of the sand washing mud. The specific steps of step S1 include:

[0016] S1-1. Add chemical flocculant into sand washing mud and stir for 5-10 minutes;

[0017] S1-2. Add the physical framework construct to the mixture in S1-1 and stir for 5-10 minutes.

[0018] Preferably, the chemical flocculant is a mixed solution of polyacrylamide and polyaluminum chloride, the mass ratio of polyacrylamide to polyaluminum chloride is 1:3~1:20, the physical skeleton structure is either fly ash or coal gasification slag; the polyacrylamide is an anionic polyacrylamide with a molecular weight of 12 million, the mass concentration of the polyacrylamide solution is 0.2wt%; the mass concentration of the polyaluminum chloride is 1.0wt%.

[0019] Preferably, in step S2, the moisture content of the sand washing mud filter cake is 25-30%, and the moisture content of the deep dehydrated filter cake is 8-12%.

[0020] Preferably, in step S3, the small particles of sand washing mud are particles with a particle size of less than 2.0 mm.

[0021] Preferably, in step S4, the curing material is sodium water glass, the modulus obtained after adjustment with sodium hydroxide is 1.5, the solid content is 42 wt%, and the addition amount of sodium water glass is 12-16 wt%.

[0022] Preferably, in step S5, the vibration time of the extrusion vibration molding is 10 s, the molding pressure is 10 MPa, and the holding time is 20 s.

[0023] Preferably, in step S6, the curing conditions are to cure the solidified body at a curing temperature of 80° C. and a curing humidity of 60% for 12 to 24 hours, and then transfer the cured body to a curing temperature of 20° C. and a curing humidity of 95% for further curing until the specified age.

[0024] The present invention uses polyacrylamide and polyaluminium chloride to mix with sand washing mud. Polyacrylamide and polyaluminium chloride can neutralize the electrical properties of colloidal particles and reduce the repulsive force between particles. At the same time, they also play an adsorption, bridging and netting role on the colloidal particles. Adjacent particles are connected to each other through polymer chains, which promotes particle flocculation and sedimentation. The skeleton constructs fly ash and coal gasification slag are rigid porous materials, which are evenly dispersed in the sand washing mud floc structure, providing channels for water discharge and reducing the moisture content of the sand washing mud. Compared with sand washing mud particles, fly ash and coal gasification slag particles have better sphericity, which can reduce friction between particles. At the same time, they effectively reduce the compressibility of the filter cake and alleviate the difficulty of filter cake crushing. Fly ash and coal gasification slag are rich in silicon and aluminum, and contain a certain amount of glass. Glass, as an amorphous phase with lattice defects, has strong chemical activity and is a substance that is conducive to alkali-induced reactions. In addition, fly ash / coal gasification slag can be used as a precursor of solidified materials to improve the strength of the solidified body.

[0025] Therefore, the present invention adopts the above-mentioned integrated treatment method of sand washing mud dehydration, crushing and solidification, which has the following beneficial effects:

[0026] (1) The method provided by the present invention effectively shortens the dehydration time of sand washing mud and greatly reduces the moisture content of sand washing mud.

[0027] (2) The present invention adds fly ash and coal gasification slag with spherical particles into the sand washing mud to reduce internal friction and compressibility, thereby achieving uniform crushing of the sand washing mud filter cake after dehydration.

[0028] (3) The solidified body of the present invention has a high degree of homogenization. By adding the solidified material in a slurry state and using a liquid activator, the homogenization degree of the solidified body is significantly improved, and the mechanical strength of the solidified body is effectively enhanced.

[0029] (4) The present invention organically combines the three processes of wet, dry and semi-dry to improve the processing efficiency and achieve integrated innovation of efficient dehydration, structural homogenization and stable solidification of sand washing mud.

[0030] The technical solution of the present invention is further described in detail below through examples. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further illustrated by the following examples.

[0032] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0033] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0034] Example 1:

[0035] This embodiment provides an integrated method for dehydrating, crushing, and solidifying sand washing mud, comprising the following steps:

[0036] (1) Evenly mix the sand washing mud and the conditioning agent: add 0.2 g / L polyacrylamide and 1.0 g / L polyaluminium chloride to the sand washing mud with a moisture content of 96% and stir for 5 minutes. Then add the skeleton structure fly ash to the sand washing mud in an amount of 20 wt% and stir for 10 minutes to complete the conditioning of the sand washing mud.

[0037] (2) Dehydration of sand washing mud: The conditioned sand washing mud is dehydrated by a plate and frame filter press to obtain a filter cake with a moisture content of 28%; the filter cake is further air-dried, and the moisture content of the filter cake after air drying is 10%.

[0038] (3) Filter cake crushing: The air-dried filter cake is crushed by a planetary mixer to obtain washed sand mud particles with a particle size of less than 2.0 mm.

[0039] (4) Raw material mixing: Add 12 wt% of solidified material to the crushed sand washing mud filter cake and stir for 5 minutes to obtain homogenized material.

[0040] (5) Extrusion vibration molding: The evenly mixed materials are placed into the molding machine for extrusion vibration molding to form a solidified body.

[0041] (6) Curing: Curing the solidified body at a curing temperature of 80°C and a curing humidity of 60% for 12 hours, and then transferring it to a curing temperature of 20°C and a curing humidity of 95% for further curing for 28 days.

[0042] Example 2:

[0043] This embodiment provides an integrated method for dehydrating, crushing, and solidifying sand washing mud, comprising the following steps:

[0044] (1) Evenly mix the sand washing mud and the conditioning agent: add 0.15g / L polyacrylamide and 1.5g / L polyaluminium chloride to the sand washing mud with a moisture content of 92%, stir for 5 minutes, then add the skeleton structure fly ash to the sand washing mud in an amount of 30wt% and stir for 10 minutes to complete the conditioning of the sand washing mud.

[0045] (2) Dehydration of sand washing mud: The conditioned sand washing mud is dehydrated by a plate and frame filter press to obtain a filter cake with a moisture content of 25%; the filter cake is further air-dried, and the moisture content of the filter cake after air drying is 8%.

[0046] (3) Filter cake crushing: The air-dried filter cake is crushed by a planetary mixer to obtain washed sand mud particles with a particle size of less than 2.0 mm.

[0047] (4) Raw material mixing: Add 16 wt% of solidified material to the crushed sand washing mud filter cake and stir for 5 minutes to mix the material evenly.

[0048] (5) Extrusion vibration molding: The evenly mixed materials are placed into the molding machine for extrusion vibration molding to form a solidified body.

[0049] (6) Curing: Curing the solidified body at a curing temperature of 80°C and a curing humidity of 60% for 12 hours, and then transferring it to a curing temperature of 20°C and a curing humidity of 95% for further curing for 28 days.

[0050] Example 3:

[0051] This embodiment provides an integrated method for dehydrating, crushing, and solidifying sand washing mud, comprising the following steps:

[0052] (1) The sand washing mud and the conditioning agent were evenly mixed: 0.2 / L polyacrylamide and 1.0g / L polyaluminium chloride were added to the sand washing mud with a moisture content of 90% and stirred for 5 minutes; then the skeleton structure coal gasification slag was added to the sand washing mud in an amount of 30wt% and stirred for 10 minutes to complete the conditioning of the sand washing mud.

[0053] (2) Dehydration of sand washing mud: The conditioned sand washing mud is dehydrated by a plate and frame filter press to obtain a filter cake with a moisture content of 26%; the filter cake is further air-dried, and the moisture content of the filter cake after air drying is 9%.

[0054] (3) Filter cake crushing: The air-dried filter cake is crushed by a planetary mixer to obtain washed sand mud particles with a particle size of less than 2.0 mm.

[0055] (4) Raw material mixing: Add 16 wt% of solidified material to the crushed sand washing mud filter cake and stir for 5 minutes to obtain homogenized material.

[0056] (5) Extrusion vibration molding: The evenly mixed materials are placed into the molding machine for extrusion vibration molding to form a solidified body.

[0057] (6) Curing: Curing the solidified body at a curing temperature of 80°C and a curing humidity of 60% for 12 hours, and then transferring it to a curing temperature of 20°C and a curing humidity of 95% for further curing for 28 days.

[0058] Comparative Example 1:

[0059] This comparative example provides an integrated treatment method for dehydration, crushing and solidification of sand washing mud. The specific steps are the same as those in Example 1, except that in step (1), the skeleton structure fly ash is not added.

[0060] Comparative Example 2:

[0061] This comparative example provides an integrated treatment method for dehydration, crushing and solidification of sand washing mud. The specific steps are the same as those in Example 2, except that in step (1), the skeleton structure fly ash is not added.

[0062] Comparative Example 3:

[0063] This comparative example provides an integrated treatment method for dehydration, crushing and solidification of sand washing mud. The specific steps are the same as those in Example 3, except that in step (1), the skeleton structure coal gasification slag is not added.

[0064] Comparative Example 4:

[0065] This comparative example provides an integrated treatment method for dehydration, crushing and solidification of sand washing mud. The specific steps are the same as those in Example 2, except that in step (1), no chemical flocculant is added.

[0066] The moisture content of the filter cakes obtained from Examples 1-3 and Comparative Examples 1-4 was tested, and the results are shown in Table 1. The crushing performance of the filter cake was characterized by the 0.30 mm sieve pass rate, and the curing effect of the washed sand mud-based solidified body was characterized by the 28-day compressive strength.

[0067] Table 1 Moisture content, sieve pass rate and compressive strength data

[0068] ;

[0069] From the above data, it can be concluded that the water content of the sand washing mud treated by the method disclosed in the present invention is significantly reduced from 90~96% to 25~28%. Compared with the data in the comparative example without adding the physical skeleton structure and the chemical flocculant, the water content of the filter cake after the filter press dehydration is effectively reduced; the 0.3mm sieve hole pass rate of the filter cake broken into small particles is greater than 70%, showing a good crushing effect; the 28-day compressive strength of the sand washing mud-based solidified body is greater than 10MPa.

[0070] Therefore, the disclosed integrated dehydration, crushing, and solidification method for sand washing mud, combined with low-carbon material technology, has transformed sand washing mud processing from "high pollution and low efficiency" to "resource utilization and high performance." This method combines the triple benefits of process innovation, environmental compliance, and economic feasibility, providing a highly efficient solution for the resource utilization of construction waste. Furthermore, the method is suitable for diverse building material applications, including roadbed materials, unfired bricks, and artificial aggregates.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A sand washing mud dehydration, crushing, and solidification integrated treatment method, characterized in that: The following steps are involved: S1. Mixing and stirring a conditioning agent and sand washing mud to obtain conditioned sand washing mud; the conditioning agent includes a chemical flocculant and a physical skeleton structure, the chemical flocculant is a mixed solution of polyacrylamide and polyaluminum chloride, and the physical skeleton structure is either fly ash or coal gasification slag; the addition amount of polyacrylamide is 0.2 g / L, and the addition amount of polyaluminum chloride is 1.0 g / L; S2, conveying the conditioned washed sand mud obtained in S1 to a plate and frame filter press for mechanical dehydration, followed by air drying to obtain a deeply dehydrated washed sand mud filter cake; S3, crushing the sand washing mud filter cake obtained in S2 through a mixer to obtain small sand washing mud particles; S4, mixing the solidified material and the small particles of washed sand mud obtained in S3 uniformly in a blender to obtain a mixture; the solidified material is sodium water glass, which has a modulus of 1.5 and a solid content of 42 wt % after adjustment with sodium hydroxide, and the amount of sodium water glass added is 12-16 wt %; S5, placing the mixture obtained in S4 into a mold for extrusion and vibration molding to obtain a solidified body; S6. The solidified body obtained in S5 is transported to a curing room for curing to obtain a washed sand mud-based solidified body.

2. The integrated treatment method for dehydration, crushing and solidification of sand washing mud according to claim 1, characterized in that: In step S1, the water content of the sand washing mud is 90-96%, and the particle size of the sand washing mud is ≤0.15 mm.

3. The integrated treatment method for dehydration, crushing and solidification of sand washing mud according to claim 1, characterized in that: In step S1, the amount of the physical skeleton structure added is 20-40% of the dry mass of the sand washing mud. The specific steps of step S1 include: S1-1. Add chemical flocculant into sand washing mud and stir for 5-10 minutes; S1-2. Add the physical framework construct to the mixture in S1-1 and stir for 5-10 minutes.

4. The integrated dehydration, crushing and solidification treatment method for sand washing mud according to claim 3 is characterized in that: The polyacrylamide is an anionic polyacrylamide with a molecular weight of 12 million, the mass concentration of the polyacrylamide solution is 0.2 wt %, the mass concentration of polyaluminium chloride is 1.0 wt %, and the amount of the physical skeleton structure added is 30 wt % of the dry mass of the sand washing mud.

5. The integrated dehydration, crushing and solidification treatment method for sand washing mud according to claim 1 is characterized in that: In step S2, the moisture content of the mechanically dehydrated sand washing mud filter cake is 25-30%, and the moisture content of the deeply dehydrated filter cake is 8-12%.

6. The integrated treatment method for dehydration, crushing and solidification of sand washing mud according to claim 1, characterized in that: In step S3, the small particles of washed sand mud are particles with a particle size of less than 2.0 mm.

7. The integrated dehydration, crushing and solidification treatment method for sand washing mud according to claim 1 is characterized in that: In step S5 , the vibration time of the extrusion vibration molding is 10 s, the molding pressure is 10 MPa, and the holding time is 20 s.

8. The integrated dehydration, crushing and solidification treatment method for sand washing mud according to claim 1 is characterized in that: In step S6, the curing conditions are to cure the solidified body at a curing temperature of 80° C. and a curing humidity of 60% for 12 to 24 hours, and then transfer the cured body to a curing temperature of 20° C. and a curing humidity of 95% for further curing until the specified age.