Coal gasification slag non-burned haydite and preparation method thereof

Abstract

This invention belongs to the field of ceramsite preparation technology, and provides a non-fired ceramsite made from coal gasification slag and its preparation method. The raw materials for the non-fired ceramsite made from coal gasification slag are a matrix of non-fired ceramsite made from coal gasification slag, a binder, an alkali activator, a water-reducing agent, and water. The matrix of the non-fired ceramsite made from coal gasification slag is composed of the following components by mass percentage: 50-60% coal gasification slag, 15-30% fly ash, 5-15% river sand, and 15-20% cement; the amounts of binder and alkali activator are 7-10% and 0-3% of the mass of the matrix of non-fired ceramsite made from coal gasification slag, respectively. This invention utilizes the low apparent density and pozzolanic activity of coal gasification slag raw materials, aiming to prepare non-fired ceramsite with low bulk density, low water absorption, and high strength by adjusting the raw material ratio and the amount of alkali activator, without the need for pore-forming agents or surface treatment, while ensuring that the coal gasification slag content is ≥50% and the cement content is ≤20%.

Description

Technical Field

[0001] This invention belongs to the field of ceramsite preparation technology, specifically relating to a non-fired ceramsite for coal gasification slag and its preparation method. Background Technology

[0002] The solid residue formed during coal gasification is called coal gasification slag. my country generates over 30 million tons of coal gasification slag annually, primarily through stockpiling and landfilling. How to achieve large-scale disposal of coal gasification slag and realize sustainable development is a pressing issue for the coal gasification industry. Ceramsite is a common large-scale resource utilization method for silicate solid waste and has high added value. Compared to sintered ceramsite, non-fired ceramsite has significant advantages such as low energy consumption, controllable performance, and continuous strength growth. However, due to the high density of silicate solid waste and the large number of capillary structures generated by water evaporation, non-fired ceramics generally suffer from high bulk density, high water absorption, and low strength, limiting the engineering application of non-fired ceramsite.

[0003] The advantage of using coal gasification slag as raw material to prepare non-fired ceramsite is that, due to the presence of a certain amount of residual carbon, the apparent density of coal gasification slag is lower than that of most other types of silicate solid waste, which is conducive to reducing the bulk density. However, excessive residual carbon will hinder cement hydration. Coal gasification slag has a certain pozzolanic activity, which is beneficial to improving the strength of non-fired ceramsite under alkali activation.

[0004] Invention patent CN111548111A discloses a method for preparing non-fired ceramsite from solid waste using sludge ash, coal gangue, industrial by-product gypsum, and coal gasification slag as main raw materials. This method has advantages such as short curing time (2-10 hours of natural curing followed by 4-10 hours of high-temperature curing), low water absorption (≤5%), and high compressive strength (≥12MPa), but also a high bulk density (≥1000kg / m³). 3 The content of coal gasification slag is low (10-50%). Invention patent CN114890A discloses a method for preparing high-strength ceramsite by self-sintering of fine coal gasification slag, with 100% coal gasification slag, a sintering temperature of 950-1050℃, and a bulk density ≤800kg / m³. 3The invention patent CN102372496A discloses a method for preparing ceramsite using gasification slag, with the amount of gasification slag being 80-95% and the sintering temperature being 900-1300℃. Invention patent CN107720358A discloses a method for preparing non-fired ceramsite using slag micro-powder mixed with perlite tailings. Perlite is used to reduce the bulk density, and water glass with a modulus of 1.0-1.2 is used as an activator. No cement is added. After standard curing for 7 days and surface coating with water glass of modulus 2.2, the water absorption rate is ≤5% and the compressive strength is ≥6MPa. Invention patent CN109665805A discloses a core-shell structure solidified sludge non-fired ceramsite and its preparation method. Through core material spheroidization, shell material coating, and heating curing processes, the resulting 500-grade ceramsite has a compressive strength ≥1.5MPa and a water absorption rate ≤7%.

[0005] The above-disclosed method for preparing non-fired ceramsite from coal gasification slag has the following problems: (1) The technology for preparing sintered ceramsite with high content of coal gasification slag is relatively mature, but the content of non-fired ceramsite prepared is less than 50%, which is not conducive to the large-scale utilization of coal gasification slag; (2) The method of adding low-density raw materials and foaming agents is generally used to reduce the bulk density of non-fired ceramsite, but the selection range of low-density raw materials is narrow and the addition of foaming agents has a great impact on the strength of non-fired ceramsite; (3) The water absorption rate of non-fired ceramsite is generally reduced by designing core-shell structure, surface treatment and other methods, which are relatively complicated processes. Summary of the Invention

[0006] The purpose of this invention is to provide a non-fired ceramsite made from coal gasification slag and its preparation method. Utilizing the characteristics of low apparent density and pozzolanic activity of coal gasification slag raw materials, and ensuring that the coal gasification slag content is ≥50% and the cement content is ≤20%, the invention aims to prepare non-fired ceramsite with low bulk density, low water absorption, and high strength by adjusting the raw material ratio and the amount of alkali activator, without adding pore-forming agents or surface treatment.

[0007] One objective of this invention is to provide a non-fired ceramsite made from coal gasification slag. This non-fired ceramsite is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 50-60% coal gasification slag, 15-30% fly ash, 5-15% river sand, and 15-20% cement. The binder is used at 7-10% of the mass of the non-fired ceramsite matrix, and the alkali activator is used at 0-3% of the mass of the non-fired ceramsite matrix. The mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.02-0.05:0.2-0.3.

[0008] Preferably, the fly ash contains 40-60 wt% SiO2, 20-30 wt% Al2O3, 0-10 wt% Fe2O3, 0-5 wt% CaO, 0-5 wt% MgO, and 0-10 wt% loss on ignition.

[0009] Preferably, the coal gasification slag contains 40-50 wt% SiO2, 15-25 wt% Al2O3, 10-20 wt% Fe2O3, 5-15 wt% CaO, 0-5 wt% MgO, and 10-25 wt% loss on ignition.

[0010] Preferably, the binder is one or both of water glass and pulp waste liquid.

[0011] Preferably, the water glass is sodium silicate or potassium silicate with a modulus of 2-4.

[0012] Preferably, the alkali activator is gypsum dihydrate.

[0013] Preferably, the cement is ordinary Portland cement with a strength grade of P·O 42.5 or higher.

[0014] Preferably, the water-reducing agent is a polycarboxylate water-reducing agent, and the solid content of the polycarboxylate high-efficiency water-reducing agent is greater than 40%.

[0015] The second objective of this invention is to provide a method for preparing the above-mentioned non-fired ceramsite from coal gasification slag, comprising the following steps:

[0016] After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh each raw material according to the proportion of non-fired ceramsite from the coal gasification slag.

[0017] After mixing coal gasification slag, fly ash, river sand, cement, binder and alkali activator evenly, a powder is obtained. Then, polycarboxylate superplasticizer and water are added, and after mixing evenly, granulation is carried out to obtain ceramsite raw meal. After steam curing, the ceramsite raw meal is taken out and naturally cured to obtain coal gasification slag non-fired ceramsite.

[0018] Preferably, the granulation speed is 45-70 r / min, the tilt angle is 40-50°, the steam curing temperature is 70-90℃, the humidity is 85-95%, and the time is 12-24h; the natural curing temperature is 15-25℃, the humidity is 85-95%, and the time is 7d.

[0019] Compared with the prior art, the advantages of this invention are as follows:

[0020] 1. This invention utilizes the low apparent density and pozzolanic activity of coal gasification slag as raw material. It aims to ensure that the coal gasification slag content is ≥50% and the cement content is ≤20%. By adjusting the proportions of coal gasification slag, cement, river sand, binder, and alkali activator, and the amount of alkali activator, the components of the non-fired ceramsite made from coal gasification slag are used in synergistic effects to promote the pozzolanic reaction between the coal gasification slag and fly ash. This increases the bulk density, reduces the 1-hour water absorption rate, increases the cylinder compressive strength, increases hydration products, enhances internal bonding strength, and improves the various properties of the non-fired ceramsite made from coal gasification slag. No pore-forming agent or surface treatment is required to prepare non-fired ceramsite with low bulk density, low water absorption, and high strength, achieving large-scale resource utilization of coal gasification slag. The bulk density, 1-hour water absorption rate, and cylinder compressive strength of the prepared non-fired ceramsite made from coal gasification slag all meet the national standard GB / T17431-2010 for 800-grade artificial lightweight aggregate, with a bulk density range of 760-785 kg / m³. 3 The water absorption rate is 8.9-9.9% in 1 hour, and the compressive strength of the cylinder is 6.1-7.2 MPa.

[0021] 2. The coal gasification slag and fly ash used in this invention are both bulk industrial solid wastes, widely available and easy to obtain, and have low cement content, so the raw material cost is low. The amount of coal gasification coarse slag used is 50-60%, and the bulk density of non-fired ceramsite can be reduced without the addition of pore-forming agents, thus realizing the large-scale resource utilization of coal gasification slag. Attached Figure Description

[0022] Figure 1 This is a process flow diagram for the non-fired ceramsite process of coal gasification slag in this invention;

[0023] Figure 2 The images show the XRD patterns of the non-fired ceramsite from coal gasification slag in Examples 1-3 of this invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0026] A type of non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 50-60% coal gasification slag, 15-30% fly ash, 5-15% river sand, and 15-20% cement. The binder is used at 7-10% of the mass of the non-fired ceramsite matrix, and the alkali activator is used at 0-3% of the mass of the non-fired ceramsite matrix. The mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.02-0.05:0.2-0.3.

[0027] This invention utilizes the low apparent density and pozzolanic activity of coal gasification slag as raw material. It aims to produce low-bulk-density, low-water-absorption, and high-strength non-fired ceramsite by adjusting the raw material ratio and the amount of alkali activator, while ensuring a coal gasification slag content of ≥50% and a cement content of ≤20%. This is achieved without the need for pore-forming agents or surface treatment. The bulk density, 1-hour water absorption, and cylinder compressive strength of the coal gasification slag non-fired ceramsite all meet the national standard GB / T17431-2010 for 800-grade artificial lightweight aggregates, with a bulk density range of 760-785 kg / m³. 3 The water absorption rate is 8.9-9.9% in 1 hour, and the compressive strength of the cylinder is 6.1-7.2 MPa.

[0028] In one specific embodiment, the fly ash contains 40-60 wt% SiO2, 20-30 wt% Al2O3, 0-10 wt% Fe2O3, 0-5 wt% CaO, 0-5 wt% MgO, and 0-10 wt% loss on ignition.

[0029] In one specific embodiment, the coal gasification slag contains 40-50 wt% SiO2, 15-25 wt% Al2O3, 10-20 wt% Fe2O3, 5-15 wt% CaO, 0-5 wt% MgO, and 10-25 wt% loss on ignition.

[0030] The coal gasification slag and fly ash used in this invention are both bulk industrial solid wastes, widely available and easily obtained, and have low cement content, thus resulting in low raw material costs. The amount of coarse coal gasification slag used is 50-60%, and the bulk density of non-fired ceramsite can be reduced without the addition of pore-forming agents, thereby realizing the large-scale resource utilization of coal gasification slag.

[0031] In one specific embodiment, the binder is one or both of water glass and pulp waste liquid.

[0032] In one specific embodiment, the alkali activator is gypsum dihydrate. The alkali activator gypsum dihydrate used in this invention can promote the pozzolanic reaction between coal gasification slag and fly ash, but excessive gypsum dihydrate will lead to internal volume expansion, increased interconnected voids, and even efflorescence.

[0033] In one specific embodiment, the water glass is sodium silicate or potassium silicate with a modulus of 2-4.

[0034] In one specific embodiment, the cement is ordinary Portland cement with a strength grade of P·O 42.5 or higher.

[0035] In one specific embodiment, the water-reducing agent is a polycarboxylate water-reducing agent, and the solid content of the polycarboxylate high-efficiency water-reducing agent is greater than 40%.

[0036] The preparation method of non-fired ceramsite from coal gasification slag includes the following steps:

[0037] After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh each raw material according to the proportion of non-fired ceramsite from the coal gasification slag.

[0038] After mixing coal gasification slag, fly ash, river sand, cement, binder and alkali activator evenly, a powder is obtained. Then, polycarboxylate superplasticizer and water are added, and after mixing evenly, granulation is carried out to obtain ceramsite raw meal. After steam curing, the ceramsite raw meal is taken out and naturally cured to obtain coal gasification slag non-fired ceramsite.

[0039] In one specific embodiment, the granulation speed is 45-70 r / min, the tilt angle is 40-50°, the steam curing temperature is 70-90℃, the humidity is 85-95%, and the time is 12-24h; the natural curing temperature is 15-25℃, the humidity is 85-95%, and the time is 7d.

[0040] The coal gasification slag and fly ash used in this invention are both bulk industrial solid wastes, widely available and easily obtained, and have low cement content, thus resulting in low raw material costs. The amount of coarse coal gasification slag used is 50-60%, and the bulk density of non-fired ceramsite can be reduced without the addition of pore-forming agents, thereby realizing the large-scale resource utilization of coal gasification slag.

[0041] The following specific examples will provide further details.

[0042] Example 1

[0043] A type of non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 50% coal gasification slag, 25% fly ash, 10% river sand, and 15% P·O 42.5 cement; the amount of sodium silicate with a modulus of 3.2 is 7% of the mass of the non-fired ceramsite matrix, and the amount of gypsum dihydrate is 3% of the mass of the non-fired ceramsite matrix; the mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.03:0.26; and the solid content of the polycarboxylate water-reducing agent is 40%.

[0044] The coal gasification slag contains 41.9 wt% SiO2, 15.5 wt% Al2O3, 17.7 wt% Fe2O3, 12.6 wt% CaO, 1.7 wt% MgO, and a loss on ignition of 22.5 wt%. The fly ash contains 54.0 wt% SiO2, 31.1 wt% Al2O3, 4.2 wt% Fe2O3, 4.0 wt% CaO, 1.2 wt% MgO, and a loss on ignition of 2.3%.

[0045] The above-mentioned method for preparing non-fired ceramsite from coal gasification slag is as follows: Figure 1 As shown, it includes the following steps:

[0046] S1. After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh various raw materials according to the proportion of coal gasification slag non-fired ceramsite.

[0047] S2. After mixing coal gasification slag, fly ash, river sand, P·O 42.5 cement, sodium silicate with a modulus of 3.2 and gypsum dihydrate evenly, a powder is obtained. Then, polycarboxylate superplasticizer and water are added and mixed evenly. The mixture is then fed into a disc granulator in small batches multiple times for granulation. The granulation speed is 70 r / min and the tilt angle is 50° to obtain ceramsite raw meal.

[0048] S3. The raw ceramsite is first steam-cured at a temperature of 70℃ and a humidity of 90±5% for 12 hours. Then it is taken out and naturally cured at a temperature of 20±5℃ and a humidity of 90±5% for 7 days to obtain non-fired ceramsite from coal gasification slag.

[0049] Example 2

[0050] A type of non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 55% coal gasification slag, 20% fly ash, 10% river sand, and 15% P·O 42.5 cement; the amount of sodium silicate with a modulus of 3.2 is 7% of the mass of the non-fired ceramsite matrix, and the amount of gypsum dihydrate is 3% of the mass of the non-fired ceramsite matrix; the mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.03:0.26; and the solid content of the polycarboxylate water-reducing agent is 40%.

[0051] The coal gasification slag contains 41.9 wt% SiO2, 15.5 wt% Al2O3, 17.7 wt% Fe2O3, 12.6 wt% CaO, 1.7 wt% MgO, and a loss on ignition of 22.5 wt%. The fly ash contains 54.0 wt% SiO2, 31.1 wt% Al2O3, 4.2 wt% Fe2O3, 4.0 wt% CaO, 1.2 wt% MgO, and a loss on ignition of 2.3 wt%.

[0052] The above-mentioned method for preparing non-fired ceramsite from coal gasification slag is as follows: Figure 1 As shown, it includes the following steps:

[0053] S1. After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh various raw materials according to the proportion of coal gasification slag non-fired ceramsite.

[0054] S2. After mixing coal gasification slag, fly ash, river sand, P·O 42.5 cement, sodium silicate with a modulus of 3.2 and gypsum dihydrate evenly, a powder is obtained. Then, polycarboxylate superplasticizer is added and mixed evenly. The powder is then fed into a disc granulator in small batches multiple times for granulation. The granulation speed is 70 r / min and the tilt angle is 50° to obtain ceramsite raw meal.

[0055] S3. The raw ceramsite is first steam-cured at a temperature of 70℃ and a humidity of 90±5% for 12 hours. Then it is taken out and naturally cured at a temperature of 20±5℃ and a humidity of 90±5% for 7 days to obtain non-fired ceramsite from coal gasification slag.

[0056] Example 3

[0057] A type of non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 60% coal gasification slag, 15% fly ash, 10% river sand, and 15% P·O 42.5 cement; 7% sodium silicate with a modulus of 3.2 and 3% gypsum dihydrate; the mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.03:0.26; and the solid content of the polycarboxylate water-reducing agent is 40%.

[0058] The coal gasification slag contains 41.9 wt% SiO2, 15.5 wt% Al2O3, 17.7 wt% Fe2O3, 12.6 wt% CaO, 1.7 wt% MgO, and a loss on ignition of 22.5 wt%. The fly ash contains 54.0 wt% SiO2, 31.1 wt% Al2O3, 4.2 wt% Fe2O3, 4.0 wt% CaO, 1.2 wt% MgO, and a loss on ignition of 2.3 wt%.

[0059] The above-mentioned method for preparing non-fired ceramsite from coal gasification slag is as follows: Figure 1 As shown, it includes the following steps:

[0060] S1. After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh various raw materials according to the proportion of coal gasification slag non-fired ceramsite.

[0061] S2. After mixing coal gasification slag, fly ash, river sand, P·O 42.5 cement, sodium silicate with a modulus of 3.2 and gypsum dihydrate evenly, a powder is obtained. Then, polycarboxylate superplasticizer is added and mixed evenly. The powder is then fed into a disc granulator in small batches multiple times for granulation. The granulation speed is 70 r / min and the tilt angle is 50° to obtain ceramsite raw meal.

[0062] S3. The raw ceramsite is first steam-cured at a temperature of 70℃ and a humidity of 90±5% for 12 hours. Then it is taken out and naturally cured at a temperature of 20±5℃ and a humidity of 90±5% for 7 days to obtain non-fired ceramsite from coal gasification slag.

[0063] Example 4

[0064] A type of non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 50% coal gasification slag, 25% fly ash, 5% river sand, and 20% P·O 42.5 cement; 5% sodium silicate with a modulus of 3.2, 5% pulp waste liquor, and 3% dihydrate gypsum; the mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.03:0.26; and the solid content of the polycarboxylate water-reducing agent is 40%.

[0065] The fly ash contained 41.9 wt% SiO2, 15.5 wt% Al2O3, 17.7 wt% Fe2O3, 12.6 wt% CaO, 1.7 wt% MgO, and a loss on ignition of 22.5 wt%. The coal gasification slag contained 54.0 wt% SiO2, 31.1 wt% Al2O3, 4.2 wt% Fe2O3, 4.0 wt% CaO, 1.2 wt% MgO, and a loss on ignition of 2.3 wt%.

[0066] The above-mentioned method for preparing non-fired ceramsite from coal gasification slag is as follows: Figure 1 As shown, it includes the following steps:

[0067] S1. After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh various raw materials according to the proportion of coal gasification slag non-fired ceramsite.

[0068] S2. Coal gasification slag, fly ash, river sand, P·O 42.5 cement, sodium silicate with a modulus of 3.2, pulp waste liquor and dihydrate gypsum are mixed evenly to obtain powder. Then polycarboxylate superplasticizer is added and mixed evenly. The powder is then fed into a disc granulator in small batches multiple times for granulation. The granulation speed is 70 r / min and the tilt angle is 50° to obtain ceramsite raw meal.

[0069] S3. The raw ceramsite is first steam-cured at a temperature of 70℃ and a humidity of 90±5% for 12 hours. Then it is taken out and naturally cured at a temperature of 20±5℃ and a humidity of 90±5% for 7 days to obtain non-fired ceramsite from coal gasification slag.

[0070] Example 5

[0071] A type of non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 50% coal gasification slag, 30% fly ash, 5% river sand, and 15% P·O 42.5 cement; the amount of sodium silicate with a modulus of 3.2 is 7% of the mass of the non-fired ceramsite matrix, and the amount of gypsum dihydrate is 2% of the mass of the non-fired ceramsite matrix; the mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.03:0.26; and the solid content of the polycarboxylate water-reducing agent is 40%.

[0072] The fly ash contained 41.9 wt% SiO2, 15.5 wt% Al2O3, 17.7 wt% Fe2O3, 12.6 wt% CaO, 1.7 wt% MgO, and a loss on ignition of 22.5 wt%. The coal gasification slag contained 54.0 wt% SiO2, 31.1 wt% Al2O3, 4.2 wt% Fe2O3, 4.0 wt% CaO, 1.2 wt% MgO, and a loss on ignition of 2.3 wt%.

[0073] The above-mentioned method for preparing non-fired ceramsite from coal gasification slag is as follows: Figure 1 As shown, it includes the following steps:

[0074] S1. After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh various raw materials according to the proportion of coal gasification slag non-fired ceramsite.

[0075] S2. After mixing coal gasification slag, fly ash, river sand, P·O 42.5 cement, sodium silicate with a modulus of 3.2 and gypsum dihydrate evenly, a powder is obtained. Then, polycarboxylate superplasticizer is added and mixed evenly. The powder is then fed into a disc granulator in small batches multiple times for granulation. The granulation speed is 70 r / min and the tilt angle is 50° to obtain ceramsite raw meal.

[0076] S3. The raw ceramsite is first steam-cured at a temperature of 70℃ and a humidity of 90±5% for 12 hours. Then it is taken out and naturally cured at a temperature of 20±5℃ and a humidity of 90±5% for 7 days to obtain non-fired ceramsite from coal gasification slag.

[0077] Example 6

[0078] A type of non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 50% coal gasification slag, 20% fly ash, 15% river sand, and 15% P·O 42.5 cement; 7% sodium silicate with a modulus of 3.2 and 2% gypsum dihydrate; the mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.03:0.26; and the solid content of the polycarboxylate water-reducing agent is 40%.

[0079] The fly ash contained 41.9 wt% SiO2, 15.5 wt% Al2O3, 17.7 wt% Fe2O3, 12.6 wt% CaO, 1.7 wt% MgO, and a loss on ignition of 22.5 wt%. The coal gasification slag contained 54.0 wt% SiO2, 31.1 wt% Al2O3, 4.2 wt% Fe2O3, 4.0 wt% CaO, 1.2 wt% MgO, and a loss on ignition of 2.3 wt%.

[0080] The above-mentioned method for preparing non-fired ceramsite from coal gasification slag is as follows: Figure 1 As shown, it includes the following steps:

[0081] S1. After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh various raw materials according to the proportion of coal gasification slag non-fired ceramsite.

[0082] S2. After mixing coal gasification slag, fly ash, river sand, P·O 42.5 cement, sodium silicate with a modulus of 3.2 and gypsum dihydrate evenly, a powder is obtained. Then, polycarboxylate superplasticizer is added and mixed evenly. The powder is then fed into a disc granulator in small batches multiple times for granulation. The granulation speed is 70 r / min and the tilt angle is 50° to obtain ceramsite raw meal.

[0083] S3. The raw ceramsite is first steam-cured at a temperature of 70℃ and a humidity of 90±5% for 12 hours. Then it is taken out and naturally cured at a temperature of 20±5℃ and a humidity of 90±5% for 7 days to obtain non-fired ceramsite from coal gasification slag.

[0084] Example 7

[0085] A type of non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 50% coal gasification slag, 25% fly ash, 10% river sand, and 15% P·O 42.5 cement; 5% sodium silicate with a modulus of 3.2, 5% pulp waste liquor, and 3% dihydrate gypsum; the mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.03:0.26; and the solid content of the polycarboxylate water-reducing agent is 40%.

[0086] The fly ash contained 41.9 wt% SiO2, 15.5 wt% Al2O3, 17.7 wt% Fe2O3, 12.6 wt% CaO, 1.7 wt% MgO, and a loss on ignition of 22.5 wt%. The coal gasification slag contained 54.0 wt% SiO2, 31.1 wt% Al2O3, 4.2 wt% Fe2O3, 4.0 wt% CaO, 1.2 wt% MgO, and a loss on ignition of 2.3 wt%.

[0087] The above-mentioned method for preparing non-fired ceramsite from coal gasification slag is as follows: Figure 1 As shown, it includes the following steps:

[0088] S1. After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh various raw materials according to the proportion of coal gasification slag non-fired ceramsite.

[0089] S2. Coal gasification slag, fly ash, river sand, P·O 42.5 cement, sodium silicate with a modulus of 3.2, pulp waste liquor and dihydrate gypsum are mixed evenly to obtain powder. Then polycarboxylate superplasticizer is added and mixed evenly. The powder is then fed into a disc granulator in small batches multiple times for granulation. The granulation speed is 70 r / min and the tilt angle is 50° to obtain ceramsite raw meal.

[0090] S3. The raw ceramsite is first steam-cured at a temperature of 70℃ and a humidity of 90±5% for 12 hours. Then it is taken out and naturally cured at a temperature of 20±5℃ and a humidity of 90±5% for 7 days to obtain non-fired ceramsite from coal gasification slag.

[0091] Example 8

[0092] A type of non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 50% coal gasification slag, 25% fly ash, 10% river sand, and 15% P·O 42.5 cement; the amount of sodium silicate with a modulus of 3.2 is 7% of the mass of the non-fired ceramsite matrix, and the amount of gypsum dihydrate is 3% of the mass of the non-fired ceramsite matrix; the mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.03:0.26; and the solid content of the polycarboxylate water-reducing agent is 40%.

[0093] The coal gasification slag contains 41.9 wt% SiO2, 15.5 wt% Al2O3, 17.7 wt% Fe2O3, 12.6 wt% CaO, 1.7 wt% MgO, and a loss on ignition of 22.5 wt%. The fly ash contains 54.0 wt% SiO2, 31.1 wt% Al2O3, 4.2 wt% Fe2O3, 4.0 wt% CaO, 1.2 wt% MgO, and a loss on ignition of 2.3 wt%.

[0094] The above-mentioned method for preparing non-fired ceramsite from coal gasification slag is as follows: Figure 1 As shown, it includes the following steps:

[0095] S1. After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh various raw materials according to the proportion of coal gasification slag non-fired ceramsite.

[0096] S2. After mixing coal gasification slag, fly ash, river sand, P·O 42.5 cement, sodium silicate with a modulus of 3.2 and gypsum dihydrate evenly, a powder is obtained. Then, polycarboxylate superplasticizer is added and mixed evenly. The powder is then fed into a disc granulator in small batches multiple times for granulation. The granulation speed is 70 r / min and the tilt angle is 50° to obtain ceramsite raw meal.

[0097] S3. The raw ceramsite is first steam-cured at a temperature of 90℃ and a humidity of 90±5% for 24 hours. Then it is taken out and naturally cured at a temperature of 20±5℃ and a humidity of 90±5% for 7 days to obtain non-fired ceramsite from coal gasification slag.

[0098] Comparative Example 1

[0099] A type of non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 65% coal gasification slag, 10% fly ash, 10% river sand, and 15% P·O 42.5 cement; 7% sodium silicate with a modulus of 3.2 and 3% gypsum dihydrate; the mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.03:0.26; and the solid content of the polycarboxylate water-reducing agent is 40%.

[0100] The coal gasification slag contains 41.9 wt% SiO2, 15.5 wt% Al2O3, 17.7 wt% Fe2O3, 12.6 wt% CaO, 1.7 wt% MgO, and a loss on ignition of 22.5 wt%. The fly ash contains 54.0 wt% SiO2, 31.1 wt% Al2O3, 4.2 wt% Fe2O3, 4.0 wt% CaO, 1.2 wt% MgO, and a loss on ignition of 2.3 wt%.

[0101] The above-mentioned method for preparing non-fired ceramsite from coal gasification slag is as follows: Figure 1 As shown, it includes the following steps:

[0102] S1. After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh various raw materials according to the proportion of coal gasification slag non-fired ceramsite.

[0103] S2. After mixing coal gasification slag, fly ash, river sand, P·O 42.5 cement, sodium silicate with a modulus of 3.2 and gypsum dihydrate evenly, a powder is obtained. Then, polycarboxylate superplasticizer is added and mixed evenly. The powder is then fed into a disc granulator in small batches multiple times for granulation. The granulation speed is 70 r / min and the tilt angle is 50° to obtain ceramsite raw meal.

[0104] S3. The raw ceramsite is first steam-cured at a temperature of 70℃ and a humidity of 90±5% for 12 hours. Then it is taken out and naturally cured at a temperature of 20±5℃ and a humidity of 90±5% for 7 days to obtain non-fired ceramsite from coal gasification slag.

[0105] Comparative Example 2

[0106] A type of non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 50% coal gasification slag, 30% fly ash, 10% river sand, and 10% P·O 42.5 cement; the amount of sodium silicate with a modulus of 3.2 is 7% of the mass of the non-fired ceramsite matrix, and the amount of gypsum dihydrate is 3% of the mass of the non-fired ceramsite matrix; the mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.03:0.26; and the solid content of the polycarboxylate water-reducing agent is 40%.

[0107] The coal gasification slag contains 41.9 wt% SiO2, 15.5 wt% Al2O3, 17.7 wt% Fe2O3, 12.6 wt% CaO, 1.7 wt% MgO, and a loss on ignition of 22.5 wt%. The fly ash contains 54.0 wt% SiO2, 31.1 wt% Al2O3, 4.2 wt% Fe2O3, 4.0 wt% CaO, 1.2 wt% MgO, and a loss on ignition of 2.3 wt%.

[0108] The above-mentioned method for preparing non-fired ceramsite from coal gasification slag is as follows: Figure 1 As shown, it includes the following steps:

[0109] S1. After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh various raw materials according to the proportion of coal gasification slag non-fired ceramsite.

[0110] S2. After mixing coal gasification slag, fly ash, river sand, P·O 42.5 cement, sodium silicate with a modulus of 3.2 and gypsum dihydrate evenly, a powder is obtained. Then, polycarboxylate superplasticizer is added and mixed evenly. The powder is then fed into a disc granulator in small batches multiple times for granulation. The granulation speed is 70 r / min and the tilt angle is 50° to obtain ceramsite raw meal.

[0111] S3. The raw ceramsite is first steam-cured at a temperature of 70℃ and a humidity of 90±5% for 12 hours. Then it is taken out and naturally cured at a temperature of 20±5℃ and a humidity of 90±5% for 7 days to obtain non-fired ceramsite from coal gasification slag.

[0112] Comparative Example 3

[0113] A type of non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 50% coal gasification slag, 25% fly ash, 10% river sand, and 15% P·O 42.5 cement; the amount of sodium silicate with a modulus of 3.2 is 11% of the mass of the non-fired ceramsite matrix; the mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.03:0.26; and the solid content of the polycarboxylate water-reducing agent is 40%.

[0114] The coal gasification slag contains 41.9 wt% SiO2, 15.5 wt% Al2O3, 17.7 wt% Fe2O3, 12.6 wt% CaO, 1.7 wt% MgO, and a loss on ignition of 22.5 wt%. The fly ash contains 54.0 wt% SiO2, 31.1 wt% Al2O3, 4.2 wt% Fe2O3, 4.0 wt% CaO, 1.2 wt% MgO, and a loss on ignition of 2.3 wt%.

[0115] The above-mentioned method for preparing non-fired ceramsite from coal gasification slag is as follows: Figure 1 As shown, it includes the following steps:

[0116] S1. After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh various raw materials according to the proportion of coal gasification slag non-fired ceramsite.

[0117] S2. After mixing coal gasification slag, fly ash, river sand, P·O 42.5 cement, sodium silicate with a modulus of 3.2 and gypsum dihydrate evenly, a powder is obtained. Then, polycarboxylate superplasticizer is added and mixed evenly. The powder is then fed into a disc granulator in small batches multiple times for granulation. The granulation speed is 70 r / min and the tilt angle is 50° to obtain ceramsite raw meal.

[0118] S3. The raw ceramsite is first steam-cured at a temperature of 70℃ and a humidity of 90±5% for 12 hours. Then it is taken out and naturally cured at a temperature of 20±5℃ and a humidity of 90±5% for 7 days to obtain non-fired ceramsite from coal gasification slag.

[0119] Comparative Example 4

[0120] A type of non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 50% coal gasification slag, 25% fly ash, 10% river sand, and 15% P·O 42.5 cement; the amount of sodium silicate with a modulus of 3.2 is 7% of the mass of the non-fired ceramsite matrix; the mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.03:0.26; and the solid content of the polycarboxylate water-reducing agent is 40%.

[0121] The coal gasification slag contains 41.9 wt% SiO2, 15.5 wt% Al2O3, 17.7 wt% Fe2O3, 12.6 wt% CaO, 1.7 wt% MgO, and a loss on ignition of 22.5 wt%. The fly ash contains 54.0 wt% SiO2, 31.1 wt% Al2O3, 4.2 wt% Fe2O3, 4.0 wt% CaO, 1.2 wt% MgO, and a loss on ignition of 2.3 wt%.

[0122] The above-mentioned method for preparing non-fired ceramsite from coal gasification slag is as follows: Figure 1 As shown, it includes the following steps:

[0123] S1. After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh various raw materials according to the proportion of coal gasification slag non-fired ceramsite.

[0124] S2. After mixing coal gasification slag, fly ash, river sand, P·O 42.5 cement and sodium water glass with a modulus of 3.2 evenly, a powder is obtained. Then, polycarboxylate superplasticizer is added and mixed evenly. The powder is then fed into a disc granulator in small batches multiple times for granulation. The granulation speed is 70 r / min and the tilt angle is 50° to obtain ceramsite raw meal.

[0125] S3. The raw ceramsite is first steam-cured at a temperature of 70℃ and a humidity of 90±5% for 12 hours. Then it is taken out and naturally cured at a temperature of 20±5℃ and a humidity of 90±5% for 7 days to obtain non-fired ceramsite from coal gasification slag.

[0126] Comparative Example 5

[0127] A type of non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 50% coal gasification slag, 25% fly ash, 10% river sand, and 15% P·O 42.5 cement; the amount of sodium silicate with a modulus of 3.2 is 7% of the mass of the non-fired ceramsite matrix, and the amount of gypsum dihydrate is 5% of the mass of the non-fired ceramsite matrix; the mass ratio of the non-fired ceramsite matrix, water-reducing agent, and water is 1:0.03:0.26; and the solid content of the polycarboxylate water-reducing agent is 40%.

[0128] The coal gasification slag contains 41.9 wt% SiO2, 15.5 wt% Al2O3, 17.7 wt% Fe2O3, 12.6 wt% CaO, 1.7 wt% MgO, and a loss on ignition of 22.5 wt%. The fly ash contains 54.0 wt% SiO2, 31.1 wt% Al2O3, 4.2 wt% Fe2O3, 4.0 wt% CaO, 1.2 wt% MgO, and a loss on ignition of 2.3 wt%.

[0129] The above-mentioned method for preparing non-fired ceramsite from coal gasification slag is as follows: Figure 1 As shown, it includes the following steps:

[0130] S1. After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh various raw materials according to the proportion of coal gasification slag non-fired ceramsite.

[0131] S2. After mixing coal gasification slag, fly ash, river sand, P·O 42.5 cement, sodium silicate with a modulus of 3.2 and gypsum dihydrate evenly, a powder is obtained. Then, polycarboxylate superplasticizer is added and mixed evenly. The powder is then fed into a disc granulator in small batches multiple times for granulation. The granulation speed is 70 r / min and the tilt angle is 50° to obtain ceramsite raw meal.

[0132] S3. The raw ceramsite is first steam-cured at a temperature of 70℃ and a humidity of 90±5% for 12 hours. Then it is taken out and naturally cured at a temperature of 20±5℃ and a humidity of 90±5% for 7 days to obtain non-fired ceramsite from coal gasification slag.

[0133] The performance of the expanded clay aggregates in Examples 1-8 and Comparative Examples 1-5 was tested using the test methods for bulk density, compressive strength and water absorption rate in GB / T 17431.2-2010. The results are shown in Table 1.

[0134] Table 1. Performance of Ceramsite in Examples and Comparative Examples

[0135] Example 1 775.3 9.3 6.8 Example 2 770.4 9.5 6.5 Example 3 765.2 9.9 6.1 Example 4 762.5 8.9 7.2 Example 5 760.8 9.1 6.8 Example 6 785.5 9.6 6.9 Example 7 773.4 9.0 7.0 Example 8 771.4 9.0 7.0 Comparative Example 1 750.6 12.1 5.0 Comparative Example 2 730.1 14.7 4.5 Comparative Example 3 690.4 14.9 4.3 Comparative Example 4 787.6 10.7 4.5 Comparative Example 5 767.6 13.7 4.7

[0136] As shown in Table 1, the bulk density, 1-hour water absorption rate, and cylinder compressive strength of the non-fired ceramsite from coal gasification slag in Examples 1-8 all meet the national standard GB / T17431-2010 for 800-grade artificial lightweight aggregates, with a bulk density range of 760-785 kg / m³. 3 The 1-hour water absorption rate is 8.9-9.9%, and the cylinder compressive strength is 6.1-7.2 MPa. Examples 1-3 show that increasing the amount of gasification slag can reduce the bulk density, but it also increases the 1-hour water absorption rate and reduces the cylinder compressive strength. Comparative Example 1 shows that when the amount of gasification slag is 65%, the various properties of the gasification slag-free ceramsite do not meet the standards. This is partly because the density of gasification slag is lower than that of other silicate solid wastes, increasing the difficulty of molding at higher dosages; and partly because a large amount of residual carbon severely hinders the hydration process of the gasification slag-free ceramsite. Therefore, the suitable addition range for gasification slag is 50-60%. Examples 1 and 4 show that increasing the amount of cement can increase hydration products and enhance internal bonding strength, which is a beneficial measure to improve the various properties of gasification slag-free ceramsite. Comparative Example 2 shows that when the cement addition is 10%, the various properties of the gasification slag-free ceramsite do not meet the standards. Considering that excessive cement addition does not conform to the basic national policy of energy conservation and carbon reduction, the suitable cement addition range is 15-20%. Examples 1, 5, and 6 show that increasing the amount of river sand significantly increases the bulk density and 1-hour water absorption rate, while the cylinder compressive strength remains relatively unchanged. Therefore, the suitable addition range for river sand is 5-15%. Examples 1 and 7 show that appropriately reducing the amount of water glass and using a binary binder of water glass and pulp waste liquor is beneficial for reducing the 1-hour water absorption rate and increasing the cylinder compressive strength, mainly due to the strong wetting and binding ability of pulp waste liquor and residual carbon. Combined with Comparative Example 3, it is evident that when water glass is added alone as a binder, excessive addition will lead to a sharp decline in the performance of the non-fired ceramsite of coal gasification slag. Water glass is both a binder and an alkali activator; appropriate addition can promote the pozzolanic reaction between coal gasification slag and fly ash, while excessive addition leads to internal volume expansion, increased interconnected voids, and even efflorescence. Therefore, the suitable addition amount of binder is 7-10%. Examples 1 and 8 show that increasing the curing temperature and extending the curing time is beneficial for improving the overall performance of non-fired ceramsite of coal gasification slag, but it will also increase costs and energy consumption. As can be seen from Examples 1, 4, and 5, the combined alkali activation effect of gypsum dihydrate and water glass is better than that of water glass alone. Excessive addition will cause volume expansion, similar to water glass. The appropriate addition amount is 2-3%.

[0137] Figure 2 The images show the XRD patterns of the non-fired ceramsite from coal gasification slag in Examples 1-3 of this invention. Figure 2As shown, the diffraction peaks of the quartz (SiO2) and calcite (CaCO3) crystal phases are relatively sharp. In addition, mullite (3Al2O3·2SiO2) and the hydration product ettringite (3CaO·Al2O3·3CaSO4·32H2O) are also present. Quartz, calcite, and mullite are the main mineral components of the gasification slag, and the diffraction peaks of all three increase with the increase of the gasification slag addition. With the increase of the gasification slag addition, the diffraction peak of ettringite first increases and then decreases, reaching its maximum value at a gasification slag addition of 55%. When the gasification slag addition increases from 50% to 55%, the increase in ettringite is attributed to the pozzolanic properties of the gasification slag; when it increases from 55% to 60%, the decrease in ettringite is mainly attributed to the hindering effect of residual carbon on the hydration process.

[0138] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0139] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A type of non-fired ceramsite for coal gasification slag, characterized in that, The non-fired ceramsite made from coal gasification slag is obtained by mixing and curing the following raw materials: a non-fired ceramsite matrix made from coal gasification slag, a binder, an alkali activator, a water-reducing agent, and water. The non-fired ceramsite matrix is ​​composed of the following components by mass percentage: 50-60% coal gasification slag, 15-30% fly ash, 5-15% river sand, and 15-20% cement. The amount of binder is 7-10% of the mass of the non-fired ceramsite matrix made from coal gasification slag, and the amount of alkali activator is 2-3% of the mass of the non-fired ceramsite matrix made from coal gasification slag. The mass ratio of the non-fired ceramsite matrix made from coal gasification slag, the water-reducing agent, and water is 1:0.02-0.05:0.2-0.

3. The binder is one or both of water glass and pulp waste liquid. The water glass is sodium silicate or potassium silicate with a modulus of 2-4. The alkali activator is gypsum dihydrate.

2. The non-fired ceramsite for coal gasification slag as described in claim 1, characterized in that, The fly ash contains 40-60 wt% SiO2, 20-30 wt% Al2O3, 0-10 wt% Fe2O3, 0-5 wt% CaO, 0-5 wt% MgO, and 0-10 wt% loss on ignition.

3. The non-fired ceramsite for coal gasification slag as described in claim 1, characterized in that, The coal gasification slag contains 40-50 wt% SiO2, 15-25 wt% Al2O3, 10-20 wt% Fe2O3, 5-15 wt% CaO, 0-5 wt% MgO, and 10-25 wt% loss on ignition.

4. The non-fired ceramsite for coal gasification slag as described in claim 1, characterized in that, The cement is ordinary Portland cement with a strength grade of P·O 42.5 or higher.

5. The non-fired ceramsite for coal gasification slag as described in claim 1, characterized in that, The water-reducing agent is a polycarboxylate water-reducing agent, and the solid content of the polycarboxylate high-efficiency water-reducing agent is greater than 40%.

6. A method for preparing non-fired ceramsite from coal gasification slag according to any one of claims 1-5, characterized in that, Includes the following steps: After crushing, drying and ball milling the coal gasification slag, pass it through a 60-mesh sieve and weigh each raw material according to the proportion of non-fired ceramsite from the coal gasification slag. After mixing coal gasification slag, fly ash, river sand, cement, binder and alkali activator evenly, a powder is obtained. Then, polycarboxylate superplasticizer and water are added, and after mixing evenly, granulation is carried out to obtain ceramsite raw meal. After steam curing, the ceramsite raw meal is taken out and naturally cured to obtain coal gasification slag non-fired ceramsite.

7. The method for preparing non-fired ceramsite from coal gasification slag according to claim 6, characterized in that, The granulation speed is 45-70 r / min, the tilt angle is 40-50°, the steam curing temperature is 70-90℃, the humidity is 85-95%, and the time is 12-24h; the natural curing temperature is 15-25℃, the humidity is 85-95%, and the time is 7d.

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