River channel sediment-based baking-free ceramic granule light aggregate and preparation method thereof

Abstract

The application provides a kind of based on river channel sediment's baking-free ceramic granule light aggregate and its preparation method, the preparation method includes: the pretreatment of sediment, the dry dredged sediment block is crushed, sieved, to obtain sediment;Ceramic granule light aggregate raw material, steel slag and fly ash are ground and sieved, the sieved steel slag, fly ash and the sediment of step are mixed to obtain dry material;Mix sodium silicate and lye to prepare alkali activator;Ceramic granule light aggregate preparation, dry material, metakaolin and foam stabilizer are mixed, spray alkali activator and hydrogen peroxide solution and granulation, to obtain ceramic precursor;The maintenance of ceramic granule light aggregate, ceramic precursor is steam cured.The preparation method provided by the application has low energy consumption, solves the problem of difficult treatment of dredged sediment to some extent, achieves waste utilization, and the produced ceramic better meets the requirements of light aggregate for building materials;It also has good removal effect on heavy metal cadmium in water.

Description

Technical Field

[0001] This invention belongs to the fields of river dredging industry and building materials technology, specifically relating to a non-fired ceramsite lightweight aggregate based on riverbed sediment and its preparation method. Background Technology

[0002] The silt beneath lakes is called river and lake sediment, a mixture of clay, sand, organic matter, and various minerals. It is formed through long-term physical, chemical, and biological processes, transforming and depositing the mixture at the bottom of the water. The accumulation of river sediment at the bottom not only raises the riverbed and affects river flow, but the pollutants (nitrogen and phosphorus compounds, organic matter, and heavy metals, etc.) within it can also cause secondary pollution to the overlying water bodies. As my country has achieved increasing success in controlling river and lake water pollution, polluted sediment, as a persistent source of pollution, has received considerable attention. Therefore, research has begun on the treatment and disposal of sediment, with sediment resource utilization being one of the main methods.

[0003] There are three main ways to utilize sediment resources: land application, energy recovery, and material utilization. Among these, using dredged sediment to replace clay in the preparation of building materials or environmentally functional materials is forward-looking. Material utilization solidifies harmful substances such as heavy metals within the sediment, not only solving the disposal problem of dredged sediment and reducing clay usage, but also allowing it to be used in construction or as filter media, turning waste into treasure and achieving sustainable development. Currently, the main process for preparing ceramsite from sediment, both domestically and internationally, is the sintering method. Many studies have achieved good results in preparing sintered ceramsite using sediment as raw material. However, calcining ceramsite consumes a large amount of energy and generates a large amount of waste gas and dust during the firing process. Utilizing a non-fired method to prepare sediment ceramsite is an effective way to utilize river and lake sediment resources. On the one hand, it reduces the consumption of mineral resources such as clay, solving the problem of by-products from river and lake dredging; on the other hand, it reduces energy consumption, which is more conducive to sustainable development. Meanwhile, there is currently a serious cadmium pollution problem in water. Therefore, it is essential to explore a feasible non-fired technology to prepare ceramsite that combines lightweight and environmentally friendly properties. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a non-fired ceramsite lightweight aggregate based on riverbed sediment and its preparation method. The sediment-based non-fired ceramsite lightweight aggregate prepared by the method of this invention conforms to the specifications of GB / T 17431-2010 "Lightweight Aggregates and Their Test Methods," overcoming the technical obstacle of loose and difficult-to-form ceramsite made from sediment. Furthermore, the prepared non-fired ceramsite exhibits excellent removal efficiency for the heavy metal cadmium in water. Moreover, the method of this invention reduces energy consumption while also lowering the possibility of secondary pollution.

[0005] In a first aspect, the present invention provides a method for preparing non-fired ceramsite lightweight aggregate based on riverbed sediment, comprising:

[0006] 1) Pretreatment of bottom sediment: The dried dredged bottom sediment blocks are crushed and sieved to obtain bottom sediment;

[0007] 2) Raw materials for ceramsite lightweight aggregate: Steel slag and fly ash are ground and sieved. The sieved steel slag, fly ash and bottom mud from step 1) are mixed to obtain dry material; water glass and alkali solution are mixed to prepare alkali activator.

[0008] 3) Preparation of ceramsite lightweight aggregate: Mix the dry material, metakaolin and foam stabilizer from step 2), spray with the alkali activator and hydrogen peroxide aqueous solution from step 2) and granulate to obtain ceramsite precursor;

[0009] 4) Curing of ceramsite lightweight aggregate: Steam curing of the ceramsite precursor from step 3).

[0010] Preferably, in step 1), the dried dredged sediment is ground using a ball mill at a speed of 700–900 r / min for 0.5–1.5 h; and / or, the sediment is passed through a 70–100 mesh, preferably 80 mesh, sieve; preferably, steel slag, fly ash, and metakaolin are passed through a 70–100 mesh, preferably 80 mesh, sieve. This invention uses the above-mentioned ball milling process to reduce energy consumption. Simultaneously, the dried sediment and other materials at the preferred mesh sizes are processed using steps 2)–4) of this invention and other raw materials in synergistic treatment to obtain high-quality ceramsite lightweight aggregate. The prepared ceramsite has excellent molding performance, and its performance indicators fully meet the standard requirements for lightweight aggregates used in building materials. Moreover, the prepared non-fired ceramsite exhibits excellent compressive strength and bulk density, and has a good removal effect on heavy metals, especially cadmium, achieving an unexpected improvement in technical performance.

[0011] Further preferably, the dredged sediment comes from East Lake in Wuhan, Hubei Province; the steel slag and fly ash come from solid waste produced by Baowu Steel Group in Wuhan, Hubei Province. The method for preparing the specific ceramsite lightweight aggregate provided by this invention is particularly effective for treating dredged sediment from East Lake in Wuhan, Hubei Province, and steel slag from Baowu Steel Group, and produces ceramsite lightweight aggregate of better quality than that prepared from other sediments and waste residues.

[0012] Further preferred, in step 2), based on the mass of the dry material as 100%, the composition is: bottom mud 51-70%, steel slag 5-12%, and fly ash 18-44%.

[0013] Further preferably, in step 2), the alkaline solution is a 12-15 mol / L NaOH solution, preferably 14 mol / L; and / or, the modulus of the water glass is 3.27; the mass ratio of the alkaline solution to the water glass is 1.4-1.6, preferably 1.5.

[0014] Further preferably, in step 3), the concentration of the hydrogen peroxide aqueous solution is 20-40%, preferably 30%. The inventors have also discovered that the alkaline activator prepared according to this invention, together with the specific dry materials, metakaolin, and foam stabilizer system of this invention, interact to give the non-fired ceramsite better mechanical properties and improve its surface and internal pore structure, resulting in better removal of heavy metals, especially cadmium, from wastewater by the prepared ceramsite lightweight aggregate.

[0015] Further preferably, the amount of hydrogen peroxide aqueous solution added is 3-7% of the total mass of the dry material, preferably 5%; the weight ratio of the alkaline activator to the hydrogen peroxide aqueous solution is 6-16:1, preferably 9.3:1. In this invention, using the preferred ratio of hydrogen peroxide aqueous solution results in a high rate of decrease in bulk density, leading to lightweight ceramsite with a slightly reduced strength but a more significant decrease in density, exhibiting high cadmium removal rate and better overall performance. This invention also found that further using the preferred weight ratio of alkaline activator to hydrogen peroxide aqueous solution yields even better results.

[0016] Further preferably, in step 3), the amount of the high-purity terephthalic acid added is 5% of the dry material; and / or, the amount of the foam stabilizer added is 1‰ to 5‰, preferably 2‰, of the total mass of the hydrogen peroxide aqueous solution and the dry material. Compared with other dosages, the overall effect of the ceramsite prepared by using the preferred dosages of high-purity terephthalic acid and foam stabilizer can be further improved in this invention.

[0017] Further preferred, in step 3), the tilt angle of the granulator disc is 42-47°, preferably 45°, and the rotation speed of the granulator is 45-55 rpm, preferably 50 rpm.

[0018] Further optimization, in step 4), steam curing is performed at 70-90℃, preferably 80℃; the curing time is 20-30h, preferably 24h.

[0019] Secondly, the non-fired ceramsite lightweight aggregate based on riverbed sediment provided by the present invention is prepared by the aforementioned method for preparing non-fired ceramsite lightweight aggregate based on riverbed sediment; preferably, the non-fired ceramsite lightweight aggregate meets the specifications of GB / T 17431-2010 "Lightweight Aggregates and Their Test Methods", with a compressive strength of 2.72-6.14 MPa and a bulk density of 603.6-832 kg / m³. 3 The removal rate of cadmium was 89.65%–95.15%.

[0020] In this invention, by employing a specific mixing design and optimizing the proportions of various materials, the overall performance of the prepared non-fired ceramsite lightweight aggregate can be unexpectedly and significantly improved under preferred conditions. This results in an aggregate that possesses both high compressive strength and lower bulk density, while also achieving a high removal rate of cadmium from water. Most preferably, the aggregate prepared in this embodiment has a compressive strength of 5.22 MPa and a bulk density of 665.8 kg / m³. 3 The removal rate of cadmium was 95.46%.

[0021] The beneficial effects of this invention are at least as follows: riverbed sediment, steel slag, and fly ash all contain some mineral components similar to clay, such as Al2O3 and SiO2, which can replace clay in the manufacture of building materials such as cement, ceramsite, and bricks. This invention uses these three waste materials as raw materials to prepare ceramsite, reducing the consumption of clay resources and achieving the goal of resource utilization of solid waste. In particular, this invention, through process and mixing design, controls the proportions and parameters of each material. By granulating dry materials, metakaolin, foam stabilizer, alkali activator, and hydrogen peroxide aqueous solution to obtain ceramsite precursors, and then steam curing the ceramsite precursors, the effects of each material are maximized. This results in the production of non-fired ceramsite lightweight aggregate that better meets the specifications of GB / T17431-2010 "Lightweight Aggregates and Their Test Methods," overcoming the technical obstacle of loose and difficult-to-form ceramsite made from sediment. Simultaneously, the prepared non-fired ceramsite exhibits excellent removal effects on heavy metals (such as cadmium and lead) in wastewater, especially showing a high removal rate for cadmium in water. This non-fired ceramsite lightweight aggregate has excellent application prospects. Furthermore, the alkali activation method used in this invention to prepare non-fired ceramsite lightweight aggregate from sediment can reduce energy consumption while lowering the possibility of secondary pollution. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] Unless otherwise specified, the raw materials used in this invention are all conventionally available products on the market; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0024] The sediment used in this invention is sediment from East Lake in Wuhan. This sediment mainly contains heavy metals, inorganic nutrients primarily composed of nitrogen and phosphorus, and recalcitrant organic matter. Fly ash and steel slag are both solid waste from the production of Wuhan Baowu Steel Group. Water glass is ordinary industrial water glass, commonly known as sodium silicate, and its performance meets the technical requirements of GB4209-96 "Industrial Sodium Silicate". The foam stabilizer was purchased from Shandong Ruiyuan Building Materials Chemical Co., Ltd. The test method for the removal rate of cadmium in water in this invention is as follows: 1 g / L of ceramsite lightweight aggregate is added to a 50 mg / L cadmium nitrate solution, and the solution is kept at a constant temperature and shaken at 25℃ and 150 r / min for 24 h. Subsequently, the concentration of cadmium in the solution is determined using an atomic absorption spectrometer. Cadmium removal rate = (Cadmium concentration in solution before adsorption - Cadmium concentration in solution after adsorption) / Cadmium concentration in solution before adsorption × 100%.

[0025] In the following embodiments of the present invention, the composition and content of bottom mud, steel slag and fly ash are shown in the table below.

[0026] Table 1. Composition and content of bottom mud, steel slag, and fly ash

[0027]

[0028] Example 1

[0029] This embodiment provides a method for preparing ceramsite lightweight aggregate using riverbed sediment as the main material. The steps are as follows:

[0030] 1. Pretreatment of dredged sediment: After the dredged sediment is dehydrated and dried, it is crushed in a ball mill at a speed of 800 r / min for 1 hour. The dredged sediment is then passed through an 80-mesh sieve to obtain dredged sediment powder.

[0031] 2. Raw materials for ceramsite lightweight aggregate: Steel slag and fly ash are ground separately and passed through an 80-mesh sieve. Then, they are mixed evenly in a ratio of 59.2% bottom mud, 5% steel slag and 35.8% fly ash to obtain the dry material for preparing ceramsite lightweight aggregate; water glass (modulus 3.27) and 14 mol / L sodium hydroxide solution are mixed evenly to prepare an alkali activator;

[0032] 3. Preparation of lightweight expanded clay aggregate: Mix the above dry materials, 5% metakaolin, and 2‰ foam stabilizer evenly, then pour the mixture into a granulator with a disc tilt angle of 45° and a rotation speed of 50 rpm. Then, evenly spray an alkali activator and 30% hydrogen peroxide (the weight ratio of the two sprayed is 9.3:1, and the 30% hydrogen peroxide is 5% of the total dry material mass) for granulation.

[0033] 4. Curing of ceramsite lightweight aggregate: After granulation, the aggregate is placed in a container and steam-cured in an 80℃ oven for 24 hours.

[0034] After testing, the ceramsite lightweight aggregate obtained in this embodiment fully meets the standard requirements of GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods", with a compressive strength of 5.22 MPa and a bulk density of 665.8 kg / m³. 3 The removal rate of cadmium was 95.46%.

[0035] Example 2

[0036] This embodiment provides a method for preparing ceramsite lightweight aggregate using riverbed sediment as the main material. The steps are as follows:

[0037] 1. Pretreatment of dredged sediment: After the dredged sediment is dehydrated and dried, it is crushed in a ball mill at a speed of 800 r / min for 1 hour. The dredged sediment is then passed through an 80-mesh sieve to obtain dredged sediment powder.

[0038] 2. Raw materials for ceramsite lightweight aggregate: Steel slag and fly ash are ground separately and passed through an 80-mesh sieve. Then, they are mixed evenly in a ratio of 51% bottom mud, 9.6% steel slag and 39.4% fly ash to obtain the dry material for preparing ceramsite lightweight aggregate; water glass (modulus 3.27) and 14 mol / L sodium hydroxide solution are mixed evenly to prepare an alkali activator;

[0039] 3. Preparation of lightweight expanded clay aggregate: Mix the above dry materials, 5% metakaolin, and 2‰ foam stabilizer evenly, then pour the mixture into a granulator with a disc tilt angle of 45° and a rotation speed of 50 rpm. Then, evenly spray an alkali activator and 30% hydrogen peroxide (the weight ratio of the two sprayed is 9.3:1, and the 30% hydrogen peroxide is 5% of the total dry material mass) for granulation.

[0040] 4. Curing of ceramsite lightweight aggregate: After granulation, the aggregate is placed in a container and steam-cured in an 80℃ oven for 24 hours.

[0041] After testing, the ceramsite lightweight aggregate obtained in this embodiment fully meets the standard requirements of GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods", with a compressive strength of 3.03 MPa and a bulk density of 746.7 kg / m³. 3 The removal rate of cadmium was 91.37%.

[0042] Example 3

[0043] This embodiment provides a method for preparing ceramsite lightweight aggregate using riverbed sediment as the main material. The steps are as follows:

[0044] 1. Pretreatment of dredged sediment: After the dredged sediment is dehydrated and dried, it is crushed in a ball mill at a speed of 800 r / min for 1 hour. The dredged sediment is then passed through an 80-mesh sieve to obtain dredged sediment powder.

[0045] 2. Raw materials for ceramsite lightweight aggregate: Steel slag and fly ash are ground separately and passed through an 80-mesh sieve. Then, they are mixed evenly in a ratio of 51% bottom mud, 10% steel slag and 39% fly ash to obtain the dry material for preparing ceramsite lightweight aggregate; water glass (modulus 3.27) and 14 mol / L sodium hydroxide solution are mixed evenly to prepare an alkali activator.

[0046] 3. Preparation of lightweight expanded clay aggregate: Mix the above dry materials, 5% metakaolin, and 2‰ foam stabilizer evenly, then pour the mixture into a granulator with a disc tilt angle of 45° and a rotation speed of 50 rpm. Then, evenly spray an alkali activator and 30% hydrogen peroxide (the weight ratio of the two sprayed is 9.3:1, and the 30% hydrogen peroxide is 5% of the total dry material mass) for granulation.

[0047] 4. Curing of ceramsite lightweight aggregate: After granulation, the aggregate is placed in a container and steam-cured in an 80℃ oven for 24 hours.

[0048] After testing, the ceramsite lightweight aggregate obtained in this embodiment fully meets the standard requirements of GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods", with a compressive strength of 2.81 MPa and a bulk density of 785.2 kg / m³. 3 The removal rate of cadmium was 93.24%.

[0049] Example 4

[0050] This embodiment provides a method for preparing ceramsite lightweight aggregate using riverbed sediment as the main material. The steps are as follows:

[0051] 1. Pretreatment of dredged sediment: After the dredged sediment is dehydrated and dried, it is crushed in a ball mill at a speed of 800 r / min for 1 hour. The dredged sediment is then passed through an 80-mesh sieve to obtain dredged sediment powder.

[0052] 2. Raw materials for ceramsite lightweight aggregate: Steel slag and fly ash are ground separately and passed through an 80-mesh sieve. Then, they are mixed evenly in a ratio of 70% bottom mud, 10.2% steel slag and 19.8% fly ash to obtain the dry material for preparing ceramsite lightweight aggregate; water glass (modulus 3.27) and 14 mol / L sodium hydroxide solution are mixed evenly to prepare an alkali activator;

[0053] 3. Preparation of lightweight expanded clay aggregate: Mix the above dry materials, 5% metakaolin, and 2‰ foam stabilizer evenly, then pour the mixture into a granulator with a disc tilt angle of 45° and a rotation speed of 50 rpm. Then, evenly spray an alkali activator and 30% hydrogen peroxide (the weight ratio of the two sprayed is 9.3:1, and the 30% hydrogen peroxide is 5% of the total dry material mass) for granulation.

[0054] 4. Curing of ceramsite lightweight aggregate: After granulation, the aggregate is placed in a container and steam-cured in an 80℃ oven for 24 hours.

[0055] After testing, the ceramsite lightweight aggregate obtained in this embodiment fully meets the standard requirements of GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods", with a compressive strength of 2.72 MPa and a bulk density of 732.5 kg / m³. 3 The removal rate of cadmium was 89.65%.

[0056] Example 5

[0057] This embodiment provides a method for preparing ceramsite lightweight aggregate using riverbed sediment as the main material. The steps are as follows:

[0058] 1. Pretreatment of dredged sediment: After the dredged sediment is dehydrated and dried, it is crushed in a ball mill at a speed of 800 r / min for 1 hour. The dredged sediment is then passed through an 80-mesh sieve to obtain dredged sediment powder.

[0059] 2. Raw materials for ceramsite lightweight aggregate: Steel slag and fly ash are ground separately and passed through an 80-mesh sieve. Then, they are mixed evenly in a ratio of 65.6% bottom mud, 12% steel slag and 22.4% fly ash to obtain the dry material for preparing ceramsite lightweight aggregate; water glass (modulus 3.27) and 14 mol / L sodium hydroxide solution are mixed evenly to prepare an alkali activator;

[0060] 3. Preparation of lightweight expanded clay aggregate: Mix the above dry materials, 5% metakaolin, and 2‰ foam stabilizer evenly, then pour the mixture into a granulator with a disc tilt angle of 45° and a rotation speed of 50 rpm. Then, evenly spray an alkali activator and 30% hydrogen peroxide (the weight ratio of the two sprayed is 9.3:1, and the 30% hydrogen peroxide is 5% of the total dry material mass) for granulation.

[0061] 4. Curing of ceramsite lightweight aggregate: After granulation, the aggregate is placed in a container and steam-cured in an 80℃ oven for 24 hours.

[0062] After testing, the ceramsite lightweight aggregate obtained in this embodiment fully meets the standard requirements of GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods", with a compressive strength of 3.07 MPa and a bulk density of 703.2 kg / m³. 3 The removal rate of cadmium was 90.32%.

[0063] Example 6

[0064] This embodiment provides a method for preparing ceramsite lightweight aggregate using riverbed sediment as the main material. The steps are as follows:

[0065] 1. Pretreatment of dredged sediment: After the dredged sediment is dehydrated and dried, it is crushed in a ball mill at a speed of 800 r / min for 1 hour. The dredged sediment is then passed through an 80-mesh sieve to obtain dredged sediment powder.

[0066] 2. Raw materials for ceramsite lightweight aggregate: Steel slag and fly ash are ground separately and passed through an 80-mesh sieve. Then, they are mixed evenly in a ratio of 59.2% bottom mud, 5% steel slag and 35.8% fly ash to obtain the dry material for preparing ceramsite lightweight aggregate; water glass (modulus 3.27) and 14 mol / L sodium hydroxide solution are mixed evenly to prepare an alkali activator;

[0067] 3. Preparation of lightweight expanded clay aggregate: Mix the above dry materials, 5% metakaolin, and 2‰ foam stabilizer evenly, then pour the mixture into a granulator with a disc tilt angle of 45° and a rotation speed of 50 rpm. Then, uniformly spray an alkali activator and 30% hydrogen peroxide (the weight ratio of the two sprayed is 15.5:1, and the 30% hydrogen peroxide is 3% of the total dry material mass) for granulation.

[0068] 4. Curing of ceramsite lightweight aggregate: After granulation, the aggregate is placed in a container and steam-cured in an 80℃ oven for 24 hours.

[0069] After testing, the ceramsite lightweight aggregate obtained in this embodiment fully meets the standard requirements of GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods", with a compressive strength of 6.14 MPa and a bulk density of 803.9 kg / m³. 3 The removal rate of cadmium was 92.93%.

[0070] Example 7

[0071] This embodiment provides a method for preparing ceramsite lightweight aggregate using riverbed sediment as the main material. The steps are as follows:

[0072] 1. Pretreatment of dredged sediment: After the dredged sediment is dehydrated and dried, it is crushed in a ball mill at a speed of 800 r / min for 1 hour. The dredged sediment is then passed through an 80-mesh sieve to obtain dredged sediment powder.

[0073] 2. Raw materials for ceramsite lightweight aggregate: Steel slag and fly ash are ground separately and passed through an 80-mesh sieve. Then, they are mixed evenly in a ratio of 59.2% bottom mud, 5% steel slag and 35.8% fly ash to obtain the dry material for preparing ceramsite lightweight aggregate; water glass (modulus 3.27) and 14 mol / L sodium hydroxide solution are mixed evenly to prepare an alkali activator;

[0074] 3. Preparation of lightweight expanded clay aggregate: Mix the above dry materials, 5% metakaolin, and 2‰ foam stabilizer evenly, then pour the mixture into a granulator with a disc tilt angle of 45° and a rotation speed of 50 rpm. Then, uniformly spray an alkali activator and 30% hydrogen peroxide (the weight ratio of the two sprayed is 11.6:1, and the 30% hydrogen peroxide is 4% of the total dry material mass) for granulation.

[0075] 4. Curing of ceramsite lightweight aggregate: After granulation, the aggregate is placed in a container and steam-cured in an 80℃ oven for 24 hours.

[0076] After testing, the ceramsite lightweight aggregate obtained in this embodiment fully meets the standard requirements of GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods", with a compressive strength of 5.82 MPa and a bulk density of 767.1 kg / m³. 3 The removal rate of cadmium was 93.86%.

[0077] Example 8

[0078] This embodiment provides a method for preparing ceramsite lightweight aggregate using riverbed sediment as the main material. The steps are as follows:

[0079] 1. Pretreatment of dredged sediment: After the dredged sediment is dehydrated and dried, it is crushed in a ball mill at a speed of 800 r / min for 1 hour. The dredged sediment is then passed through an 80-mesh sieve to obtain dredged sediment powder.

[0080] 2. Raw materials for ceramsite lightweight aggregate: Steel slag and fly ash are ground separately and passed through an 80-mesh sieve. Then, they are mixed evenly in a ratio of 59.2% bottom mud, 5% steel slag and 35.8% fly ash to obtain the dry material for preparing ceramsite lightweight aggregate; water glass (modulus 3.27) and 14 mol / L sodium hydroxide solution are mixed evenly to prepare an alkali activator;

[0081] 3. Preparation of lightweight expanded clay aggregate: Mix the above dry materials, 5% metakaolin, and 2‰ foam stabilizer evenly, then pour the mixture into a granulator with a disc tilt angle of 45° and a rotation speed of 50 rpm. Then, uniformly spray an alkali activator and 30% hydrogen peroxide (the weight ratio of the two sprayed is 6.6:1, and the 30% hydrogen peroxide accounts for 7% of the total dry material mass) for granulation.

[0082] 4. Curing of ceramsite lightweight aggregate: After granulation, the aggregate is placed in a container and steam-cured in an 80℃ oven for 24 hours.

[0083] After testing, the ceramsite lightweight aggregate obtained in this embodiment fully meets the standard requirements of GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods", with a compressive strength of 2.73 MPa and a bulk density of 603.6 kg / m³. 3The removal rate of cadmium was 94.32%.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing non-fired ceramsite lightweight aggregate based on riverbed sediment, characterized in that, include: 1) Pretreatment of bottom sediment: The dried dredged bottom sediment blocks are crushed and passed through a 70-100 mesh sieve to obtain bottom sediment; 2) Lightweight aggregate raw materials: Steel slag and fly ash are ground and sieved. The steel slag, fly ash and bottom mud from step 1) after passing through a 70-100 mesh sieve are mixed to obtain dry material. Water glass and alkaline solution are mixed, wherein the alkaline solution is a 12-15 mol / L NaOH solution to prepare an alkaline activator. 3) Preparation of ceramsite lightweight aggregate: The dry material, metakaolin, and foam stabilizer from step 2) are mixed, and the alkali activator and a 20-40% hydrogen peroxide aqueous solution from step 2) are sprayed on and granulated to obtain the ceramsite precursor; the weight ratio of the alkali activator to the hydrogen peroxide aqueous solution is 6-16:1; the amount of hydrogen peroxide aqueous solution added is 3-7% of the total mass of the dry material; the amount of metakaolin added is 5% of the dry material; the amount of foam stabilizer added is 1‰-5‰ of the total mass of the hydrogen peroxide aqueous solution and the dry material; the metakaolin is passed through a 70-100 mesh sieve; 4) Curing of ceramsite lightweight aggregate: Steam curing of the ceramsite precursor from step 3).

2. The method for preparing non-fired ceramsite lightweight aggregate based on riverbed sediment according to claim 1, characterized in that, In step 1), the dried dredged sediment is ground using a ball mill at a speed of 700-900 r / min for 0.5-1.5 h.

3. The method for preparing non-fired ceramsite lightweight aggregate based on riverbed sediment according to claim 1, characterized in that, The bottom mud, steel slag, fly ash, and metakaolin were passed through an 80-mesh sieve.

4. The method for preparing non-fired ceramsite lightweight aggregate based on riverbed sediment according to claim 1, characterized in that, In step 2), based on the mass of the dry material as 100%, the bottom mud is 51-70%, steel slag is 5-12%, and fly ash is 18-44%.

5. The method for preparing lightweight aggregate based on riverbed sediment ceramsite according to claim 1, characterized in that, In step 2), the alkaline solution is a 14 mol / L NaOH solution; the mass ratio of the alkaline solution to the water glass is 1.

5.

6. The method for preparing non-fired ceramsite lightweight aggregate based on riverbed sediment according to claim 1, characterized in that, In step 3), the concentration of the hydrogen peroxide aqueous solution is 30%.

7. The method for preparing non-fired ceramsite lightweight aggregate based on riverbed sediment according to any one of claims 1-6, characterized in that, The amount of hydrogen peroxide aqueous solution added is 5% of the total mass of the dry material.

8. The method for preparing non-fired ceramsite lightweight aggregate based on riverbed sediment according to any one of claims 1-6, characterized in that, The weight ratio of the alkaline activator to the aqueous hydrogen peroxide solution is 9.3:

1.

9. The method for preparing non-fired ceramsite lightweight aggregate based on riverbed sediment according to any one of claims 1-6, characterized in that, In step 3), the amount of foam stabilizer added is 2‰ of the total mass of the hydrogen peroxide aqueous solution and the dry material.

10. The method for preparing non-fired ceramsite lightweight aggregate based on riverbed sediment according to any one of claims 1-6, characterized in that, In step 3), the tilt angle of the granulator disc is 42-47°, and the rotation speed of the granulator is 45-55 rpm.

11. The method for preparing non-fired ceramsite lightweight aggregate based on riverbed sediment according to claim 10, characterized in that, In step 3), the tilt angle of the granulator disc is 45° and the rotation speed of the granulator is 50 rpm.

12. The method for preparing lightweight aggregate based on riverbed sediment ceramsite according to any one of claims 1-6, characterized in that, In step 4), steam curing is carried out at 70-90℃ for 20-30 hours.

13. The method for preparing lightweight aggregate based on riverbed sediment ceramsite according to claim 12, characterized in that, In step 4), steam curing is performed at 80℃ for 24 hours.

14. A non-fired ceramsite lightweight aggregate based on riverbed sediment, characterized in that, It is prepared by the method for preparing non-fired ceramsite lightweight aggregate based on riverbed sediment as described in any one of claims 1-13.

15. The non-fired ceramsite lightweight aggregate based on riverbed sediment according to claim 14, characterized in that, The compressive strength of the non-fired ceramsite lightweight aggregate is 2.73–6.14 MPa, and the bulk density is 603.6–832 kg / m³. 3 The removal rate of cadmium was 89.65%–95.15%.

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