Dyeing sludge dewatering method, high-aluminum calorific value soil and cement

Abstract

This invention discloses a method for dewatering dyeing and printing sludge, high-alumina calorific value clay, and cement, relating to the field of sludge treatment technology. The method for dewatering dyeing and printing sludge includes the following steps: adding flocculant and aluminum ash to the sludge thickening stage, stirring evenly to allow for sufficient flocculation and sedimentation, followed by plate and frame filtration. Through plate and frame filtration, a composite dewatered cement cake of dyeing and printing sludge and high-alumina material with a moisture content of 40-53% can be obtained. By adding flocculant and aluminum ash in the sludge thickening stage, the heat generated by the hydrolysis of aluminum ash promotes better flocculant dispersal. Simultaneously, aluminum ash reacts with water to produce aluminum hydroxide, improving the sludge flocculation effect. Furthermore, during plate and frame filtration, the gas and heat generated during the hydrolysis of aluminum nitride and aluminum carbide in the aluminum ash form moisture channels in the cement cake during filtration, facilitating water extraction and reducing the moisture content of the dewatered cement cake to as low as 40%. This dewatered cement cake contains a high aluminum content, which can be used to produce high-alumina calorific value clay for cement production.

Description

Technical Field

[0001] This invention relates to the field of sludge treatment technology, and in particular to a method for dewatering dyeing and printing sludge, high-alumina calorific value soil, and cement. Background Technology

[0002] Textile dyeing sludge is a solid waste generated during wastewater treatment in the textile dyeing industry, containing substances such as dyes, fabric hair, and surfactants. Currently, my country's textile dyeing industry generates approximately 2.1 billion tons of wastewater annually, which, after treatment, produces about 21 million tons of dyeing sludge. However, due to the high water content of dyeing sludge, it is difficult to recycle and reuse. Furthermore, traditional sludge treatment and disposal methods mainly include incineration, landfill, anaerobic digestion, and land application, but these methods are highly likely to cause secondary pollution to the environment.

[0003] Existing dewatering methods for dyeing and printing sludge typically employ flocculation, sedimentation, and pressure filtration. This method can reduce the sludge's moisture content to 60%, but it cannot achieve deep dewatering. Existing technology also discloses a method for improving the dewatering effect of municipal sludge using aluminum ash. This method involves treating the aluminum ash with a mixture of hexadecylammonium bromide and octadecyldimethylbenzylammonium chloride, followed by washing, filtration, and drying to obtain modified aluminum ash. The modified aluminum ash is then added to the municipal sludge, where stirring and sedimentation cause the solid particles and water in the sludge to separate. The settled solid-liquid material is then filtered under pressure to obtain a sludge cake with a low moisture content. Compared to the sludge obtained by currently used dewatering processes, this process significantly reduces the sludge's moisture content, down to below 50%. However, this method requires modification of the aluminum ash. During the modification process, the solid-liquid mixture needs to be washed and filtered multiple times, and then dried at a high temperature of 90–110°C, making the process cumbersome and energy-intensive.

[0004] It is evident that existing technologies still need improvement and enhancement. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for dewatering dyeing and printing sludge, high-alumina calorific value soil and cement, in order to solve the defects of existing dewatering methods that are difficult to deeply dewater dyeing and printing sludge.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for dewatering dyeing and printing sludge, wherein the method includes the following steps: adding flocculant and aluminum ash to the sludge thickening stage of dyeing and printing sludge, stirring evenly to allow it to fully flocculate and settle, and then performing plate and frame filter press to obtain dewatered sludge cake with a moisture content of 40-53%.

[0008] In the aforementioned method for dewatering dyeing and printing sludge, the flocculant includes one of polyaluminum sulfate, polyaluminum chloride, or polyacrylamide.

[0009] In the aforementioned method for dewatering dyeing and printing sludge, the amount of aluminum ash added is 18-30% of the dry weight of the dyeing and printing sludge.

[0010] In the aforementioned method for dewatering dyeing and printing sludge, a portion of the aluminum ash is added when the flocculant is added, and another portion of the aluminum ash is added after flocculation and sedimentation are complete.

[0011] A high-alumina calorific value soil, wherein the high-alumina calorific value soil is obtained by drying and crushing dewatered cement cake, wherein the dewatered cement cake is prepared by the dyeing and printing sludge dewatering method described above.

[0012] The high-alumina calorific value soil has an organic matter content of ≥25% in its dry matter and a calorific value of ≥1300 kcal; the alumina content in the mineral composition of the residue after burning at 800℃ is >23%.

[0013] A type of cement, wherein the raw materials for preparing the cement contain high-alumina calorific value clay as described in claim 5 or 6.

[0014] In the cement, the amount of high-alumina calorific value clay added is 5-15% by mass percentage in the cement raw materials.

[0015] The cement, by mass percentage, comprises: 83% limestone, 7% clay, 8% high-alumina calorific value clay, 1% iron ore powder, and 1% gypsum.

[0016] Beneficial effects:

[0017] This invention provides a method for dewatering dyeing and printing sludge. By adding flocculants and aluminum ash during the sludge thickening process, the heat generated by the hydrolysis of aluminum ash promotes better dissolution and chain expansion of the flocculant molecules, improving the flocculation effect. Simultaneously, the aluminum hydroxide produced by the hydrolysis of aluminum ash also has a flocculation effect, promoting the flocculation and sedimentation of the dyeing and printing sludge. Furthermore, during plate and frame filtration, the gas and heat generated during the hydrolysis of aluminum nitride and aluminum carbide in the aluminum ash form interconnected gas channels in the sludge cake during filtration. These gas channels serve as water filtration channels, facilitating the pressure filtration of water from the inside of the sludge cake, reducing the moisture content of the dewatered sludge cake. Additionally, the heat generated during the hydrolysis of aluminum nitride and aluminum carbide also promotes the formation of cracks inside the sludge cake, facilitating the pressure leaching of internal water and achieving deep dewatering. This can reduce the moisture content of the dewatered sludge cake after plate and frame filtration to as low as 40%, while also eliminating the hazardous waste properties of aluminum ash. The dewatered cement cake prepared by this method, after drying and pulverizing, can be made into a high-alumina calorific value material with an organic matter content of ≥25%, a calorific value of ≥800 kcal, and an alumina content of >20% in the mineral composition of the residue after burning at 800℃. When applied to cement clinker production, it can supplement aluminum, reduce the consumption of high-alumina bauxite minerals, and reduce the energy consumption of cement clinker firing. Attached Figure Description

[0018] Figure 1 This is a physical image of the dewatered cake prepared in Example 1 of the present invention.

[0019] Figure 2 This is a photograph of the dewatered cake prepared in Comparative Example 1.

[0020] Figure 3 This is a photograph of the high-alumina calorific value soil obtained in Example 1. Detailed Implementation

[0021] This invention provides a method for dewatering dyeing and printing sludge, high-alumina calorific value clay, and cement. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the following embodiments are provided to further illustrate the invention in detail. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0022] Because the moisture content of the dyeing sludge separated from dyeing wastewater is as high as 96-99%, current methods of dewatering through flocculation followed by mechanical pressure filtration can only remove about 60% of the water. Figure 2As shown, the moisture content remains high, leading to high energy consumption in subsequent drying processes and high recycling costs. To address this issue, this invention provides a method for dewatering dyeing and printing sludge. This method includes the following steps: adding flocculant and aluminum ash to the dyeing and printing sludge thickening stage, stirring evenly to allow for sufficient flocculation and sedimentation, followed by plate and frame filtration. Through plate and frame filtration, a dewatered sludge cake with a moisture content of 40-53% can be obtained. Figure 1 As shown.

[0023] In practice, the dyeing and printing sludge is usually placed in a thickening tank, which is equipped with an air extraction device to remove the odor generated by the dyeing and printing sludge and the gas generated during the hydrolysis of aluminum ash. Before adding flocculant and aluminum ash to the dyeing and printing sludge sludge, the proportion of the dry mass of the sludge in the dyeing and printing sludge can be measured first, and then the flocculant and aluminum ash can be added according to the dry mass of the sludge. During plate and frame filter press, an air extraction device is also provided to remove the waste gas.

[0024] In this embodiment, flocculants and aluminum ash are added during the slurry thickening process. The aluminum ash contains aluminum oxide, nitrides, and carbides, especially secondary aluminum ash, which contains a significant amount of aluminum nitride and aluminum carbide (see Table 1 for the composition of aluminum ash). These components generate gas upon contact with water, releasing a large amount of heat. Therefore, by adding aluminum ash during the flocculation and sedimentation process, on the one hand, the hydrolysis reaction of aluminum ash promotes better flocculant dispersibility and improves the flocculation effect; the aluminum hydroxide produced by aluminum ash hydrolysis also has a flocculating effect. On the other hand, during plate and frame filtration, the gas and heat generated during the hydrolysis of aluminum nitride and aluminum carbide form moisture channels in the slurry cake when these gases overflow, facilitating water extraction during plate and frame filtration and improving the dehydration rate. Furthermore, the heat generated during the hydrolysis of aluminum nitride and aluminum carbide causes cracks to form in the slurry cake from the inside out, facilitating the expulsion of internal moisture and achieving deep dehydration. This results in a dehydrated slurry cake with a moisture content as low as 45% after plate and frame filtration.

[0025] Table 1. Main aluminum components and content in aluminum ash

[0026] Serial Number Element content Determination methods 1 Aluminum 4.17％ Titration 2 <![CDATA[Al2O3]]> 39.44％ 3 AlN 17.24％ GB / T 609-2018 4 <![CDATA[Al4C3]]> 2.92％ GB / T 6730.61-2005

[0027] Furthermore, aluminum ash contains a significant amount of aluminum oxides, nitrides, and carbides, as well as salts (fluorides, chlorides, etc.). This causes aluminum ash to react with water, producing gases such as CH4, H2S, and NH3, and releasing heat dramatically. This is the main reason why aluminum ash is listed as hazardous waste (due to its high reactivity). This solution involves adding aluminum ash to the dyeing and printing sludge thickening tank. Because the water content in the sludge far exceeds the amount of aluminum ash, the heat generated by the reaction of aluminum ash with water will not significantly cause a sharp rise in water temperature. Simultaneously, the generated waste gas can be collected and treated together with the odor from the dyeing and printing sludge, greatly reducing the disposal cost of aluminum ash, eliminating its hazardous waste status, and making its use safer.

[0028] In a preferred embodiment, the flocculant includes one of polyaluminum sulfate, polyaluminum chloride, or polyacrylamide. These flocculants have a good flocculation effect on dyeing and printing sludge, enabling the sludge to quickly flocculate into clumps, facilitating water removal. More preferably, the flocculant is polyaluminum sulfate or polyaluminum chloride, which contains aluminum, increasing the aluminum content in the dewatered sludge cake and facilitating its application as high-alumina calorific value clay.

[0029] In a preferred embodiment, the amount of flocculant added is 1-5% of the dry weight of the dyeing and printing sludge, and the amount of aluminum ash added is 18-30% of the dry weight of the dyeing and printing sludge. The combination of flocculant and aluminum ash at this amount can better exert the flocculation effect of the flocculant, and more completely flocculate and settle the sludge, which is convenient for subsequent deep dewatering.

[0030] In a preferred embodiment, the aluminum ash is added in stages. A portion of the aluminum ash is added when the flocculant is added, and another portion is added after flocculation and sedimentation are complete, that is, before plate and frame filtration. The aluminum ash added first reacts with water and releases heat to promote the dissolution of the flocculant and the unfolding of molecular chains, thereby enhancing the flocculation effect of the flocculant. The aluminum ash added later can play a role during plate and frame filtration. The gas generated can form a drainage channel when it overflows, which facilitates the discharge of water and improves the dehydration effect.

[0031] Furthermore, in the above embodiments, aluminum ash is used as an additive for flocculation and sedimentation. During the process of promoting sludge dewatering, the soluble salts contained in aluminum ash, such as chloride salts, can dissolve in the water in the sludge and separate from the sludge during the dewatering process. Therefore, the chloride content of aluminum ash can be reduced, which facilitates the application of the dewatered sludge cake in cement production.

[0032] The main raw materials for cement production are limestone, clay, iron ore, and gypsum. Clay primarily provides Al2O3 and SiO2 for cement, reacting with limestone during sintering to form tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A), and tetracalcium aluminoferrite (C4AF), which form the main mineral phases of cement. Natural clay raw materials mainly include loess, clay, sandstone, and river sand. These raw materials have a high SiO2 content, mostly above 55%, and generally suffer from insufficient aluminum content, thus requiring the addition of aluminum-supplementing materials.

[0033] In this regard, a second aspect of the present invention also provides a high-alumina calorific value soil, which is obtained by drying and pulverizing dewatered cement cake. The dewatered cement cake is prepared by the aforementioned dewatering method for dyeing and printing sludge. Because a large amount of aluminum ash is added during the dewatering process, the aluminum content of the dewatered cement cake is high, thus it can be used as a raw material for cement production and has an aluminum-supplementing effect on cement. In preparing this high-alumina calorific value soil, the moisture content of the dewatered cement cake is first reduced to below 20% by drying, and then pulverized to obtain powdered high-alumina calorific value soil. Because aluminum ash and aluminum-containing flocculants are added during the preparation of this material, the alumina content in the mineral composition of the residue after burning at 800℃ is >23%, the organic matter content in the dry matter of this high-alumina calorific value clay is ≥25%, and its calorific value is ≥1300 kcal. Therefore, when used as a raw material for cement, it can replace part of the clay, greatly increase the aluminum content in the cement, and has an aluminum supplementation effect. In addition, the organic matter in this material can burn and release heat during the cement production process, thereby reducing the energy consumption during cement production.

[0034] The main clinker minerals of silicate cement are tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A), and tetracalcium aluminoferrite (C4AF). Among them, tricalcium silicate (3CaO·SiO2, C3S) is the main mineral in silicate cement clinker, generally accounting for 50% to 70% of the clinker mineral composition. However, C3S has a firing temperature of approximately 1450℃, a CaO content of 73.7%, and emits approximately 0.86 t / t of CO2 during firing, resulting in very high energy consumption and carbon emissions during cement sintering. Compared with C3S, minerals such as calcium sulfoaluminate (3CaO·3Al2O3·CaSO4, C4A3S) and dicalcium silicate (2CaO·SiO2, C2S) have the characteristics of lower firing temperature, lower CaO content, and lower CO2 emissions per unit mass. Therefore, reducing C3S content and increasing the content of minerals such as C2S and C4A3S, especially increasing the content of C4A3S, is an important way to reduce the energy consumption and carbon emissions of cement sintering. However, in current cement production, alumina is mainly provided by clay, but clay has a low aluminum content. Therefore, aluminum-adding materials need to be added to promote the formation of C4A3S minerals. Traditional aluminum-adding material, bauxite, is an aluminate and one of the important raw materials in cement production. High-alumina bauxite has a high Al2O3 content, which can adjust the aluminum content in cement clinker, enhance the early strength of cement, and lower the firing temperature. However, high-quality bauxite minerals are non-renewable resources and are expensive, resulting in high cement production costs. Therefore, it is necessary to develop new aluminum-adding materials, such as high-alumina calorific value clay, to reduce cement costs and energy consumption.

[0035] In response to this, a third aspect of the present invention provides a cement in which high-alumina calorific value clay, as described above, is added to the raw materials for preparing the cement. Utilizing the characteristic that the alumina content of this high-alumina calorific value clay is greater than 30%, the insufficient aluminum content in natural clay can be compensated for, facilitating the formation of tricalcium aluminate (C3A) and tetracalcium aluminoferrite (C4AF) during the cement sintering process. Furthermore, since this high-alumina calorific value clay contains a relatively large amount of organic matter, which can generate heat during sintering, energy consumption in the sintering process can be reduced. More importantly, by using high-alumina calorific value clay in cement production, the utilization rate of aluminum ash and dyeing sludge can be improved, the amount of natural clay used can be reduced, and the process is more environmentally friendly.

[0036] In a preferred embodiment, the amount of high-alumina calorific value clay added can be equal to or greater than the amount of clay added, preferably 5 to 15 wt%, thereby ensuring that the aluminum content in the cement meets the standard and facilitating the formation of mineral phases.

[0037] In a preferred embodiment, the raw materials for preparing the cement, by weight percentage, include: 80%–90% limestone, 5%–15% clay, 5%–15% high-alumina calorific value clay, 1%–2% iron ore powder, and <3% gypsum.

[0038] In a preferred embodiment, the raw materials for preparing the cement, by mass percentage, include: 83% limestone, 7% clay, 8% high-alumina calorific value clay, 1% iron ore powder, and 1% gypsum, wherein the high-alumina calorific value clay has an alumina content of 26%.

[0039] To further illustrate the present invention's method for dewatering dyeing sludge, high-alumina calorific value clay, and cement, the following embodiments are provided.

[0040] Example 1

[0041] A method for dewatering dyeing and printing sludge includes the following steps: adding flocculant and aluminum ash to the dyeing and printing sludge slurry by weight percentage, wherein the amount of flocculant added is 2% of the dry weight of the dyeing and printing sludge, and the amount of aluminum ash added is 25% of the dry weight of the dyeing and printing sludge; after flocculation and sedimentation, the sludge slurry is transferred to a plate and frame filter press, and dewatered sludge cake with a moisture content of 44% is obtained by plate and frame filtration. Figure 1 As shown.

[0042] The dewatered cake prepared in Example 1 was dried and pulverized to obtain high-alumina calorific value clay (such as...). Figure 3 As shown in Table 2, the specific composition of this high-alumina calorific value clay is as follows. The organic matter content on a dry basis is 30.04%, and the alumina content in the residue after ignition is 31.7%.

[0043] Table 2. Composition of high-alumina calorific value clay

[0044] Serial Number Ingredient name content(%) 1 Loss on ignition (1025℃) 30.04 2 <![CDATA[Aluminum oxide Al2O3]]> 31.70 3 <![CDATA[Silicon dioxide SiO2]]> 15.64 4 <![CDATA[Iron(III) oxide Fe2O3]]> 3.18 5 Calcium oxide (CaO) 4.81 6 Magnesium oxide (MgO) 1.20 7 Potassium oxide KO 0.25 8 <![CDATA[Sodium oxide Na20]]> 2.44 9 <![CDATA[Titanium dioxide TiO2]]> 0.08

[0045] Example 2

[0046] A method for dewatering dyeing and printing sludge includes the following steps: adding flocculant and aluminum ash to the dyeing and printing sludge slurry by weight percentage, wherein the amount of flocculant added is 2% of the dry weight of the dyeing and printing sludge, and the amount of aluminum ash added is 10% of the dry weight of the dyeing and printing sludge; after flocculation and sedimentation, adding 15% of the dry weight of aluminum ash to the sludge, stirring evenly, and then transferring the sludge slurry to a plate and frame filter press, and obtaining a dewatered sludge cake with a moisture content of 40% by plate and frame filtration.

[0047] The dewatered cake prepared in Example 2, after drying and pulverizing, yielded a high-alumina calorific value clay residue with an alumina content of 31.9%.

[0048] Example 3

[0049] A method for dewatering dyeing and printing sludge is disclosed. This method is essentially the same as the steps in Example 2, except that: the amount of flocculant added is 1% of the dry weight of the dyeing and printing sludge; the amount of aluminum ash added during flocculation is 15% of the dry weight of the dyeing and printing sludge; and the amount added after flocculation is 15% of the dry weight of the dyeing and printing sludge. The dewatering method yields a dewatered sludge cake with a moisture content of 45%.

[0050] After the dewatered cement cake is dried and crushed, the alumina content in the residue of the high-alumina calorific value soil after calcination is 35.2%.

[0051] Example 4

[0052] A method for dewatering dyeing and printing sludge is disclosed. This method is essentially the same as the steps in Example 2, except that the amount of flocculant added is 0.5% of the dry weight of the dyeing and printing sludge, the amount of aluminum ash added during flocculation is 8% of the dry weight of the dyeing and printing sludge, and the amount added after flocculation is 10% of the dry weight of the dyeing and printing sludge. The dewatering method yields a dewatered sludge cake with a moisture content of 53%.

[0053] After the dewatered cement cake was dried and crushed, the alumina content in the residue of the high-alumina calorific value clay after calcination was 23.27%.

[0054] The high-alumina calorific value clay prepared in Examples 1-3 was used to prepare cement. The specific raw materials for the cement were: 83% limestone, 7% clay, 8% high-alumina calorific value clay, 1% iron ore powder, and 1% gypsum. After sintering, cement meeting the requirements was obtained in Examples 1-3. When the high-alumina calorific value clay was the aluminum-supplementing material prepared in Example 4, the raw materials for preparing the cement were: 80% limestone, 3% clay, 15% high-alumina calorific value clay, 1% iron ore powder, and 1% gypsum. Ordinary silicate cement could be obtained by firing.

[0055] Comparative Example 1

[0056] A method for dewatering dyeing and printing sludge is disclosed. The method is essentially the same as that in Example 1, except that aluminum ash is not added. The dewatered sludge cake obtained by this method has a water content of 62%. Figure 2 As shown.

[0057] The dewatered cake prepared in Comparative Example 1 was dried to a moisture content of 20% and then crushed to obtain dyeing and printing sludge powder. Since the alumina content in the residue after burning of the dyeing and printing sludge powder was only 4.8%, it could not be used as a high alumina calorific value soil.

[0058] Comparative Example 2

[0059] A method for dewatering dyeing and printing sludge is disclosed. This method is essentially the same as the method in Example 1, except that the amount of aluminum ash added is 5% of the dry weight of the sludge. The dewatered sludge cake obtained by this method has a moisture content of 59%.

[0060] Comparative Example 3

[0061] A method for dewatering dyeing and printing sludge is disclosed. This method is essentially the same as the steps in Example 2, except that aluminum ash is not added during the addition of flocculant; instead, aluminum ash (15% of the dry weight of the sludge) is added only after flocculation. The dewatered sludge cake obtained by this method has a moisture content of 54%.

[0062] As shown in Examples 1-4, the method described in this invention can deeply dewater dyeing sludge. The moisture content of the dewatered sludge cake can be reduced to 40%, which is 22% lower than the existing plate and frame filter press dewatering method using flocculant in Comparative Example 1. Therefore, it can greatly reduce the energy consumption for subsequent sludge drying. Comparing Example 1 and Example 2, with the same total amount of flocculant and aluminum ash added, Example 2 has a higher dewatering rate. The main reason is that the hydrolysis of aluminum ash can play a corresponding role in both flocculation and plate and frame filter press, which facilitates the spread of flocculant and the formation of drainage channels. Comparing Example 1 and Comparative Example 2, when the amount of aluminum ash added is insufficient, its dewatering effect is not obvious. This may be because the amount of aluminum hydroxide produced by aluminum ash hydrolysis is too small, and also because the aluminum ash has been completely hydrolyzed during flocculation. Therefore, only a small amount of gas is discharged during plate and frame filter press, which cannot form drainage channels, resulting in an insignificant dewatering effect. Comparing Example 2 with Comparative Example 2, it was found that although adding aluminum ash only after flocculation can improve the dewatering effect of plate and frame filter press, its effect is significantly worse than that of Example 2. Therefore, it can be seen that only by adding aluminum ash during both flocculation and plate and frame filter press can a better dewatering effect be achieved.

[0063] In the description of the embodiments of the present invention, it should be noted that the terms "inner," "outer," "upper," "lower," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0064] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0065] It is understood that those skilled in the art can make equivalent substitutions or modifications to the technical solution and inventive concept of the present invention, and all such substitutions or modifications should fall within the protection scope of the appended claims.

Claims

1. A method for dewatering dyeing and printing sludge, characterized in that, The method includes the following steps: adding flocculant and aluminum ash to the sludge thickening stage of dyeing and printing sludge, stirring evenly to allow for full flocculation and sedimentation, and then performing plate and frame filtration to obtain dewatered sludge cake with a moisture content of 40-53%; a portion of the aluminum ash is added when adding the flocculant, and another portion is added after flocculation and sedimentation are complete; the flocculant includes one of polyaluminum sulfate, polyaluminum chloride, or polyacrylamide; the amount of aluminum ash added is 18-30% of the dry weight of the dyeing and printing sludge.

2. A high-alumina calorific value clay, characterized in that, The high-alumina calorific value soil is obtained by drying and crushing dewatered cement cake, which is prepared by the dewatering method for dyeing and printing sludge as described in claim 1.

3. The high-alumina calorific value clay according to claim 2, characterized in that, The high-alumina calorific value soil has an organic matter content of ≥25% in its dry matter and a calorific value of ≥1300 kcal; the alumina content in the mineral composition of the residue after burning at 800℃ is >23%.

4. A type of cement, characterized in that, The raw materials for preparing the cement contain high-alumina calorific value clay as described in claim 2 or 3.

5. The cement according to claim 4, characterized in that, The amount of high-alumina calorific value clay added to the cement raw materials is 5-15% by mass percentage.

6. The cement according to claim 5, characterized in that, The raw materials for preparing the cement, by mass percentage, include: 83% limestone, 7% clay, 8% high-alumina calorific value clay, 1% iron ore powder, and 1% gypsum.

Images