Resource-based treatment method for dyeing and printing sludge in building materials using non-fired low-temperature process

Abstract

This invention relates to a method for the resource-based treatment of dyeing and printing sludge in building materials based on a non-calcining, low-temperature process, belonging to the field of sludge resource-based treatment technology. To address the problem that existing dyeing and printing sludge treatment methods cannot simultaneously achieve safety, environmental protection, and resource recovery, this invention provides a method for the resource-based treatment of dyeing and printing sludge in building materials based on a non-calcining, low-temperature process. The method involves pre-dehydration, crushing and screening, harmless treatment, and drying to obtain resource-recovered dyeing and printing sludge materials. This invention utilizes a Fenton reaction system and alkalization treatment to harmlessly treat organic pollutants and heavy metal ions, respectively, without causing secondary pollution, taking advantage of the inherent characteristics of dyeing and printing sludge. It eliminates the need for high-temperature, high-pressure processes, enabling the resource-based treatment of dyeing and printing sludge in building materials to be completed at room temperature. The resource-recovered dyeing and printing sludge powder obtained by this invention can be directly used as an admixture in the preparation of cement-based building materials, reducing both the production cost and the carbon footprint of these products.

Description

Technical Field

[0001] This invention belongs to the field of sludge resource utilization technology, and particularly relates to a method for resource utilization of dyeing and printing sludge in building materials based on a non-calcining low-temperature process. Background Technology

[0002] Textile dyeing sludge originates from the textile dyeing and printing industry and is characterized by high water content, complex composition, and a large amount of recalcitrant organic compounds from dyes. Due to these characteristics, textile dyeing sludge is difficult to utilize as a resource. Currently, the main focus of textile dyeing sludge disposal is on how to efficiently dewater it, reduce its volume, and facilitate storage, transfer, and transportation.

[0003] Currently, the main methods for disposing of dyeing and printing sludge are traditional landfill and incineration. Because dyeing and printing sludge contains a large amount of organic matter and even heavy metal ions, these two methods inevitably cause environmental pollution. Specifically, landfilling dyeing and printing sludge easily leads to soil and groundwater pollution, posing a significant safety hazard to the surrounding flora and fauna and a very high probability of secondary pollution. Incinerating dyeing and printing sludge, firstly, due to its high water content, consumes a large amount of energy during the incineration process and emits large amounts of carbon dioxide and other waste gases, causing air pollution; secondly, because dyeing and printing sludge contains a large amount of organic matter, such as polycyclic aromatic compounds, toxic and harmful substances such as dioxins, nitrogen oxides, sulfur dioxide, and fly ash are produced during incineration, seriously impacting the environment and human health.

[0004] Based on existing literature, no effective approach for the resource utilization of dyeing and printing sludge has yet been established. In fact, dried dyeing and printing sludge can be classified as industrial solid waste. Analysis of its composition reveals that it contains relatively abundant alumina, silica, and calcium oxide. With proper treatment, it can be used as an admixture in building materials, representing an effective way to realize the resource utilization of dyeing and printing sludge. However, the prerequisite for implementing this method is the ability to safely and effectively pre-treat the dyeing and printing sludge. This process must remove organic matter while ensuring no secondary pollution is caused, and simultaneously achieve low-carbon and green disposal.

[0005] Therefore, how to achieve the resource utilization of dyeing and printing sludge while ensuring safety and environmental protection remains an urgent problem to be solved in this field. Summary of the Invention

[0006] To address the problem that existing dyeing and printing sludge treatment methods cannot simultaneously achieve safety, environmental protection, and resource recovery, this invention provides a method for the resource recovery of dyeing and printing sludge into building materials based on a non-fired, low-temperature process.

[0007] The technical solution of this invention:

[0008] A method for the resource-based treatment of dyeing and printing sludge in building materials using a non-fired, low-temperature process includes the following steps:

[0009] Step 1: Pre-dehydration treatment:

[0010] The moisture content of dyeing and printing sludge in a water-saturated state is reduced to below the saturated moisture content by using traditional physical industrial sludge dewatering methods to obtain pre-dewatered dyeing and printing sludge.

[0011] Step 2: Crushing and Screening Process:

[0012] The pre-dehydrated dyeing sludge obtained in step one is mechanically crushed to obtain fragments; the fragments are further refined and crushed while being dried to obtain smaller particles; the obtained particles are screened, and the particles that do not pass the screen are returned to continue crushing; the particles that pass the screen are the refined dyeing sludge.

[0013] Step 3: Harmless treatment:

[0014] The residual organic matter in the refined dyeing sludge obtained in step two is decomposed by Fenton reaction to obtain deorganized dyeing sludge; the obtained deorganized dyeing sludge is then alkalized to obtain alkalized sludge.

[0015] Step 4: Drying treatment:

[0016] The alkalized sludge obtained in step three is subjected to solid-liquid separation and drying to obtain dyeing and printing sludge powder.

[0017] Furthermore, the traditional physical industrial sludge dewatering method described in step one includes plate filter press or centrifugal dewatering; the moisture content of the pre-dewatered dyeing sludge is 55-75%.

[0018] Furthermore, the mechanical crushing described in step two involves conveying the pre-dehydrated dyeing sludge to an auger conveyor for crushing, resulting in fragments with a particle size of 0.5–2.0 cm.

[0019] Furthermore, the refining and crushing described in step two involves transferring the obtained fragments to a steam drying device equipped with auger blades, introducing hot steam into the device to dry the fragments, and simultaneously rotating the auger to further crush the fragments.

[0020] Furthermore, the screening described in step two is carried out using a graded vibrating screen. Two grades of grading screens with screen aperture sizes of 19mm and 0.3mm are selected for fineness control. Particles that cannot pass through the 19mm screen are returned for further mechanical crushing, while particles that pass through the 19mm screen but cannot pass through the 0.3mm screen are returned for further fine crushing.

[0021] Furthermore, in step three, the Fenton reaction involves placing the refined dyeing sludge obtained in step two and water into a Fenton reaction apparatus, stirring to obtain a dyeing sludge slurry, adding an inorganic acid solution to adjust the pH of the dyeing sludge slurry to 2.5–3.5, adding ferrous sulfate and hydrogen peroxide, and continuously stirring to ensure the Fenton reaction proceeds fully.

[0022] Furthermore, the mass ratio of the refined dyeing sludge, water, ferrous sulfate, and hydrogen peroxide is 7–12:7–10:0.20–0.35:0.80–1.20; the inorganic acid solution is sulfuric acid; and the continuous stirring time is 0.5–1.5 hours.

[0023] Furthermore, the alkalization treatment described in step three involves adding an alkaline compound to the deorganized dyeing slurry and stirring thoroughly for 15–45 minutes.

[0024] Furthermore, the alkaline compound is quicklime, industrial caustic soda, hydrated lime, or soda ash, and the amount of alkaline compound added is calculated based on a mass ratio of refined dyeing sludge to alkaline compound of 10:1.0 to 2.0.

[0025] Furthermore, the solid-liquid separation described in step four is carried out using a centrifugal dehydration device.

[0026] The beneficial effects of this invention are:

[0027] The non-combustion, low-temperature process provided by this invention is a green treatment method developed specifically for the characteristics of dyeing and printing sludge, which has high water content and contains organic pollutants and heavy metal ions. The Fenton reaction system and alkalization treatment target the organic pollutants and heavy metal ions that may be introduced into the dyes, respectively, ensuring that the dyeing and printing sludge will not cause secondary pollution during resource utilization. This invention's dyeing and printing sludge resource utilization process does not require high-temperature, high-pressure, or high-energy-consumption processes; the resource utilization disposal of dyeing and printing sludge can be completed under ambient temperature conditions.

[0028] Based on the present invention, the resource-based treatment of dyeing and printing sludge obtained can be directly used as an admixture in the preparation of cement-based building materials without further processing. Under the premise of meeting safety and usage requirements, it can partially replace 20-50% of ordinary Portland cement, directly reducing cement usage. This can reduce the production cost of building materials and the carbon footprint of building materials, thus contributing to the greening process of the civil engineering materials industry.

[0029] This invention provides an effective way to utilize dyeing and printing sludge and similar sludge. Based on the disposal method of this invention, a broad scope for the resource utilization of dyeing and printing sludge can be provided.

[0030] This invention provides a treatment method for the main hazards of dyeing and printing sludge, and designs a disposal process suitable for continuous production based on actual industrial production. At the same time, this invention fully considers the material characteristics of mineral admixtures in cement-based building materials and incorporates a process for controlling the particle size of dyeing and printing sludge through screening. Attached Figure Description

[0031] Figure 1 This is a photograph of the dyeing sludge powder obtained by the method for resource utilization of dyeing sludge in building materials according to the present invention.

[0032] Figure 2 A photograph of a sludge brick prepared using the dyeing and printing sludge powder prepared in Example 1 as raw material;

[0033] Figure 3 A photograph of a prototype of a building material prepared using the dyeing and printing sludge powder obtained in this invention as raw material in a small-scale production trial.

[0034] Figure 4 The image shows a physical photograph of a pilot-scale production specimen of building materials prepared using the dyeing and printing sludge powder obtained in this invention as raw material. Detailed Implementation

[0035] The technical solution of the present invention will be further described below with reference to embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention. In the following embodiments, the process equipment or apparatus not specifically specified are all conventional equipment or apparatus in the art. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commercially available; unless otherwise specified, the technical means used in the embodiments of the present invention are all conventional means well known to those skilled in the art.

[0036] Example 1

[0037] This embodiment provides a method for the resource-based treatment of dyeing and printing sludge into building materials based on a non-calcining, low-temperature process, which specifically includes the following steps:

[0038] Step 1: Pre-dehydration treatment:

[0039] The dyeing sludge, which is in a water-saturated state, is added to a plate filter press for physical dewatering. During the filtration process, a 25-mesh sponge rubber outer filter cloth and a 100-mesh textile filter cloth are selected for the dewatering of the dyeing sludge. After the physical dewatering process, the moisture content of the dyeing sludge is reduced to 70%, and a dyeing sludge cake, i.e., pre-dewatered dyeing sludge, is obtained.

[0040] Step 2: Crushing and Screening Process:

[0041] The dyeing sludge cake obtained in step one is conveyed to the auger conveyor for crushing, and the dyeing sludge cake is crushed into dyeing sludge fragments with a particle size of 0.5-2.0 cm. The obtained fragments are transferred to a steam drying device equipped with auger blades via a conveyor belt. Hot steam is introduced into the device to dry the dyeing sludge fragments, while the auger rotates slowly to further refine and crush the dyeing sludge fragments to obtain smaller particles.

[0042] The resulting particles are screened by a grading vibrating screen. Two grading screens with screen sizes of 19mm and 0.3mm are selected to control the particle fineness. Large particles that cannot pass through the 19mm screen are returned to the auger conveyor for further mechanical crushing. Particles that pass through the 19mm screen but cannot pass through the 0.3mm screen are returned to the steam dryer equipped with auger blades for further fine crushing. Sludge particles that pass through the 0.3mm screen are collected and used as refined dyeing sludge.

[0043] Step 3: Harmless treatment:

[0044] The residual organic matter in the refined dyeing and printing sludge obtained in step two is decomposed using the Fenton reaction. Specifically, 10 parts by weight of the refined dyeing and printing sludge are transferred to the Fenton reactor, and 10 parts by weight of water and 0.25 parts by weight of ferrous sulfate are added. The mechanical agitator of the equipment is turned on to form a dyeing and printing sludge slurry with a solid-liquid ratio of 1:1. The pH of the dyeing and printing sludge slurry is adjusted to 3.5 using sulfuric acid, and then 1 part by weight of hydrogen peroxide is added. The mixture is stirred continuously for 1 hour to ensure that the chemical treatment is fully carried out, resulting in a deorganized dyeing and printing sludge slurry.

[0045] The obtained deorganized dyeing and printing sludge was pumped to an alkalization treatment tank, and 1.2 parts by weight of quicklime were added and stirred thoroughly for 25 minutes to form a stable alkaline alkalized sludge.

[0046] Step 4: Alkaliization and Drying Treatment

[0047] The alkalized sludge obtained in step three is pumped to a centrifugal dewatering device for solid-liquid separation to obtain alkalized dyeing and printing sludge with a certain moisture content. Then, the water-containing alkalized dyeing and printing sludge is transferred to a blower drying device for drying to obtain dried dyeing and printing sludge powder, which is the material for the resource utilization of dyeing and printing sludge in building materials.

[0048] Example 2

[0049] This embodiment provides a method for the resource-based treatment of dyeing and printing sludge into building materials based on a non-calcining, low-temperature process, which specifically includes the following steps:

[0050] Step 1: Pre-dehydration treatment:

[0051] The dyeing sludge, which is in a water-saturated state, is added to a plate filter press for physical dewatering. During the filtration process, a 25-mesh sponge rubber outer filter cloth and a 100-mesh textile filter cloth are selected for the pressure filtration and dewatering of the dyeing sludge. After the physical dewatering process, the moisture content of the dyeing sludge is reduced to 60%, and a dyeing sludge cake is obtained, which is the pre-dewatered dyeing sludge.

[0052] Step 2: Crushing and Screening Process:

[0053] The dyeing sludge cake obtained in step one is conveyed to the auger conveyor for crushing, and the dyeing sludge cake is crushed into dyeing sludge fragments with a particle size of 0.5-2.0 cm. The obtained fragments are transferred to a steam drying device equipped with auger blades via a conveyor belt. Hot steam is introduced into the device to dry the dyeing sludge fragments, while the auger rotates slowly to further refine and crush the dyeing sludge fragments to obtain smaller particles.

[0054] The resulting particles are screened by a grading vibrating screen. Two grading screens with screen sizes of 19mm and 0.3mm are selected to control the particle fineness. Large particles that cannot pass through the 19mm screen are returned to the auger conveyor for further mechanical crushing. Particles that pass through the 19mm screen but cannot pass through the 0.3mm screen are returned to the steam dryer equipped with auger blades for further fine crushing. Sludge particles that pass through the 0.3mm screen are collected and used as refined dyeing sludge.

[0055] Step 3: Harmless treatment:

[0056] The residual organic matter in the refined dyeing and printing sludge obtained in step two was decomposed using the Fenton reaction. Specifically, 7 parts by weight of the refined dyeing and printing sludge were transferred to the Fenton reactor, and 10 parts by weight of water and 0.20 parts by weight of ferrous sulfate were added. The mechanical agitator of the equipment was turned on to form a dyeing and printing sludge slurry with a solid-liquid ratio of 0.7:1. The pH of the dyeing and printing sludge slurry was adjusted to 2.8 using sulfuric acid, and then 0.9 parts by weight of hydrogen peroxide were added. The mixture was stirred continuously for 1.5 hours to ensure that the chemical treatment was fully carried out, resulting in a deorganized dyeing and printing sludge slurry.

[0057] The obtained deorganized dyeing and printing sludge was pumped to an alkalization treatment tank, and 1.4 parts by weight of soda ash was added and stirred thoroughly for 45 minutes to form a stable alkaline alkalized sludge.

[0058] Step 4: Alkaliization and Drying Treatment

[0059] The alkalized sludge obtained in step three is pumped to a centrifugal dewatering device for solid-liquid separation to obtain alkalized dyeing and printing sludge with a certain moisture content. Then, the water-containing alkalized dyeing and printing sludge is transferred to a blower drying device for drying to obtain dried dyeing and printing sludge powder, which is the material for the resource utilization of dyeing and printing sludge in building materials.

[0060] Example 3

[0061] This embodiment provides a method for the resource-based treatment of dyeing and printing sludge into building materials based on a non-calcining, low-temperature process, which specifically includes the following steps:

[0062] Step 1: Pre-dehydration treatment:

[0063] The dyeing sludge, which is in a water-saturated state, is added to a plate filter press for physical dewatering. During the filtration process, a 25-mesh sponge rubber outer layer filter cloth and a 100-mesh textile filter cloth are selected for the dewatering of the dyeing sludge. After the physical dewatering process, the moisture content of the dyeing sludge is reduced to 75%, and a dyeing sludge cake, i.e., pre-dewatered dyeing sludge, is obtained.

[0064] Step 2: Crushing and Screening Process:

[0065] The dyeing sludge cake obtained in step one is conveyed to the auger conveyor for crushing, and the dyeing sludge cake is crushed into dyeing sludge fragments with a particle size of 0.5-2.0 cm. The obtained fragments are transferred to a steam drying device equipped with auger blades via a conveyor belt. Hot steam is introduced into the device to dry the dyeing sludge fragments, while the auger rotates slowly to further refine and crush the dyeing sludge fragments to obtain smaller particles.

[0066] The resulting particles are screened by a grading vibrating screen. Two grading screens with screen sizes of 19mm and 0.3mm are selected to control the particle fineness. Large particles that cannot pass through the 19mm screen are returned to the auger conveyor for further mechanical crushing. Particles that pass through the 19mm screen but cannot pass through the 0.3mm screen are returned to the steam dryer equipped with auger blades for further fine crushing. Sludge particles that pass through the 0.3mm screen are collected and used as refined dyeing sludge.

[0067] Step 3: Harmless treatment:

[0068] The residual organic matter in the refined dyeing and printing sludge obtained in step two was decomposed using the Fenton reaction. Specifically, 12 parts by weight of the refined dyeing and printing sludge were transferred to the Fenton reactor, and 8 parts by weight of water and 0.27 parts by weight of ferrous sulfate were added. The mechanical agitator of the equipment was turned on to form a dyeing and printing sludge slurry with a solid-liquid ratio of 1.5:1. The pH of the dyeing and printing sludge slurry was adjusted to 3.0 using sulfuric acid, and then 1.1 parts by weight of hydrogen peroxide were added. The mixture was stirred continuously for 1 hour to ensure that the chemical treatment was fully carried out, resulting in a deorganized dyeing and printing sludge slurry.

[0069] The obtained deorganized dyeing and printing sludge was pumped to an alkalization treatment tank, and 1.2 parts by weight of industrial caustic soda were added and stirred thoroughly for 15 minutes to form a stable alkaline alkalized sludge.

[0070] Step 4: Alkaliization and Drying Treatment

[0071] The alkalized sludge obtained in step three is pumped to a centrifugal dewatering device for solid-liquid separation to obtain alkalized dyeing and printing sludge with a certain moisture content. Then, the water-containing alkalized dyeing and printing sludge is transferred to a blower drying device for drying to obtain dried dyeing and printing sludge powder, which is the material for the resource utilization of dyeing and printing sludge in building materials.

[0072] Example 4

[0073] This embodiment provides a method for the resource-based treatment of dyeing and printing sludge into building materials based on a non-calcining, low-temperature process, which specifically includes the following steps:

[0074] Step 1: Pre-dehydration treatment:

[0075] The dyeing and printing sludge, which is in a water-saturated state, is added to a plate filter press for physical dewatering. During the filtration process, a 25-mesh sponge rubber outer layer filter cloth and a 100-mesh textile filter cloth are selected for the pressure filtration and dewatering of the dyeing and printing sludge. After the physical dewatering process, the moisture content of the dyeing and printing sludge is reduced to 65%, and dyeing and printing sludge cake is obtained, which is pre-dewatered dyeing and printing sludge.

[0076] Step 2: Crushing and Screening Process:

[0077] The dyeing sludge cake obtained in step one is conveyed to the auger conveyor for crushing, and the dyeing sludge cake is crushed into dyeing sludge fragments with a particle size of 0.5-2.0 cm. The obtained fragments are transferred to a steam drying device equipped with auger blades via a conveyor belt. Hot steam is introduced into the device to dry the dyeing sludge fragments, while the auger rotates slowly to further refine and crush the dyeing sludge fragments to obtain smaller particles.

[0078] The resulting particles are screened by a grading vibrating screen. Two grading screens with screen sizes of 19mm and 0.3mm are selected to control the particle fineness. Large particles that cannot pass through the 19mm screen are returned to the auger conveyor for further mechanical crushing. Particles that pass through the 19mm screen but cannot pass through the 0.3mm screen are returned to the steam dryer equipped with auger blades for further fine crushing. Sludge particles that pass through the 0.3mm screen are collected and used as refined dyeing sludge.

[0079] Step 3: Harmless treatment:

[0080] The residual organic matter in the refined dyeing and printing sludge obtained in step two was decomposed using the Fenton reaction. Specifically, 8 parts by weight of the refined dyeing and printing sludge were transferred to the Fenton reactor, and 10 parts by weight of water and 0.30 parts by weight of ferrous sulfate were added. The mechanical agitator of the equipment was turned on to form a dyeing and printing sludge slurry with a solid-liquid ratio of 0.8:1. The pH of the dyeing and printing sludge slurry was adjusted to 3.2 using sulfuric acid, and then 1.2 parts by weight of hydrogen peroxide were added. The mixture was stirred continuously for 1.5 hours to ensure that the chemical treatment was fully carried out, resulting in a deorganized dyeing and printing sludge slurry.

[0081] The obtained deorganized dyeing and printing sludge was pumped to an alkalization treatment tank, and 1.5 parts by weight of quicklime were added and stirred thoroughly for 30 minutes to form a stable alkaline alkalized sludge.

[0082] Step 4: Alkaliization and Drying Treatment

[0083] The alkalized sludge obtained in step three is pumped to a centrifugal dewatering device for solid-liquid separation to obtain alkalized dyeing and printing sludge with a certain moisture content. Then, the water-containing alkalized dyeing and printing sludge is transferred to a blower drying device for drying to obtain dried dyeing and printing sludge powder, which is the material for the resource utilization of dyeing and printing sludge in building materials.

[0084] Comparative Example 1

[0085] This comparative example provides a method for preparing sludge without prior harmless treatment, specifically including the following steps:

[0086] Step 1: Pre-dehydration treatment:

[0087] The dyeing sludge, which is in a water-saturated state, is added to a plate filter press for physical dewatering. During the filtration process, a 25-mesh sponge rubber outer filter cloth and a 100-mesh textile filter cloth are selected for the dewatering of the dyeing sludge. After the physical dewatering process, the moisture content of the dyeing sludge is reduced to 70%, and a dyeing sludge cake, i.e., pre-dewatered dyeing sludge, is obtained.

[0088] Step 2: Crushing and Screening Process:

[0089] The dyeing sludge cake obtained in step one is conveyed to the auger conveyor for crushing, and the dyeing sludge cake is crushed into dyeing sludge fragments with a particle size of 0.5-2.0 cm. The obtained fragments are transferred to a steam drying device equipped with auger blades via a conveyor belt. Hot steam is introduced into the device to dry the dyeing sludge fragments, while the auger rotates slowly to further refine and crush the dyeing sludge fragments to obtain smaller particles.

[0090] The resulting particles are screened by a grading vibrating screen. Two grading screens with screen sizes of 19mm and 0.3mm are selected to control the particle fineness. Large particles that cannot pass through the 19mm screen are returned to the auger conveyor for further mechanical crushing. Particles that pass through the 19mm screen but cannot pass through the 0.3mm screen are returned to the steam dryer equipped with auger blades for further fine crushing. Sludge particles that pass through the 0.3mm screen are collected and used as refined dyeing sludge.

[0091] Using the dyeing sludge powder obtained in Examples 1-4 and the refined dyeing sludge prepared in Comparative Example 1 as raw materials, the following preparations were made respectively: Figure 2 The sludge brick shown has a volume of 40mm × 40mm × 40mm. The laboratory mix design of the sludge brick is shown in Table 1.

[0092] Table 1

[0093]

[0094] The preparation method of sludge bricks is as follows:

[0095] In preparing sludge bricks, cement was first dry-mixed with the dyeing sludge powder obtained in Examples 1-4 or the refined dyeing sludge prepared in Comparative Example 1 for 1-2 minutes. Then, river sand was added and dry-mixed for another 1 minute to form a uniform dry mixture. The mixer was kept running continuously while water was slowly poured into the mixer and rapidly mixed for 2-4 minutes to form a uniform slurry. Mixing was stopped, and the slurry was poured into a mold and vibrated to form the bricks. The molded specimens were covered with a waterproof film and left to stand at room temperature (20±2℃) for 24 hours before demolding. After demolding, the specimens were cured under standard curing conditions (20±2℃, 95% RH) for 27 days, and then mechanical property tests were performed. The compressive strength of the obtained sludge bricks was tested, and the results are shown in Table 2.

[0096] Table 2

[0097] Testing items Load (kN) Strength (MPa) Example 1 36.08 22.6 Example 2 36.14 22.6 Example 3 38.71 24.2 Example 4 36.98 23.1 Comparative Example 1 11.15 7.0

[0098] The results are shown in Table 2. The sludge bricks prepared from the harmlessly treated dyeing and printing sludge powder have higher compressive strength. This is because during the harmless treatment process, harmful substances such as organic matter and heavy metals in the dyeing and printing sludge are removed, which changes the chemical composition of the sludge and increases the proportion of inorganic matter in the sludge. As a result, a more stable mineral structure is formed during the preparation of sludge bricks, thereby improving the compressive strength of the bricks.

[0099] The dyeing and printing sludge resource-based building material obtained by this invention can replace 30% of ordinary Portland cement to prepare building materials such as cement mortar, cement concrete, and cement-based imitation stone bricks. Figure 3 and Figure 4The images shown are photographs of small-scale and pilot-scale production specimens of sludge bricks prepared using the dyeing and printing sludge powder obtained in this invention as raw material. This invention, based on a non-fired, low-temperature process for the resource-based treatment of dyeing and printing sludge in building materials, yields dyeing and printing sludge materials that, while meeting safety and usability requirements, can partially replace 20-50% of ordinary Portland cement, directly reducing cement usage. This not only lowers the production cost of building materials but also reduces their carbon footprint, contributing to the greening process of the civil engineering materials industry.

Claims

1. A method for resource-based treatment of dyeing and printing sludge in building materials based on a non-calcining, low-temperature process, characterized in that, Includes the following steps: Step 1: Pre-dehydration treatment: The moisture content of dyeing and printing sludge in a water-saturated state is reduced to below the saturated moisture content by using traditional physical industrial sludge dewatering methods to obtain pre-dewatered dyeing and printing sludge. Step 2: Crushing and Screening Process: The pre-dehydrated dyeing sludge obtained in step one is mechanically crushed to obtain fragments; the fragments are further refined and crushed while being dried to obtain smaller particles; the obtained particles are screened, and the particles that do not pass the screen are returned to continue crushing; the particles that pass the screen are the refined dyeing sludge. Step 3: Harmless treatment: The residual organic matter in the refined dyeing sludge obtained in step two is decomposed by Fenton reaction to obtain deorganized dyeing sludge; the obtained deorganized dyeing sludge is then alkalized to obtain alkalized sludge. Step 4: Drying treatment: The alkalized sludge obtained in step three is subjected to solid-liquid separation and drying to obtain printing and dyeing sludge powder; The dyeing and printing sludge powder can be directly used as an admixture in the preparation of cement-based building materials. The traditional physical industrial sludge dewatering method described in step one includes plate filter press or centrifugal dewatering; the moisture content of the pre-dewatered dyeing sludge is 55-75%. The screening described in step two is carried out using a grading vibrating screen. Two grading screens with screen aperture sizes of 19mm and 0.3mm are selected for fineness control. Particles that cannot pass through the 19mm screen are returned for further mechanical crushing, while particles that pass through the 19mm screen but cannot pass through the 0.3mm screen are returned for further fine crushing. The Fenton reaction described in step three involves placing the refined dyeing sludge obtained in step two and water into a Fenton reaction apparatus, stirring to obtain a dyeing sludge slurry, adding an inorganic acid solution to adjust the pH of the dyeing sludge slurry to 2.5-3.5, adding ferrous sulfate and hydrogen peroxide, and continuously stirring to ensure that the Fenton reaction proceeds fully. The mass ratio of the refined dyeing sludge, water, ferrous sulfate, and hydrogen peroxide is 7~12:7~10:0.20~0.35:0.80~1.20; the inorganic acid solution is sulfuric acid; and the continuous stirring time is 0.5~1.5 hours. The alkalization treatment described in step three involves adding an alkaline compound to the deorganized dyeing slurry and stirring thoroughly for 15 to 45 minutes. The alkaline compound is quicklime, industrial caustic soda, hydrated lime, or soda ash. The amount of alkaline compound added is calculated based on a mass ratio of 10:1.0 to 2.0 between the refined dyeing slurry and the alkaline compound.

2. The method for resource-based treatment of dyeing and printing sludge as building material based on non-fired low-temperature process according to claim 1, characterized in that, The mechanical crushing described in step two involves conveying the pre-dehydrated dyeing sludge to an auger conveyor for crushing, resulting in fragments with a particle size of 0.5~2.0cm.

3. The method for resource-based treatment of dyeing and printing sludge as building materials based on a non-fired low-temperature process according to claim 2, characterized in that, Step two, the refining and crushing process, involves transferring the resulting fragments to a steam drying device equipped with auger blades, introducing hot steam into the device to dry the fragments, and simultaneously rotating the auger to further crush the fragments.

4. The method for resource-based treatment of dyeing and printing sludge as building material based on non-fired low-temperature process according to claim 1, characterized in that, The solid-liquid separation described in step four is carried out using a centrifugal dehydration device.

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