A kind of light and high-strength ceramsite prepared by using aluminum ash and preparation method thereof

Abstract

The invention provides a lightweight and high-strength ceramsite prepared by using aluminum ash and a preparation method thereof, belonging to the technical field of solid waste recycling. The invention discloses a method for preparing light high-strength ceramsite by using aluminum ash, comprising the following steps: mixing 60-86% of aluminum ash, 5-20% of gasified slag, 5-20% of ferrosilicon ash, 4-10% of bentonite and an external additive to obtain a mixed material; the mass of the external additive is 2-4% of the total mass of the aluminum ash, the gasified slag, the ferrosilicon ash and the bentonite; adding water to the mixed material, and then performing balling, aging and drying in sequence to obtain ceramsite to be fired; heating the ceramsite to be fired from room temperature to 200 DEG C within 1-2 hours, then heating from 200 DEG C to 500 DEG C within 1-2 hours, then heating from 500 DEG C to 800 DEG C within 2-3 hours, then heating from 800 DEG C to 1100 DEG C within 2-3 hours, and finally firing at a temperature of 1100-1240 DEG C to obtain light high-strength ceramsite.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste recycling, and particularly to a lightweight and high-strength ceramsite prepared from aluminum ash and a preparation method thereof. Background Art

[0002] Aluminum ash is a general term for the products obtained after the molten slag generated during the production of electrolytic aluminum, casting aluminum, and recycled aluminum is cooled. The aluminum ash generated during the production of recycled aluminum and aluminum processing, as well as the secondary aluminum ash generated during the aluminum recovery process, are classified as hazardous solid waste (HW48). With the continuous expansion of the production scale of the aluminum industry and the continuous increase in aluminum production, the generation amount of aluminum ash is also increasing. At present, most production enterprises only recycle the primary aluminum ash with a relatively high metal aluminum content. For the remaining aluminum slag, secondary aluminum ash, etc. after recycling, due to the relatively low metal aluminum content and the main form of aluminum being alumina, it is difficult to achieve a high recovery rate and economic benefits when continuing to recover metallic aluminum, and they are mostly piled up or landfilled in the form of waste slag, which not only causes waste of aluminum resources but also seriously pollutes the surrounding environment.

[0003] Currently, the resource utilization ways of secondary aluminum ash slag mainly include: extraction of metallic aluminum or Al 2 O 3 , synthesis of cryolite and magnesium aluminate spinel, castables, alumina-based ceramics, refractory bricks, concrete, etc. Secondary aluminum ash is generated from the waste after the aluminum smelting slag is ball-milled and secondarily processed to extract metallic aluminum. Its main components are 5-12% metallic aluminum and 60-80% alumina.

[0004] Ferrosilicon ash is an industrial waste residue formed by collecting and treating the dust escaping with the waste gas during the smelting of ferrosilicon alloy through a special trapping device. Ferrosilicon ash contains a large amount of amorphous silicon oxides. Currently, the use of ferrosilicon ash is mainly as additives for cement and refractory materials, binders for metallurgical pellets, dispersants for chemical products, fillers for rubber and plastics, plastic encapsulants for the electronics industry, and castings for the electrical engineering industry. However, these technologies cannot utilize ferrosilicon ash with high added value, so new methods need to be explored for the comprehensive utilization of ferrosilicon ash.

[0005] Gasification slag is a solid waste generated in the coal gasification process. It has a relatively high carbon content, good looseness, and a certain calorific value. Currently, the patent literature on the resource utilization of gasification slag mainly focuses on the field of secondary combustion.

[0006] Sintered and expanded ceramsite has the characteristics of light bulk density, high strength, low thermal conductivity, heat insulation, fire prevention, heat preservation and sound insulation. These excellent properties have gradually led to more and more applications of ceramsite in the field of high-rise building building materials. However, there are still many problems in the current ceramsite production process. Some formulas and methods have been disclosed in the patent literature in recent years, and the common problems include: a. Limited raw material sources and high production costs; b. Imperfect firing system and low emphasis on product yield; c. Quality indicators such as density, strength, and water absorption still need to be improved.

[0007] Therefore, providing a preparation process with wide raw material sources, low cost and excellent ceramsite properties has become an urgent technical problem to be solved in this field. Summary of the Invention

[0008] The purpose of the present invention is to provide a lightweight and high-strength ceramsite prepared from aluminum ash and its preparation method. The preparation method provided by the present invention is simple, has a high solid waste utilization rate, low cost, and the obtained lightweight and high-strength ceramsite has a smaller density, higher strength and lower water absorption.

[0009] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0010] The present invention provides a method for preparing lightweight and high-strength ceramsite from aluminum ash, comprising the following steps:

[0011] (1) Mix 60-86% of aluminum ash, 5-20% of gasification slag, 5-20% of ferrosilicon ash, 4-10% of bentonite and an external additive to obtain a mixed material;

[0012] The total mass percentage of the aluminum ash, gasification slag, ferrosilicon ash and bentonite is 100%; the mass of the external additive is 2-4% of the total mass of the aluminum ash, gasification slag, ferrosilicon ash and bentonite;

[0013] (2) Add water to the mixed material obtained in step (1), and then carry out balling, aging and drying in sequence to obtain the ceramsite to be fired;

[0014] (3) Heat the ceramsite to be fired obtained in step (2) from room temperature to 200 °C within 1-2 h, then heat it from 200 °C to 500 °C within 1-2 h, then heat it from 500 °C to 800 °C within 2-3 h, then heat it from 800 °C to 1100 °C within 2-3 h, and finally carry out firing at a temperature of 1100-1240 °C to obtain lightweight and high-strength ceramsite.

[0015] Preferably, in step (1), the particle sizes of the aluminum ash, gasification slag and ferrosilicon ash are independently ≥ 200 mesh.

[0016] Preferably, the external additive in step (1) is pulverized coal and / or silicon carbide.

[0017] Preferably, the aluminum ash, gasification slag and ferrosilicon ash in step (1) are dried before mixing, and the drying temperature is 85-105°C.

[0018] Preferably, the rotation speed of the pelletizer during pelletizing in step (2) is 18-36 r / min.

[0019] Preferably, the aging time in step (2) is 8-12 h.

[0020] Preferably, the drying temperature in step (2) is 85-105°C, and the drying time is 3-5 h.

[0021] Preferably, the particle size of the ceramsite to be fired in step (2) is 3-18 mm.

[0022] Preferably, the firing operation in step (3) is specifically as follows: first, the temperature is raised from 1100°C to 1140-1240°C within 1-2 h, and then the temperature is maintained at 1140-1240°C for 1-3 h.

[0023] The present invention provides a lightweight and high-strength ceramsite prepared by the method according to the above technical solution.

[0024] The present invention provides a method for preparing lightweight and high-strength ceramsite using aluminum ash, comprising the following steps: (1) Mixing 60-86% of aluminum ash, 5-20% of gasification slag, 5-20% of ferrosilicon ash, 4-10% of bentonite and an external additive to obtain a mixed material; the total mass percentage of the aluminum ash, gasification slag, ferrosilicon ash and bentonite is 100%; the mass of the external additive is 2-4% of the total mass of the aluminum ash, gasification slag, ferrosilicon ash and bentonite; (2) Adding water to the mixed material obtained in step (1), and then successively performing balling, aging and drying to obtain the ceramsite to be fired; (3) Heating the ceramsite to be fired obtained in step (2) from room temperature to 200°C within 1-2 h, then heating from 200°C to 500°C within 1-2 h, then heating from 500°C to 800°C within 2-3 h, then heating from 800°C to 1100°C within 2-3 h, and finally firing at a temperature of 1100-1240°C to obtain the lightweight and high-strength ceramsite. The present invention uses aluminum ash, gasification slag, ferrosilicon ash, bentonite and an external additive as raw materials. The aluminum ash mainly provides an aluminum source, the ferrosilicon ash mainly provides a silicon source, the gasification slag contains residual carbon and has a certain calorific value, which can save sintering energy to a certain extent and increase the content of closed pores inside the ceramsite. The bentonite mainly plays a binding role and has a certain micro-expansion characteristic, which can play a role in reducing the density; by controlling the dosages of the aluminum ash and ferrosilicon ash, the density of the ceramsite can be reduced while having good mechanical properties; through aging, the moisture in the material has sufficient time for autonomous and uniform diffusion, avoiding poor exhaust during the drying process in the next process and improving the finished product performance of the ceramsite; by heating between room temperature and 200°C for 1-2 h, the low-boiling solvents in the ceramsite to be fired can volatilize, by heating between 200-500°C for 1-2 h, the pulverized coal in the ceramsite decomposes and forms initial pores, by heating between 500-800°C for 2-3 h, the carbonates in the ceramsite decompose and foam, by heating between 800-1100°C for 2-3 h, a binding phase can be formed in the ceramsite, and by firing at a temperature of 1100-1240°C, a main crystal phase can be formed in the ceramsite. The results of the examples show that the apparent density of the lightweight and high-strength ceramsite prepared by the preparation method provided by the present invention is 1200-1500 kg / m 3 , the bulk density is 730-900 kg / m 3 , the water absorption rate < 8%, and the cylinder compressive strength > 18 MPa.

[0025] In the preparation method provided by the present invention, the utilization rate of solid waste is ≥ 90%, and various solid wastes are effectively formula-complemented and coupled to obtain lightweight and high-strength ceramsite with light weight, small density and excellent mechanical properties, far superior to the industry standard "GBT17431-2010 Lightweight Aggregates and Their Test Methods"; moreover, the preparation method provided by the present invention is simple and the design of the firing system is more accurate. Detailed implementation manners

[0026] The present invention provides a method for preparing lightweight and high-strength ceramsite using aluminum ash, comprising the following steps:

[0027] (1) Mix 60-86% of aluminum ash, 5-20% of gasification slag, 5-20% of ferrosilicon ash, 4-10% of bentonite and an external additive to obtain a mixed material;

[0028] The total mass percentage of the aluminum ash, gasification slag, ferrosilicon ash and bentonite is 100%; the mass of the external additive is 2-4% of the total mass of the aluminum ash, gasification slag, ferrosilicon ash and bentonite;

[0029] (2) Add water to the mixed material obtained in step (1), and then carry out balling, aging and drying in sequence to obtain the ceramsite to be fired;

[0030] (3) Heat the ceramsite to be fired obtained in step (2) from room temperature to 200 °C within 1-2 h, then heat it from 200 °C to 500 °C within 1-2 h, then heat it from 500 °C to 800 °C within 2-3 h, then heat it from 800 °C to 1100 °C within 2-3 h, and finally carry out firing at a temperature of 1100-1240 °C to obtain the lightweight and high-strength ceramsite.

[0031] The present invention mixes 60-86% of aluminum ash, 5-20% of gasification slag, 5-20% of ferrosilicon ash, 4-10% of bentonite and an external additive to obtain a mixed material.

[0032] In the present invention, the total mass percentage of the aluminum ash, gasification slag, ferrosilicon ash and bentonite is 100%. By mass percentage, the mixed material provided by the present invention contains 60-86% of aluminum ash, preferably 65-80%, and more preferably 70-75%. In the present invention, the aluminum ash mainly provides an aluminum source, but too much aluminum ash will increase the density of the ceramsite, and too little will not be able to form a high-strength crystal phase during the sintering of the ceramsite. Therefore, its content is controlled within the range of 60-86%.

[0033] By mass percentage, the mixed material provided by the present invention contains 5-20% of gasification slag, preferably 10-15%. In the present invention, the gasification slag contains residual carbon and has a certain calorific value, which can save the sintering energy to a certain extent and increase the content of closed pores inside the ceramsite.

[0034] By mass percentage, the mixed material provided by the present invention contains 5-20% of ferrosilicon ash, preferably 10-15%. In the present invention, the ferrosilicon ash mainly provides a silicon source, but too little ferrosilicon ash will cause difficulty in forming the ceramsite, and too much will make the strength of the ceramsite poor. Therefore, its content is controlled within the range of 5-20%.

[0035] By mass percentage, the mixed material provided by the present invention contains 4-10% of bentonite, preferably 5-8%, more preferably 6-7%. In the present invention, the bentonite mainly plays a binding role and has a certain micro-expansion characteristic that can play a role in reducing density.

[0036] In the present invention, the mass of the added auxiliary agent is 2-4% of the total mass of aluminum ash, gasification slag, ferrosilicon ash and bentonite, preferably 2.5-3.5%, more preferably 3-3.5%. In the present invention, the added auxiliary agent is preferably pulverized coal and / or silicon carbide; when the added auxiliary agent is pulverized coal and silicon carbide, the present invention has no special limitation on the dosage relationship between the pulverized coal and silicon carbide, and any dosage can be used. By adding the added auxiliary agent, on the one hand, the calorific value of the mixed material can be increased, thereby saving sintering energy and increasing the content of closed pores inside the product, and on the other hand, a silicon source can be provided, thereby regulating the silicon content.

[0037] The present invention has no special limitation on the specific sources of the aluminum ash, gasification slag, ferrosilicon ash, bentonite and added auxiliary agent, and commercially available products well-known to those skilled in the art can be used.

[0038] In the present invention, the particle sizes of the aluminum ash, gasification slag and ferrosilicon ash are preferably independently ≥200 mesh. In the present invention, when the particle sizes of the aluminum ash, gasification slag and ferrosilicon ash do not meet the above conditions, the present invention preferably performs ball milling treatment on the aluminum ash, gasification slag and ferrosilicon ash. The present invention has no special limitation on the specific operation of the ball milling treatment, which is determined according to the common technical knowledge of those skilled in the art, and it is only necessary that the screen residue of the aluminum ash, gasification slag and ferrosilicon ash passing through a 200-mesh sieve is less than 5%.

[0039] In the present invention, the aluminum ash, gasification slag and ferrosilicon ash are preferably dried before mixing; the temperature of the drying treatment is preferably 85-105°C. The present invention has no special limitation on the time of the drying treatment, which can be determined according to the common technical knowledge of those skilled in the art. Through the drying treatment, the present invention can remove the moisture in the aluminum ash, gasification slag and ferrosilicon ash.

[0040] The present invention has no special limitation on the specific manner of mixing, as long as the components can be mixed evenly.

[0041] After obtaining the mixed material, the present invention adds water to the mixed material, and then performs pelletizing, aging and drying in sequence to obtain the ceramic pellets to be fired.

[0042] The present invention has no special limitation on the dosage of the water, which is determined according to the common technical knowledge of those skilled in the art, and normal granulation can be achieved.

[0043] In the present invention, the rotation speed of the pelletizing machine during pelletizing is preferably 18 - 36 r / min. By controlling the rotation speed of the pelletizing machine, better pelletization can be achieved in the present invention, and the pelletization rate > 95%.

[0044] In the present invention, the aging time is preferably 8 - 12 h, more preferably 9 - 10 h. Through aging in the present invention, the moisture in the material has sufficient time for autonomous and uniform diffusion, avoiding poor exhaust during the drying process in the next process and improving the finished product performance of the ceramsite.

[0045] In the present invention, the drying temperature is preferably 85 - 105 °C; the drying time is preferably 3 - 5 h. In the present invention, the drying is preferably carried out in an electrothermal blast drying oven. There is no special limitation on the specific model of the electrothermal blast drying oven in the present invention, and commercially available products well-known to those skilled in the art can be used. By drying the pellets in the present invention, the moisture in the pellets can be removed, facilitating subsequent firing.

[0046] In the present invention, the particle size of the ceramsite to be fired is preferably 3 - 18 mm, more preferably 5 - 15 mm. By controlling the particle size of the ceramsite to be fired in the present invention, the particle size of the ceramsite can meet the requirements.

[0047] After obtaining the ceramsite to be fired, in the present invention, the ceramsite to be fired is first heated from room temperature to 200 °C within 1 - 2 h, then heated from 200 °C to 500 °C within 1 - 2 h, then heated from 500 °C to 800 °C within 2 - 3 h, then heated from 800 °C to 1100 °C within 2 - 3 h, and finally fired at a temperature of 1100 - 1240 °C to obtain lightweight and high-strength ceramsite. By heating for 1 - 2 h between room temperature and 200 °C in the present invention, the low-boiling solvents in the ceramsite to be fired can volatilize. By heating for 1 - 2 h between 200 - 500 °C, the pulverized coal in the ceramsite decomposes and initially forms pores. By heating for 2 - 3 h between 500 - 800 °C, the carbonate in the ceramsite decomposes and foams. By heating for 2 - 3 h between 800 - 1100 °C, a bonding phase can be formed in the ceramsite. By firing at a temperature of 1100 - 1240 °C, a main crystal phase can be formed in the ceramsite.

[0048] In the present invention, the specific operation of the firing is preferably: first, heat from 1100 °C to 1140 - 1240 °C within 1 - 2 h, and then keep the temperature at 1140 - 1240 °C for 1 - 3 h. Through the above process in the present invention, during the process of heating from 1100 °C to 1140 - 1240 °C, a main crystal phase can be formed in the ceramsite. During the process of keeping the temperature at 1140 - 1240 °C, the main crystal phase forms and further grows, thereby improving the mechanical properties of the ceramsite.

[0049] After the firing is completed, the present invention preferably cools the fired product in the furnace to room temperature to obtain lightweight and high-strength ceramsite.

[0050] The present invention uses aluminum ash, gasification slag, ferrosilicon ash, bentonite and an external additive as raw materials. The aluminum ash mainly provides an aluminum source, the ferrosilicon ash mainly provides a silicon source, the gasification slag contains residual carbon and has a certain calorific value, which can save sintering energy to a certain extent and increase the content of closed pores inside the ceramsite. The bentonite mainly plays a binding role and has a certain micro-expansion characteristic, which can play a role in reducing the density. By controlling the dosages of the aluminum ash and the ferrosilicon ash, the density of the ceramsite can be reduced while enabling it to have good mechanical properties. Through aging, the moisture in the materials has sufficient time for autonomous and uniform diffusion, avoiding poor exhaust during the drying process in the next process and improving the finished product performance of the ceramsite. By heating at a temperature between room temperature and 200°C for 1 - 2 hours, the low-boiling solvents in the green ceramsite can be volatilized. By heating at a temperature between 200 - 500°C for 1 - 2 hours, the pulverized coal in the ceramsite decomposes and initially forms through-holes. By heating at a temperature between 500 - 800°C for 2 - 3 hours, the carbonates in the ceramsite decompose and foam. By heating at a temperature between 800 - 1100°C for 2 - 3 hours, binding phases can be formed in the ceramsite. By firing at a temperature between 1100 - 1240°C, the main crystal phase can be formed in the ceramsite.

[0051] In the preparation method provided by the present invention, the proportion of solid waste utilization is ≥90%, and various solid wastes are effectively formulated and complementarily coupled to obtain lightweight and high-strength ceramsite with light weight, low density and excellent mechanical properties, far superior to the industry standard "GBT17431 - 2010 Lightweight Aggregates and Their Test Methods"; moreover, the preparation method provided by the present invention is simple and the design of the firing system is more accurate.

[0052] The present invention provides the lightweight and high-strength ceramsite prepared by the method according to the above technical solution. The lightweight and high-strength ceramsite provided by the present invention has a low density and high strength, far superior to the industry standard "GBT17431 - 2010 Lightweight Aggregates and Their Test Methods".

[0053] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art without making creative efforts based on the embodiments in the present invention belong to the scope of protection of the present invention.

[0054] Example 1

[0055] A method for preparing lightweight and high-strength ceramsite using aluminum ash, which consists of the following steps:

[0056] (1) First, dry the aluminum ash, gasification slag and ferrosilicon ash at 95 °C, and then mix 60% of aluminum ash, 17% of gasification slag, 15% of ferrosilicon ash, 8% of bentonite and an external additive by mass percentage to obtain a mixed material; the mass of the external additive is 3.6% of the total mass of aluminum ash, gasification slag, ferrosilicon ash and bentonite, and the external additive is 2.6% of pulverized coal and 1% of silicon carbide; the aluminum ash, gasification slag and ferrosilicon ash all pass through a 200-mesh sieve;

[0057] (2) Add water to the mixed material obtained in the step (1), and then carry out pelletizing, aging and drying in sequence to obtain the to-be-fired ceramsite; the rotation speed of the pelletizing machine during pelletizing is 28 r / min; the aging time is 8 h; the drying temperature is 100 °C, and the drying time is 3 h. The drying is carried out in an electrothermal blast drying oven; the particle size range of the to-be-fired ceramsite is 5 - 16 mm;

[0058] (3) First, heat the to-be-fired ceramsite obtained in the step (2) from room temperature to 200 °C within 2 h, then heat it from 200 °C to 500 °C within 2 h, then heat it from 500 °C to 800 °C within 2 h, then heat it from 800 °C to 1100 °C within 3 h, and continue to heat it from 1100 °C to 1180 °C within 2 h. Keep it at the temperature of 1180 °C for 2 h, and obtain lightweight and high-strength ceramsite after cooling with the furnace.

[0059] Test the performance of the lightweight and high-strength ceramsite prepared in Example 1 according to the industry standard "GBT17431 - 2010 Lightweight Aggregates and Their Test Methods", and the results are as follows: the apparent density is 1296 kg / m 3 , the bulk density is 735 kg / m 3 , the water absorption rate is 7.8%, and the cylinder compressive strength is 19.4 MPa.

[0060] Example 2

[0061] A method for preparing lightweight and high-strength ceramsite using aluminum ash, which consists of the following steps:

[0062] (1) First, dry the aluminum ash, gasification slag and ferrosilicon ash at 85 °C, and then mix 62% of aluminum ash, 20% of gasification slag, 8% of ferrosilicon ash, 10% of bentonite and an external additive by mass percentage to obtain a mixed material; the mass of the external additive is 4% of the total mass of aluminum ash, gasification slag, ferrosilicon ash and bentonite, and the external additive is 3% of pulverized coal and 1% of silicon carbide; the aluminum ash, gasification slag and ferrosilicon ash all pass through a 200-mesh sieve;

[0063] (2) Add water to the mixed material obtained in step (1), and then perform pelletizing, aging, and drying in sequence to obtain the ceramistite to be fired; the rotation speed of the pelletizer during pelletizing is 36 r / min; the aging time is 8 h; the drying temperature is 85 °C, and the drying time is 5 h. The drying is carried out in an electrothermal blast drying oven; the particle size range of the ceramistite to be fired is 3 - 12 mm;

[0064] (3) First, heat the ceramistite to be fired obtained in step (2) from room temperature to 200 °C within 1.5 h, then heat it from 200 °C to 500 °C within 1.5 h, then heat it from 500 °C to 800 °C within 3 h, then heat it from 800 °C to 1100 °C within 3 h, and continue to heat it from 1100 °C to 1180 °C within 1.5 h. Keep it at 1180 °C for 1.5 h, and obtain lightweight and high-strength ceramistite after cooling with the furnace.

[0065] Test the performance of the lightweight and high-strength ceramistite prepared in Example 2 according to the industry standard "GBT17431 - 2010 Lightweight Aggregates and Their Test Methods". The results are as follows: the apparent density is 1351 kg / m 3 , the bulk density is 786 kg / m 3 , the water absorption rate is 7.1%, and the cylinder compressive strength is 18.1 MPa.

[0066] Example 3

[0067] A method for preparing lightweight and high-strength ceramistite using aluminum ash consists of the following steps:

[0068] (1) First, dry the aluminum ash, gasification slag, and ferrosilicon ash at 100 °C, and then mix 66% of aluminum ash, 10% of gasification slag, 20% of ferrosilicon ash, 4% of bentonite, and an external additive by mass percentage to obtain a mixed material; the mass of the external additive is 3.5% of the total mass of aluminum ash, gasification slag, ferrosilicon ash, and bentonite. The external additive is 3% of pulverized coal and 0.5% of silicon carbide; the aluminum ash, gasification slag, and ferrosilicon ash all pass through a 200-mesh sieve;

[0069] (2) Add water to the mixed material obtained in step (1), and then perform pelletizing, aging, and drying in sequence to obtain the ceramistite to be fired; the rotation speed of the pelletizer during pelletizing is 25 r / min; the aging time is 10 h; the drying temperature is 100 °C, and the drying time is 4 h. The drying is carried out in an electrothermal blast drying oven; the particle size range of the ceramistite to be fired is 4 - 15 mm;

[0070] (3) The fired ceramsite obtained in step (2) is first heated from room temperature to 200°C within 1 h, then heated from 200°C to 500°C within 1 h, then heated from 500°C to 800°C within 2 h, then heated from 800°C to 1100°C within 2 h, and then continuously heated from 1100°C to 1180°C within 2 h. It is kept at 1180°C for 1 h and then cooled in the furnace to obtain lightweight and high-strength ceramsite.

[0071] According to the industry standard "GBT17431-2010 Lightweight Aggregates and Their Test Methods", the performance of the lightweight and high-strength ceramsite prepared in Example 3 was tested. The results were as follows: the apparent density was 1410 kg / m 3 , the bulk density was 804 kg / m 3 , the water absorption rate was 6.5%, and the cylinder compressive strength was 20.2 MPa.

[0072] Example 4

[0073] A method for preparing lightweight and high-strength ceramsite using aluminum ash consists of the following steps:

[0074] (1) First, the aluminum ash, gasification slag, and ferrosilicon ash are dried at 105°C, and then, by mass percentage, 86% of aluminum ash, 5% of gasification slag, 5% of ferrosilicon ash, 4% of bentonite, and an external additive are mixed to obtain a mixed material; the mass of the external additive is 2% of the total mass of aluminum ash, gasification slag, ferrosilicon ash, and bentonite, and the external additive is 1% of pulverized coal and 1% of silicon carbide; the aluminum ash, gasification slag, and ferrosilicon ash all pass through a 200-mesh sieve;

[0075] (2) Water is added to the mixed material obtained in step (1), and then pelletizing, aging, and drying are carried out in sequence to obtain the fired ceramsite; the rotation speed of the pelletizing machine during pelletizing is 18 r / min; the aging time is 12 h; the drying temperature is 105°C, the drying time is 3 h, and the drying is carried out in an electrothermal blast drying oven; the particle size range of the fired ceramsite is 7 - 18 mm;

[0076] (3) The fired ceramsite obtained in step (2) is first heated from room temperature to 200°C within 2 h, then heated from 200°C to 500°C within 1 h, then heated from 500°C to 800°C within 2 h, then heated from 800°C to 1100°C within 3 h, and then continuously heated from 1100°C to 1180°C within 2 h. It is kept at 1180°C for 3 h and then cooled in the furnace to obtain lightweight and high-strength ceramsite.

[0077] According to the industry standard "GBT17431-2010 Lightweight Aggregates and Their Test Methods", the performance of the lightweight and high-strength ceramsite prepared in Example 4 was tested. The results were as follows: the apparent density was 1493 kg / m 3 , the bulk density was 898 kg / m3 , the water absorption rate is 5.5%, and the cylinder compressive strength is 23.7 MPa.

[0078] Comparative Example 1

[0079] The preparation method of lightweight ceramsite provided by Patent CN115849943A consists of the following steps:

[0080] (1) By mass percentage, 5-8% of aluminum ash, 62-75% of sludge, and 20-30% of microsilica powder are mixed to obtain a mixed material;

[0081] (2) Water is added to the mixed material obtained in step (1), and then pelletizing, aging, and drying are carried out to obtain the ceramistite to be fired; the rotation speed of the pelletizing machine during pelletizing is 28 r / min; the aging time is 8 h; the drying temperature is 100 °C, and the drying time is 3 h. The drying is carried out in an electrothermal blast drying oven; the particle size range of the ceramistite to be fired is 5-16 mm;

[0082] (3) The ceramistite to be fired obtained in step (2) is heated to 400 °C - 600 °C at a rate of 10 °C / min and preheated for 10-35 min; then it is heated to 1000-1200 °C at a heating rate of 10 °C / min and roasted for 20-45 min. After natural cooling to room temperature, the lightweight ceramsite is obtained.

[0083] According to the industry standard "GBT17431-2010 Lightweight Aggregates and Their Test Methods", the performance of the lightweight ceramsite prepared in Comparative Example 1 was tested, and the results were: water absorption rate ≤ 10%, cylinder compressive strength ≥ 3 MPa, bulk density range ≤ 600 kg / m 3 .

[0084] Compared with the lightweight high-strength ceramsite prepared in Example 1 of the present invention, the strength of the lightweight ceramsite obtained in Comparative Example 1 is far lower than 19.4 MPa in Example 1 of the present invention.

[0085] Comparative Example 2

[0086] The preparation method of lightweight ceramsite provided by Patent CN114057465A consists of the following steps:

[0087] (1) Its raw materials are, by mass parts, 25-35 parts of waste aluminum ash, 15-30 parts of iron tailings, 15-25 parts of cement, 12-18 parts of fly ash, 5.0-7.0 parts of activator, 1.5-2.5 parts of pore-forming agent, and 2.0-2.5 parts of water glass;

[0088] Other conditions are the same as those in Example 1.

[0089] According to the industry standard "GBT17431-2010 Lightweight Aggregates and Their Test Methods", the performance of the lightweight ceramsite prepared in Comparative Example 2 was tested, and the results were as follows: the cylinder compressive strength was 3.3 - 4.2 MPa, the bulk density was 900 - 950 kg / m 3 and the apparent density was 1000 - 1200 kg / m 3 , and the water absorption rate was ≤ 20%.

[0090] Compared with the lightweight high-strength ceramsite prepared in Example 1 of the present invention, the strength of the lightweight ceramsite obtained in Comparative Example 2 was far lower than 19.4 MPa in Example 1 of the present invention.

[0091] Comparative Example 3

[0092] The preparation method of the lightweight ceramsite provided by Patent CN113979775A consists of the following steps:

[0093] In step (1), the raw materials are 50 - 80% of aluminum ash and 20 - 50% of coal gangue by mass percentage;

[0094] In step (3), the firing process is to directly heat up to 1200 - 1400 °C for firing;

[0095] Other conditions are the same as those in Example 1.

[0096] According to the industry standard "GBT17431-2010 Lightweight Aggregates and Their Test Methods", the performance of the lightweight ceramsite prepared in Comparative Example 3 was tested, and the results were as follows: the volume density was ≥ 1420 kg / m 3 , and the apparent density was ≥ 2560 kg / m 3 .

[0097] Compared with the lightweight high-strength ceramsite prepared in Example 1 of the present invention, the density of the lightweight ceramsite obtained in Comparative Example 3 was greater, the mass of the same volume was heavier, and the mass of the ceramsite prepared by the present invention was lighter.

[0098] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing lightweight high-strength ceramsite using aluminum ash, comprising the following steps: (1) Mix 60-86% of aluminum ash, 5-20% of fumed slag, 5-20% of ferrosilicon ash, 4-10% of bentonite and an external additive to obtain a mixed material; The total mass percentage of the aluminum ash, fumed slag, ferrosilicon ash and bentonite is 100%; the mass of the added additive is 2-4% of the total mass of the aluminum ash, fumed slag, ferrosilicon ash and bentonite; (2) adding water to the mixture obtained in step (1), and then sequentially performing balling, aging and drying to obtain ceramsite to be fired; (3) The ceramsite to be fired obtained in step (2) is first heated from room temperature to 200°C within 1-2 hours, then heated from 200°C to 500°C within 1-2 hours, then heated from 500°C to 800°C within 2-3 hours, then heated from 800°C to 1100°C within 2-3 hours, and finally fired at a temperature of 1100-1240°C to obtain lightweight and high-strength ceramsite; The external additives in step (1) are coal powder and silicon carbide; The sintering operation in step (3) is specifically as follows: firstly, the temperature is raised from 1100°C to 1140-1240°C within 1-2 hours, and then the temperature is kept at 1140-1240°C for 1-3 hours.

2. The method according to claim 1, characterized in that In the step (1), the particle sizes of the aluminum ash, the fumed slag and the ferrosilicon ash are independently ≥ 200 mesh.

3. The method according to claim 1, characterized in that In the step (1), the aluminum ash, gasified slag and ferrosilicon ash are dried before mixing, and the drying temperature is 85-105°C.

4. The method according to claim 1, characterized in that: In the step (2), the rotation speed of the ball forming machine during ball forming is 18-36 r / min.

5. The method according to claim 1, characterized in that The aging time in step (2) is 8 to 12 hours.

6. The method according to claim 1, characterized in that The drying temperature in step (2) is 85-105° C. and the drying time is 3-5 hours.

7. The method according to claim 1, characterized in that The particle size of the ceramsite to be fired in step (2) is 3-18 mm.

8. The lightweight and high-strength ceramsite prepared by the method according to any one of claims 1 to 7.