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

Abstract

The invention discloses a dyeing sludge dewatering method, high-alumina calorific value soil and cement, and relates to the technical field of sludge treatment. The method for dewatering the printing and dyeing sludge comprises the following steps: adding a flocculating agent and aluminum ash in a sludge concentration link of the printing and dyeing sludge, uniformly stirring to sufficiently flocculate and precipitate the printing and dyeing sludge, and performing plate-frame pressure filtration to obtain a printing and dyeing sludge-high-aluminum material composite dewatered cement cake with the water content of 40-53%. On one hand, a flocculating agent and aluminum ash are added in the slurry concentration link, heat generated by hydrolysis of the aluminum ash is utilized to promote the flocculating agent to be better expanded, and meanwhile, the aluminum ash meets water to produce aluminum hydroxide and improve the flocculation effect of the slurry, and on the other hand, in the plate-and-frame pressure filtration process, gas and heat generated by hydrolysis of aluminum nitride and aluminum carbide in the aluminum ash are utilized to improve the flocculation effect of the slurry. The gas can form a moisture channel in the mud cake during filter pressing, so that moisture can be conveniently pressed out, the moisture content of the dewatered mud cake is as low as 40%, and the dewatered mud cake contains a high-content aluminum element and can be used for manufacturing high-aluminum calorific value soil and cement.

Description

Technical Field

[0001] The invention relates to the technical field of sludge treatment, and in particular to a printing and dyeing sludge dehydration method, high-alumina calorific value soil and cement. Background Art

[0002] Printing and dyeing sludge is solid waste generated during the wastewater treatment process of the textile printing and dyeing industry, containing dyes, fabric hair, surfactants and other substances. At present, my country's textile printing and dyeing industry produces about 2.1 billion tons of wastewater each year. After treatment, these wastewaters produce about 21 million tons of printing and dyeing sludge. However, due to the high water content in printing and dyeing sludge, it is difficult to be recycled. In addition, traditional sludge treatment and disposal methods mainly include incineration, landfill, anaerobic digestion and land use, but these treatment methods are very likely to cause secondary pollution to the environment.

[0003] The existing dehydration method of printing and dyeing sludge usually adopts flocculation precipitation and then filter pressing to dehydrate. This dehydration method can reduce the water content of sludge to 60%, but cannot perform deep dehydration. The prior art also discloses a method of using aluminum ash to improve the dehydration effect of municipal sludge, which treats aluminum ash by mixing hexadecyl ammonium bromide and octadecyl dimethyl benzyl ammonium chloride, washes, filters and then dries to obtain modified aluminum ash; the modified aluminum ash is put into municipal sludge, and through stirring and precipitation, the solid particles and water in the sludge are separated; the solid and liquid materials after precipitation are filtered under a certain pressure to obtain a mud cake with a low water content. Compared with the sludge water content obtained by the currently commonly used dehydration process, this process greatly reduces the sludge water content, and the water content can be reduced 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 for multiple times, and needs to be dried at a high temperature of 90 to 110°C. The steps are cumbersome and energy-intensive.

[0004] It can be seen that the existing technology still needs to be improved and enhanced. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a method for dehydrating printing and dyeing sludge, high alumina calorific value soil and cement, aiming to solve the defect that the existing dehydration method is difficult to deeply dehydrate printing and dyeing sludge.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for dewatering printing and dyeing sludge, wherein the method comprises the steps of adding flocculant and aluminum ash in the printing and dyeing sludge slurry concentration link, stirring evenly to make it fully flocculate and precipitate, and then performing plate and frame filter pressing to obtain a dewatered sludge cake with a moisture content of 40-53%.

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

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

[0010] In the printing and dyeing sludge dewatering method, a part of the aluminum ash is added when the flocculant is added, and the other part of the aluminum ash is added after the flocculation and precipitation are complete.

[0011] A high-alumina calorific value soil, wherein the high-alumina calorific value soil is obtained by drying and crushing dehydrated water cake, and the dehydrated water cake is prepared by the above-mentioned printing and dyeing sludge dehydration method.

[0012] In the high-alumina calorific value soil, the content of organic matter in the dry matter of the high-alumina calorific value soil is ≥25%, and the calorific value is ≥1300 kcal; the content of alumina in the mineral composition of the residue after burning at 800°C is >23%.

[0013] A cement, wherein the high alumina calorific value soil as claimed in claim 5 or 6 is added to the raw materials for preparing the cement.

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

[0015] In the cement, the raw materials for preparing the cement include, by mass percentage, 83% limestone, 7% clay, 8% high-alumina calorific value soil, 1% iron ore powder, and 1% gypsum.

[0016] Beneficial effects:

[0017] The invention provides a method for dewatering printing and dyeing sludge. The method comprises the following steps: adding flocculant and aluminum ash in a sludge concentration link, utilizing the heat generated by the hydrolysis of aluminum ash to promote better dissolution of flocculant molecules and chain expansion, thereby improving the flocculation effect; at the same time, the aluminum hydroxide generated by the hydrolysis of aluminum ash also has a flocculation effect, thereby promoting the flocculation and precipitation of printing and dyeing sludge; on the other hand, in a plate and frame filter pressing process, utilizing the gas and heat generated by the hydrolysis of aluminum nitride and aluminum carbide in the aluminum ash, wherein these gases can form a through gas channel in the mud cake during the filter pressing, and the gas channel is used as a water filtering channel during the filter pressing, thereby facilitating the filtering out of water pressure inside the mud cake during the plate and frame filter pressing, thereby facilitating the removal of water and reducing the water content of the dewatered cement cake; on the other hand, the heat generated by the hydrolysis of aluminum nitride and aluminum carbide can also promote the formation of cracks inside the mud cake, thereby facilitating the pressing out of water inside the mud cake, replenishing water to the cement, thereby achieving the purpose of deep dehydration, thereby reducing the water content of the dewatered cement cake after the plate and frame filter pressing to 40%, and eliminating the hazardous waste property of the aluminum ash. The dehydrated cement cake prepared by the method can obtain an organic matter content of ≥25% and a calorific value of ≥800 kcal after drying and crushing; the high-aluminum calorific value material with an alumina content of >20% in the mineral composition of the residue after burning at 800°C is used in cement clinker production, which has the function of supplementing aluminum elements, reducing the consumption of high-aluminum bauxite minerals and reducing the energy consumption of cement clinker burning. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a physical picture of the dehydrated water cake prepared in Example 1 of the present invention.

[0019] Figure 2 This is a physical picture of the dehydrated cake prepared in Comparative Example 1.

[0020] Figure 3 This is a physical picture of the high alumina calorific value soil obtained in Example 1. DETAILED DESCRIPTION

[0021] The present invention provides a method for dehydrating printing and dyeing sludge, high alumina calorific value soil and cement. In order to make the purpose, technical scheme and effect of the present invention clearer and more specific, the present invention is further described in detail by the following embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] Since the moisture content of the dyeing sludge separated from the dyeing wastewater is as high as 96-99%, the existing dehydration by flocculation and mechanical filtration can only remove about 60% of the water. Figure 2As shown, the moisture content is still high, resulting in high energy consumption in the subsequent drying process and high recycling costs. In view of this problem, the present invention provides a method for dehydrating printing and dyeing sludge, which comprises the following steps: adding flocculants and aluminum ash to the concentration of printing and dyeing sludge, stirring them evenly to make them fully flocculate and precipitate, and then performing plate and frame filter pressing. Through the plate and frame filter pressing, a dehydrated water cake with a moisture content of 40-53% can be obtained, such as Figure 1 shown.

[0023] During the specific implementation process, the printing and dyeing sludge is usually placed in a concentrating tank, which is equipped with an exhaust device to absorb the odor generated by the printing and dyeing sludge and the gas generated by the hydrolysis of aluminum ash; before adding flocculants and aluminum ash to the printing and dyeing sludge, the proportion of dry mass of sludge in the printing and dyeing sludge can be measured first, and then flocculants and aluminum ash can be added according to the dry mass of sludge; during plate and frame filter pressing, an exhaust device is also provided to discharge the exhaust gas.

[0024] In this embodiment, by adding flocculant and aluminum ash in the mud concentration link, aluminum oxide, nitride and carbide contained in aluminum ash are utilized, especially secondary aluminum ash contains more aluminum nitride and aluminum carbide (the composition of aluminum ash is shown in Table 1). These components will produce gas when they meet water, and release a large amount of heat at the same time. Therefore, by adding aluminum ash in the flocculation and precipitation process, on the one hand, the hydrolysis reaction of aluminum ash is utilized to promote better development of flocculant, improve the flocculation effect, and aluminum hydroxide produced by the hydrolysis of aluminum ash also has a flocculation effect; on the other hand, in the plate and frame filter pressing process, the gas and heat generated when aluminum nitride and aluminum carbide are hydrolyzed are utilized. These gases can form water channels in the mud cake when overflowing, thereby facilitating the water to be drawn out during the plate and frame filter pressing, facilitating the removal of water, and improving the dehydration rate. On the other hand, the heat generated when aluminum nitride and aluminum carbide are hydrolyzed can promote the formation of cracks in the mud cake from the inside to the outside, facilitating the internal water to be pressed out, thereby achieving the purpose of deep dehydration, and the moisture content of the dehydrated mud cake after the plate and frame filter pressing can be reduced to 45%.

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

[0026] Serial number Element content Determination method 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] In addition, aluminum ash contains a large amount of aluminum oxides, nitrides and carbides, as well as salts (fluorides, chlorides, etc.), which makes aluminum ash react with water to generate gases such as CH4, H2S, NH3, and release heat violently. This is also the main reason why aluminum ash is listed as a hazardous waste (reactivity). This solution adds aluminum ash to the printing and dyeing sludge concentration tank. Since the water content in the slurry far exceeds the amount of aluminum ash, the heat generated by the reaction of aluminum ash with water will not significantly cause a sharp increase in water temperature. At the same time, the waste gas generated can be collected and treated together with the odor of printing and dyeing sludge, which greatly reduces the disposal cost of aluminum ash, eliminates the hazardous waste properties of aluminum ash, and makes its use safer.

[0028] In a preferred embodiment, the flocculant includes one of polyaluminium sulfate, polyaluminium chloride or polyacrylamide, which have a good flocculation effect on printing and dyeing sludge, and can quickly flocculate the printing and dyeing sludge into blocks, which is convenient for the removal of water. More preferably, the flocculant is polyaluminium sulfate or polyaluminium chloride, which contains aluminium, which can increase the aluminium content in the dewatered water cake, and facilitate the application of the dewatered water cake as high aluminium calorific value soil.

[0029] In a preferred embodiment, the added amount of the flocculant is 1-5% of the weight of the dry material of the printing and dyeing sludge, and the added amount of the aluminum ash is 18-30% of the weight of the dry material of the printing and dyeing sludge. The added amount of flocculant and aluminum ash are used in combination to better exert the flocculation effect of the flocculant, and the sludge is flocculated and precipitated more completely, which is convenient for subsequent deep dehydration.

[0030] In a preferred embodiment, the aluminum ash is added in steps, a part of the aluminum ash is added when the flocculant is added, and the other part of the aluminum ash is added after the flocculation and precipitation are complete, that is, it is added before the plate and frame filter press. The first part of the aluminum ash reacts with water to release heat to promote the dissolution of the flocculant and the expansion of the molecular chain, thereby enhancing the flocculation effect of the flocculant; and the aluminum ash added later can play a role during the plate and frame filter press, and the generated gas can form a drainage channel when it overflows, thereby facilitating the discharge of water and improving the dehydration effect.

[0031] In addition, in the above embodiment, aluminum ash is used as a flocculation and precipitation aid. In the process of promoting sludge dehydration, soluble salts contained in the aluminum ash, such as chloride salts, can be dissolved in the water in the mud and separated from the mud during the dehydration process. Therefore, the chlorine content of the aluminum ash can be reduced, which facilitates the use of the dehydrated mud cake in cement production.

[0032] Since the main raw materials for the existing cement production are limestone, clay, iron ore, gypsum, etc., among which the clay mainly provides Al2O3 and SiO2 for cement, which reacts with limestone during the sintering process to form tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A) and tetracalcium aluminoferrite (C4AF), forming the main mineral phase of cement. Natural clay raw materials mainly include loess, clay, sandstone, river sand, etc. The content of SiO2 in these raw materials is relatively high, mostly above 55%, and basically there is a problem of insufficient aluminum content, so additional aluminum supplement materials need to be added.

[0033] In this regard, the second aspect of the present invention further provides a high-aluminum calorific value soil, which is obtained by drying and crushing dehydrated water cake, wherein the dehydrated water cake is a dehydrated water cake prepared by the aforementioned printing and dyeing sludge dehydration method, and since a large amount of aluminum ash is added to the dehydrated water cake during the dehydration process, the aluminum content is relatively high, and thus the dehydrated water cake can be used as a raw material for cement production, and has an aluminum supplement effect on cement. When preparing the high-aluminum calorific value soil, the moisture content of the dehydrated water cake is first reduced to less than 20% by drying, and then crushed to obtain a powdery high-aluminum calorific value soil. Since aluminum ash and aluminum-containing flocculants are added to the material during its preparation, the content of aluminum oxide in the mineral composition of the residue after burning at 800°C is greater than 23%, the content of organic matter in the dry matter of the high-aluminum calorific value soil 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 supplement effect; in addition, the organic matter in the 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 Portland 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 Portland cement clinker, generally accounting for 50% to 70% of the clinker mineral composition. However, the sintering temperature of C3S is about 1450℃, its CaO content accounts for 73.7%, and the amount of CO2 emitted during sintering is about 0.86t / t, which leads to very high energy consumption and large 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 low sintering temperature, low CaO content and low CO2 emissions per unit mass. Therefore, reducing the C3S content, increasing the content of minerals such as C2S and C4A3S, especially increasing the C4A3S mineral content, is an important way to reduce cement sintering energy consumption and carbon emissions. However, among the existing raw materials for preparing cement, alumina is mainly provided by clay, but the aluminum content in clay is low, so aluminum-supplementing materials need to be added to promote the formation of C4A3S minerals. The traditional aluminum-supplementing 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 reduce the firing temperature of cement. However, high-quality bauxite minerals are non-renewable resources and are expensive, which makes the cost of cement production high. Therefore, it is necessary to develop new aluminum-supplementing materials, such as high-alumina calorific value soil, to reduce cement costs and energy consumption.

[0035] In this regard, the third aspect of the present invention provides a cement, wherein the raw materials for preparing the cement are added with the high-alumina soil as described above, and the high-alumina soil has a content of alumina greater than 30%, which can make up for the problem of insufficient aluminum content in natural clay, and facilitate the formation of tricalcium aluminate (C3A) and tetracalcium aluminoferrite (C4AF) in the cement during the sintering process. In addition, since the high-alumina soil contains more organic matter, these organic matters can generate heat during the sintering process, thereby reducing the energy consumption of the sintering process. More importantly, by using the high-alumina soil in cement production, the utilization rate of aluminum ash and printing and dyeing sludge can be improved, the use of natural clay can be reduced, and it is more environmentally friendly.

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

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

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

[0039] To further illustrate the printing and dyeing sludge dehydration method, high alumina calorific value soil and cement provided by the present invention, the following examples are provided.

[0040] Example 1

[0041] A method for dehydrating printing and dyeing sludge, the method comprising the steps of: adding flocculants and aluminum ash to printing and dyeing sludge slurry by mass percentage, wherein the amount of flocculants added is 2% of the dry mass of the printing and dyeing sludge, and the amount of aluminum ash added is 25% of the dry mass of the printing and dyeing sludge; after flocculation and precipitation, transferring the sludge concentrated slurry to a plate-frame filter press, and obtaining a dehydrated water cake with a water content of 44% by plate-frame filter press, such as Figure 1 shown.

[0042] The dehydrated cake prepared in Example 1 was dried and crushed to obtain a high aluminum calorific value soil (such as Figure 3 The specific composition of the high aluminum calorific value soil is shown in Table 2. The organic matter content in the dry basis is 30.04%, and the aluminum oxide content in the residue after burning is 31.7%.

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

[0044] Serial number Ingredient name content(%) 1 Loss on ignition (LOSS) (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 dehydrating printing and dyeing sludge comprises the following steps: adding flocculant and aluminum ash to printing and dyeing sludge slurry by mass percentage, wherein the added amount of flocculant is 2% of the dry mass of printing and dyeing sludge, and the added amount of aluminum ash is 10% of the dry mass of printing and dyeing sludge; after flocculation and sedimentation, adding aluminum ash of 15% of the dry mass of sludge, stirring evenly, transferring the sludge concentrated slurry to a plate and frame filter press, and obtaining a dehydrated water cake with a water content of 40% by plate and frame filter pressing.

[0047] The dehydrated water cake prepared in Example 2 is dried and crushed, and the residue after burning the high-alumina calorific value soil has an alumina content of 31.9%.

[0048] Example 3

[0049] A method for dehydrating printing and dyeing sludge, the method is basically the same as the steps of Example 2, except that: the amount of flocculant added is 1% of the dry mass of the printing and dyeing sludge, the amount of aluminum ash added during flocculation is 15% of the dry mass of the printing and dyeing sludge, and the amount of aluminum ash added after flocculation is 15% of the dry mass of the printing and dyeing sludge. The moisture content of the dehydrated cake prepared by the dehydration method is 45%.

[0050] The dehydrated water cake is dried and crushed to obtain a residue with a high aluminum calorific value after burning, and the aluminum oxide content is 35.2%.

[0051] Example 4

[0052] A method for dehydrating printing and dyeing sludge, the method is basically the same as the steps of Example 2, except that: the amount of flocculant added is 0.5% of the dry mass of the printing and dyeing sludge, the amount of aluminum ash added during flocculation is 8% of the dry mass of the printing and dyeing sludge, and the amount added after flocculation is 10% of the dry mass of the printing and dyeing sludge. The moisture content of the dehydrated cake prepared by the dehydration method is 53%.

[0053] The dehydrated water cake is dried and crushed, and the residue after burning the high-alumina calorific value soil has an alumina content of 23.27%.

[0054] The high alumina calorific value soil prepared in Examples 1-3 is used to prepare cement, and the raw materials of the cement are specifically: 83% limestone, 7% clay, 8% high alumina calorific value soil, 1% iron ore powder, and 1% gypsum. After sintering, Examples 1-3 can all obtain cement that meets the requirements. When the high alumina calorific value soil is the aluminum supplement material prepared in Example 4, the raw materials for preparing the cement are: 80% limestone, 3% clay, 15% high alumina calorific value soil, 1% iron ore powder, and 1% gypsum. After sintering, ordinary silicate cement can be obtained.

[0055] Comparative Example 1

[0056] A method for dehydrating printing and dyeing sludge, the method is basically the same as the steps of Example 1, except that no aluminum ash is added. The moisture content of the dehydrated sludge cake obtained by the method is 62%. Figure 2 shown.

[0057] The dehydrated water cake prepared in Comparative Example 1 is dried to a moisture content of 20%, and then crushed to obtain printing and dyeing sludge powder. Since the aluminum oxide content in the residue after burning the printing and dyeing sludge powder is only 4.8%, it cannot be used as high aluminum calorific value soil.

[0058] Comparative Example 2

[0059] A method for dehydrating printing and dyeing sludge, the method is basically the same as the steps of Example 1, except that the amount of aluminum ash added is 5% of the dry mass of the sludge. The moisture content of the dehydrated sludge cake obtained by the method is 59%.

[0060] Comparative Example 3

[0061] A method for dehydrating printing and dyeing sludge, the method is basically the same as the steps of Example 2, except that: aluminum ash is not added when adding flocculants, and aluminum ash of 15% of the dry weight of sludge is added only after flocculation. The moisture content of the dehydrated sludge cake obtained by this method is 54%.

[0062] It can be seen from Examples 1-4 that the method of the present invention can be used to deeply dehydrate printing and dyeing sludge, and the moisture content of the dehydrated mud cake after dehydration can be reduced to 40%. Compared with the method of adding flocculants in plate and frame filter pressing dehydration in the existing comparative example 1, its moisture content can be reduced by 22%, so the energy consumption of subsequent sludge drying can be greatly reduced. Compared with Example 1, when the overall addition amount of flocculants and aluminum ash is the same, Example 2 has a higher dehydration rate. The main reason is that the hydrolysis of aluminum ash can play a corresponding role in flocculation and plate and frame filter pressing, which is convenient for the development of flocculants on the one hand and for the formation of drainage channels on the other hand. Compared with Example 1 and Comparative Example 2, it can be seen that when the addition amount of aluminum ash is insufficient, the dehydration effect it plays is not obvious. It may be that the aluminum hydroxide produced by the hydrolysis of aluminum ash is too little, and at the same time, because the aluminum ash has been completely hydrolyzed during flocculation, only a small amount of gas is discharged during the plate and frame filter pressing, and a drainage channel cannot be formed, resulting in an insignificant dehydration effect. Comparing Example 2 with Comparative Example 2, it is found that although adding aluminum ash only after flocculation can improve the dehydration effect of plate and frame filter pressing, its effect is significantly worse than that of Example 2. This shows that only by adding aluminum ash during flocculation and plate and frame filter pressing can a better dehydration effect be achieved.

[0063] In the description of the embodiments of the present invention, it should be noted that the terms "inside", "outside", "upper", "lower", "left", "right", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when 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, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0064] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0065] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the claims attached to the present invention.

Claims

1. A method for dewatering printing and dyeing sludge, characterized in that: The method comprises the steps of adding flocculant and aluminum ash in the concentration link of printing and dyeing sludge, stirring evenly to make it fully flocculate and precipitate, and then performing plate and frame filter pressing to obtain dehydrated water cake with a water content of 40-53%.

2. The method for dewatering printing and dyeing sludge according to claim 1, characterized in that: The flocculant includes one of polyaluminium sulfate, polyaluminium chloride or polyacrylamide.

3. The method for dewatering printing and dyeing sludge according to claim 1, characterized in that: The added amount of the aluminum ash is 18-30% of the weight of the dry printing and dyeing sludge.

4. The method for dewatering printing and dyeing sludge according to claim 1, characterized in that: A portion of the aluminum ash is added when the flocculant is added, and the other portion of the aluminum ash is added after the flocculation and sedimentation are complete.

5. A high alumina calorific value soil, characterized in that: The high-alumina calorific value soil is obtained by drying and crushing dehydrated water cake, and the dehydrated water cake is prepared by the printing and dyeing sludge dehydration method according to any one of claims 1 to 4.

6. The high alumina calorific value soil according to claim 5, characterized in that: The organic matter content in the dry matter of the high-aluminum calorific value soil is ≥25%, and the calorific value is ≥1300 kcal; the aluminum oxide content in the mineral composition of the residue after burning at 800°C is greater than 23%.

7. A cement, characterized in that: The high alumina calorific value soil as claimed in claim 5 or 6 is added to the raw materials for preparing the cement.

8. The cement according to claim 7, characterized in that In terms of mass percentage, the addition amount of the high-alumina calorific value soil in the cement raw material is 5-15%.

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

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