A kind of sludge autoclaved brick and preparation method thereof

Abstract

The present invention discloses a sludge autoclaved brick and a preparation method thereof, belonging to the technical field of solid waste disposal. The sludge autoclaved brick is prepared from the following raw materials in parts by weight: 50-80 parts of sludge, 0-10 parts of lime, 5-15 parts of blast furnace slag, 0-5 parts of alkali residue, 0-20 parts of stone powder, 10-20 parts of electric furnace slag, 2-5 parts of desulfurized gypsum, 1-5 parts of silica fume, 0-10 parts of fly ash, 3-8 parts of cement, 0.5-0.01 parts of polycarboxylate water reducer, 0.1-0.01 parts of alkali activator, and 8-12 parts of water. The present invention (1) uses silt, stone powder, electric furnace slag and the like to prepare steam-cured bricks, which uses a large amount of solid waste and can not only deal with the problem of solid waste accumulation, but also turn waste into treasure and realize comprehensive resource utilization; (2) is prepared by a pressing steam-curing process, which has a simple process and convenient production; (3) adopts a burning-free technology, which does not generate air pollution, can also achieve energy-saving and carbon-reduction effects, and has significant ecological benefits; (4) the prepared autoclaved bricks have the advantages of long life, high strength and stable product performance, and can realize the production of steam-cured bricks of different specifications and sizes.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste disposal and relates to a sludge autoclaved brick, in particular to a sludge autoclaved brick and a preparation method thereof. Background Art

[0002] With the rapid advancement of urbanization, large amounts of construction debris and mud are generated during urban construction excavation. River dredging also produces large amounts of river silt. Furthermore, coastal cities also produce large amounts of marine silt. Due to its high water content and high impurity content, this silt is difficult to handle. Currently, most silt is disposed of through land reclamation or storage on vacant land, which often has adverse impacts on the social environment.

[0003] At present, the resource utilization of silt is mainly used to prepare sintered bricks and static pressed bricks. The preparation process of sintered bricks consumes a lot of energy and produces a large amount of waste gas, which affects the ecological environment. The amount of silt disposed of in the preparation of static pressed bricks is relatively small, and when the silt addition reaches 50%, it will seriously affect the mechanical properties and frost resistance of the static pressed bricks, resulting in unqualified product quality.

[0004] Therefore, there is an urgent need for a method for preparing new autoclaved bricks using silt to solve the above problems. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the prior art and provide a sludge autoclaved brick and a method for preparing the same. This invention overcomes the existing difficulty of limited sludge utilization and enables the coordinated utilization of a large number of various industrial solid wastes to produce autoclaved brick products with long life, high strength, and stable performance, and to achieve industrialized production of the products.

[0006] The specific technical solutions adopted in the present invention are as follows:

[0007] In a first aspect, the present invention provides a sludge autoclaved brick, which is prepared from the following raw materials in parts by weight:

[0008] 50-80 parts of silt, 0-10 parts of lime, 5-15 parts of blast furnace slag, 0-5 parts of alkali residue, 0-20 parts of stone powder, 10-20 parts of electric furnace slag, 2-5 parts of desulfurization gypsum, 1-5 parts of silica fume, 0-10 parts of fly ash, 3-8 parts of cement, 0.5-0.01 parts of polycarboxylic acid water reducer, 0.1-0.01 parts of alkali activator, and 8-12 parts of water.

[0009] Preferably, the particle size of the stone powder is less than 0.075 mm.

[0010] Preferably, the particle size of the electric furnace slag is less than 4.75 mm.

[0011] In a second aspect, the present invention provides a method for preparing sludge autoclaved bricks, which is as follows:

[0012] S1: Pre-treating sludge, stone powder, fly ash, blast furnace slag, alkali residue and desulfurization gypsum;

[0013] S2: 0-10 parts of lime, 10-20 parts of electric furnace slag, 1-5 parts of silica fume, 3-8 parts of cement, 0.5-0.01 parts of polycarboxylate water reducer, 0.1-0.01 parts of alkali activator, 8-12 parts of water, 0-20 parts of pretreated stone powder, 0-10 parts of fly ash, 2-5 parts of desulfurized gypsum, 50-80 parts of sludge, 5-15 parts of blast furnace slag and 0-5 parts of alkali residue are mixed and stirred to obtain a mixture;

[0014] S3: placing the mixture into a mold and pressing it into shape using a static press;

[0015] S4: placing the pressed bricks into an autoclave curing device for static curing;

[0016] S5: placing the bricks after static curing in an autoclave, and performing a hydrothermal reaction under high temperature and high pressure to obtain silt autoclaved bricks.

[0017] Preferably, in step S1, the sludge is dehydrated by filter pressing and naturally dried to reduce its moisture content to less than 20%, and the sludge, stone powder, fly ash, blast furnace slag, alkali residue and desulfurization gypsum are pretreated by ball milling to reduce their particle sizes to less than 0.075 mm.

[0018] Preferably, in step S2, the polycarboxylate water-reducing agent is evenly mixed with water to obtain a mixed liquid; stone powder, electric furnace slag, silica fume, fly ash, cement, alkali activator, lime, desulfurization gypsum, sludge, blast furnace slag and alkali residue are mixed and stirred for 5 to 15 minutes, and then the mixed liquid is added, and the mixing and stirring is continued for 3 to 5 minutes at a stirring rate of more than 300 r / min to obtain a mixture.

[0019] Preferably, in step S3, the pressure during compression molding is controlled between 10 and 20 MPa.

[0020] Preferably, in step S4, the static curing is to place the bricks in an environment with a temperature of 30-50° C. and a humidity of 50% RH-70% RH for 1-3 days.

[0021] Preferably, in step S5, the hydrothermal reaction temperature is 160-220° C., the pressure is 0.8-1.4 MPa, and the time is 3-6 hours.

[0022] Preferably, in step S5, the bricks after static curing are placed in an autoclave, and the autoclave is heated stepwise to the hydrothermal reaction temperature, specifically as follows: gradually heating from room temperature to 50°C, with a heating time of 10 to 30 minutes; gradually heating from 50°C to 100°C, with a heating time of 30 to 120 minutes; gradually heating from 100°C to 150°C, with a heating time of 60 to 180 minutes; and gradually heating from 150°C to the hydrothermal reaction temperature, with a heating time of 30 to 90 minutes.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention has a high solid waste utilization rate. Most of the raw materials are various types of construction and industrial solid waste. The solid waste utilization rate can reach more than 95%, avoiding the accumulation of large amounts of solid waste to cause environmental pollution.

[0025] 2. The product of the present invention has stable performance. After steam curing, the compressive strength reaches 35MPa, the softening coefficient is 1.0, the drying shrinkage is 0.03%, and the strength loss rate after freeze-thaw cycles is 10%, all of which are higher than general silt static pressure bricks.

[0026] 3. The present invention uses a static stop process to effectively improve product stability, making it less likely to crack, and the product stability can reach over 99%.

[0027] 4. The present invention systematically studies various types of construction solid waste and industrial solid waste, and utilizes them in a coordinated manner, thereby improving the level of resource utilization and solving the problem of alkaline slag, electric furnace slag and the like being unable to be utilized.

[0028] 5. The present invention can effectively solidify heavy metals in electric furnace slag through the autoclave curing process, thereby reducing heavy metal pollution. DETAILED DESCRIPTION

[0029] The present invention will be further described and illustrated below in conjunction with specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly without conflict.

[0030] In the present invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. The methods in the following examples are all conventional methods in the art unless otherwise specified.

[0031] The sludge autoclaved brick provided by the present invention is mainly prepared from the following raw materials in parts by weight: 50-80 parts of sludge, 0-10 parts of lime, 5-15 parts of blast furnace slag, 0-5 parts of alkali residue, 0-20 parts of stone powder with a particle size of less than 0.075 mm, 10-20 parts of electric furnace slag with a particle size of less than 4.75 mm, 2-5 parts of desulfurized gypsum, 1-5 parts of silica fume, 0-10 parts of fly ash, 3-8 parts of cement, 0.5-0.01 parts of polycarboxylic acid water reducer, 0.1-0.01 parts of alkali activator, and 8-12 parts of water.

[0032] Among them, the addition of stone powder, silica fume and fly ash is to ensure sufficient active silicon content during the hydrothermal reaction in the preparation process; the addition of lime is to ensure sufficient effective calcium content during the hydrothermal reaction in the preparation process; the addition of electric furnace slag is used as the aggregate structure of autoclaved bricks to ensure that the autoclaved bricks have higher strength; the addition of desulfurized gypsum is to reduce the heat generation rate of the reaction and ensure the stability of the autoclaved bricks; the addition of alkali activator is to ensure better stimulation of silicon-calcium hydrothermal reaction during the preparation process; the addition of blast furnace slag and alkali slag is to provide the calcium content required for the reaction; cement is used as a gelling agent to ensure a certain early strength in the early stage; the addition of polycarboxylic acid water reducer has a water-reducing effect and also has the effect of improving product strength.

[0033] The preparation method of the above-mentioned silt autoclaved brick is as follows:

[0034] S1 Raw material pretreatment:

[0035] ① Dehydrate and dry the salvaged silt.

[0036] It is preferred to reduce the moisture content of the sludge to less than 20% by filter pressing dehydration and natural drying.

[0037] ② Pre-treat the sludge, stone powder, fly ash, blast furnace slag, alkali residue and desulfurization gypsum by ball milling respectively.

[0038] By ball milling the above raw materials, 90% of the raw material particles have a particle size of less than 0.075mm. Ball milling improves the activity of silicon and calcium in the raw materials, ensuring that silicon and calcium undergo hydrothermal reaction under certain conditions.

[0039] Preparation of S2 mixture:

[0040] All raw materials are mixed and stirred to obtain a mixture. This step is preferably carried out in the following manner:

[0041] The polycarboxylate water reducer is uniformly mixed with water to obtain a mixed liquid; stone powder, electric furnace slag, silica fume, fly ash, cement, alkali activator, lime, desulfurized gypsum, sludge, blast furnace slag and alkali residue are mixed and stirred for 5 to 15 minutes, and then the mixed liquid is added, and the mixing and stirring is continued for 3 to 5 minutes at a stirring rate of more than 300 r / min to obtain a mixture.

[0042] In the above two steps, the sludge is subjected to ball milling (step S1) and alkali activation (i.e., mixing with an alkali activator in step S2) to increase the effective silicon content in the raw material, so that the pretreated sludge partially or completely replaces fly ash, fine sand, etc. in a hydrothermal solidification reaction with lime in the subsequent process.

[0043] Similarly, in the above two steps, the blast furnace slag and alkaline slag are subjected to ball milling (step S1) and alkali activation (i.e., mixing with an alkali activator in step S2) to increase the effective calcium content in the raw materials, and the pretreated solid waste is used to partially or completely replace the lime for hydrothermal solidification reaction.

[0044] To ensure the formation of tobermorite during the subsequent hydrothermal reaction, the calcium-silicon ratio in the mixture is maintained between 0.5 and 0.8, with a preferred ratio of 0.75. When the calcium-silicon ratio is 0.75, the compressive strength of the autoclaved brick reaches 35 MPa and the softening coefficient is 1.0, indicating the best quality brick.

[0045] S3 Compression Molding:

[0046] The stirred mixture is placed into a mold and pressed into shape using a static press.

[0047] The pressure during compression molding is preferably controlled between 10 and 20 MPa. This is because if the molding pressure is too low, the density will be insufficient and the mechanical properties will be affected. If the pressure is too high, the product will be difficult to demould and prone to cracking.

[0048] S4 static maintenance:

[0049] The pressed bricks are placed in autoclave curing equipment and cured at a certain temperature and humidity.

[0050] For static curing, the bricks are preferably placed in an environment with a temperature of 30-50°C and a humidity of 50% RH-70% RH for 1-3 days.

[0051] The above temperature and humidity conditions are used because, under these conditions, free water is distributed within the bricks. Over time, this free water can flow from moist areas to dry areas within the brick's pores, ultimately becoming evenly distributed throughout the pores, ensuring their continuity and stability. Static curing also allows for intermolecular forces to fully bond tiny particles to the water film over a period of time, enhancing strength.

[0052] The above-mentioned static time is adopted to ensure that the free water is stably distributed in the microporous structure of the brick, so that the free water can be evenly evaporated in the form of water vapor under subsequent steaming conditions to ensure the stability of the internal structure of the brick.

[0053] S5 autoclave curing:

[0054] After static curing, the bricks are placed in an autoclave and subjected to hydrothermal reaction under high temperature and high pressure to obtain silt autoclaved bricks.

[0055] Specifically, the bricks after static curing are placed in an autoclave, and the autoclave is heated stepwise to the hydrothermal reaction temperature as follows: gradually heating from room temperature to 50°C for 10 to 30 minutes; gradually heating from 50°C to 100°C for 30 to 120 minutes; gradually heating from 100°C to 150°C for 60 to 180 minutes; and gradually heating from 150°C to the hydrothermal reaction temperature for 30 to 90 minutes. The hydrothermal reaction temperature is 160 to 220°C, the pressure is 0.8 to 1.4 MPa, and the reaction time is 3 to 6 hours.

[0056] In the present invention, sludge with a silicon oxide content of 50% or more is preferred, while blast furnace slag and alkaline slag preferably contain at least 40% calcium. Furthermore, by pre-treating these solid wastes and then adding alkaline activators such as water glass and sodium hydroxide, the effective silicon and calcium contents in the reaction can be increased. These react hydrothermally to form tobermorite, improving product performance.

[0057] The effects of the bricks obtained by the method of the present invention will be further illustrated below through examples and comparative examples.

[0058] Example 1

[0059] This embodiment prepares a sludge autoclaved brick, and the preparation method is as follows:

[0060] S1. Raw material pretreatment

[0061] S11, reducing the moisture content of the sludge after filter pressing and dehydration to below 40%, and then reducing the moisture content to below 20% by natural drying, and then placing the sludge in a ball mill and milling it, and sieving it with a 0.075mm square hole sieve, and taking the sludge below 0.075mm for use;

[0062] S12, placing the blast furnace slag in a ball mill and grinding it, taking particles with a particle size of less than 0.075 mm after ball milling for later use;

[0063] S13, putting the desulfurized gypsum into a ball mill and grinding it, taking particles with a particle size of less than 0.075 mm after ball milling for later use;

[0064] S14, drying the alkali residue and placing it in a ball mill, and taking particles with a particle size of less than 0.075 mm after ball milling for later use;

[0065] S15, after drying the stone powder, put it into a ball mill and grind it, and take the particles with a particle size of less than 0.075 mm after ball milling for use;

[0066] S16, after drying the fly ash, put it into the ball mill and grind it, and take the particles with a particle size of less than 0.075mm after ball milling for use. S2, Mixture Preparation

[0067] S21, weigh 65 parts of silt, 2 parts of silica fume, 3 parts of fly ash, 2 parts of stone powder, 5 parts of blast furnace slag, 3 parts of alkaline slag, 10 parts of electric furnace slag, 2 parts of desulfurized gypsum, 5 parts of lime, 3 parts of cement, 0.005 parts of alkali activator, put them into a blender and stir for 10 minutes to mix all the raw materials evenly to form a pre-mixed material;

[0068] S22, weighing 0.01 parts of polycarboxylate water reducer and 10 parts of water, and mixing the polycarboxylate water reducer and water to obtain a mixed solution;

[0069] S23. Pour the mixed liquid into the prepared mixed material, and stir rapidly for 5 minutes at a stirring rate of 350 r / min to obtain a mixed material.

[0070] S3, compression molding

[0071] The evenly stirred mixture was poured into a mold and pressed into a test block using a static pressure molding method with a controlled pressure of 20 MPa and a holding time of 30 seconds.

[0072] S4. Static maintenance

[0073] The pressed test blocks were placed in a curing room at a curing temperature of 40±2°C and a humidity of 6%RH 0±5%RH for 24 hours.

[0074] S5. Autoclave curing

[0075] The test blocks after static curing were placed in a steam curing furnace, and the temperature was raised from room temperature to 50°C within 30 minutes, to 100°C within 90 minutes, to 150°C within 120 minutes, and to 180°C within 60 minutes; then, they were autoclaved and cured at 180°C and a pressure of 1.0 MPa for 4 hours to form sludge autoclaved bricks.

[0076] After characterization, it was found that the density of the product prepared in this embodiment was 1800 kg / m 3 , compressive strength 25MPa, softening coefficient 1.00, frost resistance strength loss 12%, drying shrinkage 0.03%, leaching toxicity meets the requirements of lead ≤ 2mg / L, cadmium ≤ 0.1mg / L, mercury ≤ 0.02mg / L, arsenic ≤ 0.5mg / L, nickel ≤ 0.5mg / L, copper ≤ 10mg / L, zinc ≤ 10mg / L, chromium ≤ 1.5mg / L.

[0077] Example 2

[0078] In this embodiment, a silt autoclaved brick is prepared. The preparation method is the same as that in Example 1, except that the amount of silt is 80 parts, the stone powder is 0 parts, and the fly ash is 0 parts.

[0079] After characterization, it was found that the density of the product obtained in this embodiment was 1600 kg / m 3 , compressive strength 15MPa, softening coefficient 0.88, frost resistance loss 18%, drying shrinkage 0.05%, leaching toxicity meets the requirements of lead ≤ 2mg / L, cadmium ≤ 0.1mg / L, mercury ≤ 0.02mg / L, arsenic ≤ 0.5mg / L, nickel ≤ 0.5mg / L, copper ≤ 10mg / L, zinc ≤ 10mg / L, chromium ≤ 1.5mg / L.

[0080] Example 3

[0081] In this embodiment, a sludge autoclaved brick is prepared. The preparation method is the same as that in Example 1, except that 55 parts of sludge and 20 parts of electric furnace slag are used.

[0082] After characterization, it was found that the density of the product obtained in this embodiment was 1850 kg / m 3 , compressive strength 35MPa, softening coefficient 1.20, frost resistance strength loss 8%, drying shrinkage 0.02%, leaching toxicity meets the requirements of lead ≤ 2mg / L, cadmium ≤ 0.1mg / L, mercury ≤ 0.02mg / L, arsenic ≤ 0.5mg / L, nickel ≤ 0.5mg / L, copper ≤ 10mg / L, zinc ≤ 10mg / L, chromium ≤ 1.5mg / L.

[0083] Example 4

[0084] In this embodiment, a silt autoclaved brick is prepared. The preparation method is the same as that in Example 1, except that 50 parts of silt and 15 parts of stone powder are used.

[0085] After characterization, it was found that the density of the product obtained in this embodiment was 1850 kg / m 3 , compressive strength 30MPa, softening coefficient 1.10, frost resistance loss 8%, drying shrinkage 0.03%, leaching toxicity meets the requirements of lead ≤ 2mg / L, cadmium ≤ 0.1mg / L, mercury ≤ 0.02mg / L, arsenic ≤ 0.5mg / L, nickel ≤ 0.5mg / L, copper ≤ 10mg / L, zinc ≤ 10mg / L, chromium ≤ 1.5mg / L.

[0086] Example 5

[0087] In this embodiment, a sludge autoclaved brick is prepared. The preparation method is the same as that in Example 1, except that 0 parts of stone powder, 7 parts of blast furnace slag, 5 parts of alkali residue and 3 parts of desulfurized gypsum are used.

[0088] After characterization, it was found that the density of the product obtained in this embodiment was 1800 kg / m 3, compressive strength 18MPa, softening coefficient 0.95, frost resistance strength loss 13%, drying shrinkage 0.04%, leaching toxicity meets the requirements of lead ≤ 2mg / L, cadmium ≤ 0.1mg / L, mercury ≤ 0.02mg / L, arsenic ≤ 0.5mg / L, nickel ≤ 0.5mg / L, copper ≤ 10mg / L, zinc ≤ 10mg / L, chromium ≤ 1.5mg / L.

[0089] Example 6

[0090] In this embodiment, a sludge autoclaved brick is prepared. The preparation method is the same as that in Example 1, except that 13 parts of blast furnace slag, 0 parts of alkali slag, and 0 parts of lime are used.

[0091] After characterization, it was found that the density of the product obtained in this embodiment was 1800 kg / m 3 , compressive strength 20MPa, softening coefficient 0.09, frost resistance strength loss 14%, drying shrinkage 0.05%, leaching toxicity meets the requirements of lead ≤ 2mg / L, cadmium ≤ 0.1mg / L, mercury ≤ 0.02mg / L, arsenic ≤ 0.5mg / L, nickel ≤ 0.5mg / L, copper ≤ 10mg / L, zinc ≤ 10mg / L, chromium ≤ 1.5mg / L.

[0092] Example 7

[0093] In this embodiment, a sludge autoclaved brick is prepared. The preparation method is the same as that in Example 1, except that 0.01 part of the alkali activator is used.

[0094] After characterization, it was found that the density of the product obtained in this embodiment was 1800 kg / m 3 , compressive strength 28MPa, softening coefficient 1.00, frost resistance strength loss 11%, drying shrinkage 0.03%, leaching toxicity meets the requirements of lead ≤ 2mg / L, cadmium ≤ 0.1mg / L, mercury ≤ 0.02mg / L, arsenic ≤ 0.5mg / L, nickel ≤ 0.5mg / L, copper ≤ 10mg / L, zinc ≤ 10mg / L, chromium ≤ 1.5mg / L.

[0095] Example 8

[0096] In this embodiment, a sludge autoclaved brick is prepared. The preparation method is the same as that in Example 1, except that the particle size of the sludge particles is less than 4.75 mm.

[0097] After characterization, it was found that the density of the product obtained in this embodiment was 1800 kg / m 3, compressive strength 10MPa, softening coefficient 0.075, frost resistance strength loss 27%, drying shrinkage 0.08%, leaching toxicity meets the requirements of lead ≤ 2mg / L, cadmium ≤ 0.1mg / L, mercury ≤ 0.02mg / L, arsenic ≤ 0.5mg / L, nickel ≤ 0.5mg / L, copper ≤ 10mg / L, zinc ≤ 10mg / L, chromium ≤ 1.5mg / L.

[0098] Example 9

[0099] In this embodiment, a sludge autoclaved brick was prepared. The preparation method was the same as that in Example 1, except that the molding pressure was 10 MPa.

[0100] After characterization, it was found that the density of the product obtained in this embodiment was 1700 kg / m 3 , compressive strength 13MPa, softening coefficient 0.088, frost resistance strength loss 16%, drying shrinkage 0.06%, leaching toxicity meets the requirements of lead ≤ 2mg / L, cadmium ≤ 0.1mg / L, mercury ≤ 0.02mg / L, arsenic ≤ 0.5mg / L, nickel ≤ 0.5mg / L, copper ≤ 10mg / L, zinc ≤ 10mg / L, chromium ≤ 1.5mg / L.

[0101] Example 10

[0102] In this embodiment, a sludge autoclaved brick is prepared. The preparation method is the same as that in Example 1, except that the brick is directly autoclaved without static curing.

[0103] After characterization, it was found that the density of the product obtained in this embodiment was 1800 kg / m 3 , compressive strength 23MPa, softening coefficient 1.00, frost resistance strength loss 12%, drying shrinkage 0.03%, leaching toxicity meets the requirements of lead ≤ 2mg / L, cadmium ≤ 0.1mg / L, mercury ≤ 0.02mg / L, arsenic ≤ 0.5mg / L, nickel ≤ 0.5mg / L, copper ≤ 10mg / L, zinc ≤ 10mg / L, chromium ≤ 1.5mg / L. The product stability is poor, and 15% of the test blocks will crack.

[0104] Example 11

[0105] In this embodiment, a sludge autoclaved brick is prepared. The preparation method is the same as that in Example 1, except that the maximum autoclaving temperature is 220° C. and the pressure is 1.2 MPa.

[0106] After characterization, it was found that the density of the product obtained in this embodiment was 1800 kg / m 3, compressive strength 32MPa, softening coefficient 1.10, frost resistance strength loss 10%, drying shrinkage 0.03%, leaching toxicity meets the requirements of lead ≤ 2mg / L, cadmium ≤ 0.1mg / L, mercury ≤ 0.02mg / L, arsenic ≤ 0.5mg / L, nickel ≤ 0.5mg / L, copper ≤ 10mg / L, zinc ≤ 10mg / L, chromium ≤ 1.5mg / L.

[0107] Example 12

[0108] In this embodiment, a sludge autoclaved brick is prepared. The preparation method is the same as that in Example 1, except that the maximum autoclaving temperature is 160° C. and the pressure is 0.8 MPa.

[0109] After characterization, it was found that the density of the product obtained in this embodiment was 1800 kg / m 3 , compressive strength 24MPa, softening coefficient 1.00, frost resistance strength loss 10%, drying shrinkage 0.03%, leaching toxicity meets the requirements of lead ≤ 2mg / L, cadmium ≤ 0.1mg / L, mercury ≤ 0.02mg / L, arsenic ≤ 0.5mg / L, nickel ≤ 0.5mg / L, copper ≤ 10mg / L, zinc ≤ 10mg / L, chromium ≤ 1.5mg / L.

[0110] The following conclusions can be drawn from the results of the above examples:

[0111] It can be seen from the comparison of Examples 1-4 that the more sludge is added, the lower the compressive strength, softening coefficient, and frost resistance of the product will be;

[0112] Comparison between Example 1, Example 3 and Example 4 shows that when the sludge content is 55 parts, the compressive strength can reach 35 MPa, which is much higher than that of ordinary concrete bricks.

[0113] Comparison between Example 1 and Example 7 shows that increasing the alkali excitation dosage will improve the performance of the product, but adding too much will reduce the economic efficiency;

[0114] Comparison between Example 1 and Example 8 shows that when the sludge particles are not ground, the performance of the product is significantly reduced. This is because the effective silicon content in the raw materials is reduced, which reduces the hydrothermal reaction.

[0115] Comparison between Example 1 and Example 9 shows that when the molding pressure is reduced, the performance of the product is also reduced. This is because the reduction in molding pressure causes the internal voids of the product to be less dense.

[0116] Comparison between Example 1 and Example 10 shows that the stability of the product without static curing will be reduced. Curing under a certain temperature of 40±2°C and humidity of 60±5%RH can ensure that the product has higher stability.

[0117] Comparison between Example 1 and Example 11 shows that when the steaming pressure and temperature are increased, the product performance is improved, but the energy consumption is also increased.

[0118] It can be seen that the present invention (1) has a high solid waste utilization rate, and the solid waste content in the silt brick can reach more than 95%; (2) the reaction consumes less energy than sintered bricks and does not emit gases that have an impact on the environment; (3) has excellent mechanical properties and strong product stability.

[0119] The embodiment described above is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Persons skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent substitution or equivalent transformation falls within the scope of protection of the present invention.

Claims

1. A sludge autoclaved brick, characterized in that: Prepared by the following raw materials in parts by weight: 50-80 parts of silt, 5 parts of lime, 5-15 parts of blast furnace slag, 3 or 5 parts of alkali residue, 2 or 15 parts of stone powder, 10-20 parts of electric furnace slag, 2-5 parts of desulfurized gypsum, 1-5 parts of silica fume, 3 parts of fly ash, 3-8 parts of cement, 0.01-0.5 parts of polycarboxylate water reducer, 0.01-0.1 parts of alkali activator, and 8-12 parts of water; The preparation method of the silt autoclaved brick is as follows: S1: Pre-treating sludge, stone powder, fly ash, blast furnace slag, alkali residue and desulfurization gypsum; The sludge is dehydrated by filter pressing and naturally dried to reduce its moisture content to less than 20%; S2: 5 parts of lime, 10-20 parts of electric furnace slag, 1-5 parts of silica fume, 3-8 parts of cement, 0.01-0.5 parts of polycarboxylate water reducer, 0.01-0.1 parts of alkali activator, 8-12 parts of water, 2 or 15 parts of pretreated stone powder, 3 parts of fly ash, 2-5 parts of desulfurized gypsum, 50-80 parts of sludge, 5-15 parts of blast furnace slag and 3 or 5 parts of alkali residue are mixed and stirred to obtain a mixture; S3: placing the mixture into a mold and pressing it into shape using a static press; The pressure during pressing is controlled between 10 and 20 MPa; S4: placing the pressed bricks into an autoclave curing device for static curing; The static curing is to keep the bricks in an environment with a temperature of 30-50°C and a humidity of 50%RH-70%RH for 1-3 days; S5: placing the bricks after static curing in an autoclave and performing a hydrothermal reaction under high temperature and high pressure to obtain silt autoclaved bricks; The temperature of the hydrothermal reaction is 160~220°C, the pressure is 0.8~1.4MPa, and the time is 3~6 hours.

2. The sludge autoclaved brick according to claim 1, characterized in that: The particle size of the stone powder is less than 0.075 mm.

3. The sludge autoclaved brick according to claim 1, characterized in that: The particle size of the electric furnace slag is less than 4.75 mm.

4. The sludge autoclaved brick according to claim 1, characterized in that: In step S1, silt, stone powder, fly ash, blast furnace slag, alkali residue and desulfurization gypsum are pre-treated by ball milling to reduce the particle size to less than 0.075 mm.

5. The sludge autoclaved brick according to claim 1, characterized in that: In step S2, the polycarboxylate water reducer is uniformly mixed with water to obtain a mixed solution; stone powder, electric furnace slag, silica fume, fly ash, cement, alkali activator, lime, desulfurization gypsum, sludge, blast furnace slag and alkali residue are mixed and stirred for 5 to 15 minutes, and then the mixed solution is added, and the mixing and stirring is continued for 3 to 5 minutes at a stirring rate of more than 300 r / min to obtain a mixture.

6. The sludge autoclaved brick according to claim 1, characterized in that: In step S5, the bricks after static curing are placed in an autoclave, and the autoclave is heated stepwise to the hydrothermal reaction temperature, specifically as follows: gradually heating from room temperature to 50°C, with a heating time of 10 to 30 minutes; gradually heating from 50°C to 100°C, with a heating time of 30 to 120 minutes; gradually heating from 100°C to 150°C, with a heating time of 60 to 180 minutes; and gradually heating from 150°C to the hydrothermal reaction temperature, with a heating time of 30 to 90 minutes.