CN-121974589-A - Modification method of coal-fired furnace slag and application thereof

Abstract

The invention relates to the technical field of mortar and concrete preparation, in particular to a modification method of coal-fired furnace slag and application thereof. According to the invention, the slag is subjected to crushing and screening, water content control, pore space prefilling of the fly ash-cement mixture, water prefilling and cladding, and modified, so that the porosity of the slag is reduced, the fluidity of the slag is improved, and the mechanical property of the slag is obviously improved. In addition, the modified slag is applied to the production of mortar and concrete, 100% substitution of the slag to natural sand can be realized, the compressive strength of the mortar and concrete can be greatly improved, and the method has remarkable environmental protection and economic benefits.

Inventors

• BAO FUXI
• LI FANGSHENG
• DAN JIANMING
• LUO JIANQIANG
• WANG JINYU
• ZHANG QINGRUI
• SHI KAIGE

Assignees

• 石河子大学

Dates

Publication Date

20260505

Application Date

20260310

Claims (10)

1. 1. A method for modifying coal-fired slag, which is characterized by comprising the following steps: S1, crushing and screening coal-fired furnace slag, and then baking until the water content is lower than 5%; S2, adding a fly ash-cement mixture accounting for 5-15% of the mass of the coal-fired furnace slag, and horizontally stirring at a slow speed to ensure that the furnace slag pores are filled with mixed powder, wherein the mass ratio of the fly ash to the cement in the fly ash-cement mixture is 90:10; S3, adding water accounting for 10-18% of the mass of the coal-fired furnace slag, and stirring at a slow speed.
2. 2. The coal-fired slag modification process according to claim 1, wherein the screening in step S1 is specifically a 4.75 mm screen.
3. 3. The method for modifying coal-fired slag according to claim 1, wherein the water content is lower than 3% in step S1.
4. 4. The method for modifying coal-fired furnace slag according to claim 1, wherein the addition amount of the fly ash-cement mixture in the step S2 is 10% -15% by mass of the coal-fired furnace slag.
5. 5. The method for modifying coal-fired slag according to claim 4, wherein the amount of the fly ash-cement mixture added in the step S2 is 15% by mass of the coal-fired slag.
6. 6. The coal-fired slag modification method according to claim 1, wherein the water is added in an amount of 15 to 18% by mass of the coal-fired slag in step S3.
7. 7. The method for modifying coal-fired slag according to claim 6, wherein the water is added in an amount of 18% by mass of the coal-fired slag in step S3.
8. 8. The method for modifying coal-fired slag according to claim 1, wherein the stirring time in step S2 or step S3 is 3 to 5 min.
9. 9. A modified coal-fired slag prepared by the coal-fired slag modification method of claim 1.
10. 10. Use of the modified coal-fired slag according to claim 1 or the modified coal-fired slag according to claim 9 for the production of high strength mortars or concretes.

Description

Modification method of coal-fired furnace slag and application thereof Technical Field The invention relates to the technical field of mortar and concrete preparation, in particular to a modification method of coal-fired furnace slag and application thereof. Background The coal-fired slag is black ash slag discharged from the bottom of the furnace after coal combustion, and is also called slag, and the annual yield of the slag is about 2 hundred million tons. Depending on the furnace type and the discharge mode, the slag particles vary in size, with the larger being over 30cm and the smaller being only tens of microns. The chemical composition of the slag is basically consistent with that of the fly ash, mainly comprises SiO 2、Al2O3, feO, caO, mgO, a small amount of R 2 O, S, P and the like. The mineral composition of the slag is vitreous, the performance is stable, the remarkable structural characteristics are that the slag is porous and fragile, and the highest porosity can reach 90%. The compressive strength of slag varies from tens of MPa to a few tenths of MPa depending on the porosity. The water absorption of the slag is larger due to the pores, and when the slag is used for producing mortar and concrete, the defects of poor construction performance, low strength, poor stability, unqualified freezing resistance and the like exist, and particularly after the slag is used for producing mortar and concrete by replacing natural sand, the maximum reduction range of the compressive strength of the mortar and concrete is about 50%, so that the wide application of the mortar and concrete is severely restricted. At present, the disposal mode of slag is used for producing building materials except for a small part, and most of the slag is landfill treatment, so that a large amount of land occupation, environmental pollution and resource waste are caused, and the slag is urgently required to be safely disposed and recycled. Mortar and concrete production requires a large amount of sand stones, and the demand of concrete sand stones in China exceeds 150 hundred million tons in 2023, wherein the sand reaches 60 hundred million tons. Along with the strengthening of national environmental protection, china faces serious sand barren. Therefore, the reasonable utilization of solid wastes including coal-fired slag to replace or partially replace natural sand to produce mortar and concrete becomes a necessary choice for solid waste treatment, environmental protection and sustainable development of building material industry. Based on the above, the invention provides a modification method of coal-fired furnace slag and application thereof in producing high-strength mortar or concrete, aiming at achieving the purposes of improving the mechanical property of furnace slag and the working performance of mortar and concrete, and providing technical support for solid waste treatment and high-strength mortar and concrete production. Disclosure of Invention The invention aims to provide a modification method of coal-fired furnace slag and modified coal-fired furnace slag prepared by the method. Another object of the invention is to provide the method for modifying coal-fired slag or the application of the modified coal-fired slag in producing high-strength mortar or concrete. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: The modification method of the coal-fired furnace slag comprises the following steps: S1, crushing and screening coal-fired furnace slag, and then baking until the water content is lower than 5%; S2, adding a fly ash-cement mixture accounting for 5-15% of the mass of the coal-fired furnace slag, and horizontally stirring at a slow speed to ensure that the furnace slag pores are filled with mixed powder, wherein the mass ratio of the fly ash to the cement in the fly ash-cement mixture is 90:10; S3, adding water accounting for 10-18% of the mass of the coal-fired furnace slag, and stirring at a slow speed. Preferably, in the modification method of the coal-fired furnace slag, the screening in the step S1 is specifically a 4.75mm screen. Preferably, in the modification method of the coal-fired furnace slag, the water content is lower than 3% in the step S1. Preferably, in the modification method of the coal-fired slag, the addition amount of the fly ash-cement mixture in the step S2 is 10% -15% of the mass of the coal-fired slag. Further preferably, in the modification method of coal-fired slag according to the present invention, the addition amount of the fly ash-cement mixture in step S2 is 15% of the mass of the coal-fired slag. Preferably, in the modification method of the coal-fired slag, the addition amount of the water in the step S3 is 15-18% of the mass of the coal-fired slag. Still preferably, in the modification method of coal-fired slag according to the present invention, the water is added in an amount of 18% by mass of the coal-fired slag in step