Method and system for preparing light ceramsite from high-temperature molten slag

Abstract

The invention discloses a method and system for preparing light ceramsite from high-temperature molten slag, and belongs to the technical field of industrial solid waste resource utilization. The method comprises the following steps: feeding furnace slag, steel slag or ferromolybdenum slag with the temperature higher than 1400 DEG C into a vertical or horizontal holding furnace, adding industrial solid waste additives such as fly ash and coal gangue, and completing ore phase reconstruction through mechanical or airflow stirring; the reconstructed high-temperature slag is dispersed into balls through high-speed air flow carrying coal gangue ball cores, and the balls enter a horizontal rotary holding furnace with the temperature not lower than 900 DEG C to adjust a hole structure; and finally, screening by a drum screen to obtain the light ceramsite with the particle size of 1-25mm. The density grade of the prepared ceramsite is 300-900, the cylinder compressive strength is 3-11 MPa, and the water absorption rate is less than 10%. Energy self-sufficiency is achieved through latent heat of the high-temperature molten slag, all the raw materials are industrial solid waste, the ceramsite production cost can be reduced, solid waste pollution is reduced, and the method is suitable for production of lightweight concrete aggregates of projects such as buildings, roads and bridges.

Description

Technical Field

[0001] This invention belongs to the field of industrial solid waste resource utilization technology, specifically relating to a method and system for preparing lightweight ceramsite from high-temperature molten slag. Background Technology

[0002] High-temperature slag is a waste product generated during metal smelting, mainly containing elements such as Ca, Si, Al, Mg, and Fe. On the one hand, due to the high-temperature process exceeding 1450℃, the mineral phase structure in most high-temperature slags is stable and has low activity, making them difficult to fully utilize, such as steel slag and ferromolybdenum slag. Traditional disposal methods involve open-air stockpiling or landfilling, which easily causes secondary pollution. On the other hand, the temperature of high-temperature slag discharged from metallurgical furnaces is mostly above 1450℃, resulting in a large amount of energy waste due to energy emission. How to simultaneously utilize the resources of metallurgical slag and recover and utilize the sensible heat of the waste slag is a new direction for achieving the dual carbon goals of the metallurgical industry.

[0003] Guided by the national dual-carbon strategy, lightweight concrete, required by the building materials industry, has gained attention due to its advantages such as light weight, thermal insulation, and sound insulation. Among these, lightweight expanded clay aggregate (Cephalotaxus fortunei) prepared from industrial solid waste is a focus of attention as an aggregate for lightweight concrete. However, the lightweight expanded clay aggregate currently on the market is mainly produced from clay, shale, and coal gangue as raw materials, using pulverized coal or natural gas as fuel, consuming a large amount of resources and energy.

[0004] Utilizing the chemical composition of high-temperature slag and its abundant latent heat to achieve synergistic effects in metal smelting and ceramsite production is of great significance for the dual objectives of the metallurgical industry and for low-carbon production in the building materials industry. Currently, there are no reports on this topic. Summary of the Invention

[0005] To address the above problems, this invention provides a method for preparing lightweight ceramsite using high-temperature molten slag, comprising the following steps: Step 1: The high-temperature molten slag is fed into the mixing furnace, and one or more additives from fly ash, coal gangue, gasification slag, and red mud are added. Step 2: Use mechanical stirring or airflow stirring to stir the materials in the mixing furnace evenly, and at the same time complete the mineral phase reconstruction reaction; Step 3: The reconstructed high-temperature slag flows out from the bottom outlet of the mixing furnace and is dispersed into balls by the high-speed airflow carrying the ball-generating cores. The balls enter the holding furnace and simultaneously encapsulate the ball-generating cores inside, forming high-temperature material balls. Step 4: The high-temperature pellets are kept at a constant temperature in a heat-insulating furnace to complete the pore structure adjustment and form ceramsite; Step 5: The ceramsite flowing out of the heat preservation furnace enters the drum screen and is screened to obtain lightweight ceramsite products with different particle sizes; the lightweight ceramsite is a porous spherical particle with a particle size of 1mm-25mm, a density grade of 300-900, a cylinder compressive strength of 3MPa-11MPa, and a water absorption rate of less than 10%.

[0006] Preferably, the high-temperature slag is furnace slag, steel slag or ferromolybdenum slag, and the temperature is higher than 1400°C.

[0007] Preferably, the mixing furnace in step 1 is a vertical or horizontal structure.

[0008] Preferably, the airflow stirring method in step 2 is as follows: an air cap is provided at the bottom of the mixing furnace, and airflow flows in at high speed through the air cap to stir the internal materials and achieve mixing.

[0009] Preferably, the mechanical stirring method in step 2 is as follows: the mixing furnace rotates itself, driving the internal materials to rotate in order to achieve mixing.

[0010] Preferably, the mechanical stirring method in step 2 is as follows: the mixing furnace is equipped with high-temperature resistant stirring blades, and the material is moved by the rotation of the blades to achieve mixing.

[0011] Preferably, the balloon nucleus in step 3 is a coal gangue particle with a diameter of less than 1 mm.

[0012] Preferably, the heat preservation furnace in step 4 is a horizontal rotary furnace, and the temperature inside the heat preservation furnace is not lower than 900°C.

[0013] Preferably, the ambient temperature of the mineral phase reconstruction reaction in step 2 is not lower than 1400℃, and the reaction forms a silicate mineral phase.

[0014] This invention also provides a system for preparing lightweight ceramsite from high-temperature molten slag using the method described above, comprising a mixing furnace, a pelletizing machine, and a holding furnace; the mixing furnace is used to receive high-temperature molten slag and additives and to complete mineral phase reconstruction; the pelletizing machine is a Venturi jet pipe used to receive high-speed airflow and spherical nuclei, and to accelerate the spherical nuclei to 30 m / s; the holding furnace is used to receive the high-speed moving spherical nuclei and the high-temperature molten slag after mineral phase reconstruction, forming high-temperature pellets and completing pore structure adjustment.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 0. Achieving efficient energy recovery and utilization, and reducing production costs. This invention directly utilizes the latent heat carried by the high-temperature slag to complete the mineral phase reconstruction reaction, without the need for additional input of coal powder, natural gas or other fuels to provide a heat source. It effectively recovers the high-temperature sensible heat that was originally wasted in the metallurgical process, and greatly reduces the energy consumption and cost of lightweight ceramsite production, which is in line with the development requirements of carbon emission reduction in the industrial field.

[0016] 1. Promoting the high-value resource utilization of industrial solid waste and reducing environmental pollution. The raw materials for this invention are metallurgical solid waste such as metallurgical slag, steel slag, and ferromolybdenum slag, as well as industrial solid waste such as fly ash, coal gangue, gasification slag, and red mud, which completely replace the natural resources such as clay and shale required for traditional ceramsite production. This method not only dissolves a large amount of industrial solid waste and avoids secondary pollution of soil and water sources caused by open-air dumping or landfilling of solid waste, but also achieves the high-value transformation of solid waste, truly achieving the goal of "turning waste into treasure".

[0017] 2. Achieving Synergistic Development between the Metallurgical and Building Materials Industries and Expanding Industrial Benefits: This invention breaks down the industrial barriers between the metallurgical and building materials industries, enabling simultaneous and coordinated metal smelting and lightweight ceramsite production. This model can expand the product lines of metallurgical enterprises, improve their overall economic benefits, and simultaneously provide the building materials industry with low-carbon and environmentally friendly lightweight aggregates, promoting the transformation of both industries towards a green and low-carbon direction.

[0018] 3. The prepared ceramsite product has excellent performance and a wide range of applications. The lightweight ceramsite prepared by this invention consists of porous spherical particles with a controllable particle size of 1mm-25mm, a density grade of 300-900, a compressive strength of 3MPa-11MPa, and a water absorption rate of less than 10%, fully meeting the performance requirements of lightweight concrete aggregates. The product can be widely used in the construction of buildings, roads, bridges, and other engineering projects, helping to achieve the upgrade needs of lightweighting, thermal insulation, and sound insulation.

[0019] 4. Simple and easy-to-promote process with strong equipment compatibility. This invention adopts a mineral phase reconstruction method using mechanical stirring or airflow stirring, combined with a process route of air-blown granulation and horizontal rotary furnace heat preservation and hole adjustment. The overall process is simple and controllable. The equipment involved, such as the mixing furnace, pelletizing machine, and heat preservation furnace, is easy to integrate into industrial production and can be connected and modified with existing metallurgical production lines, possessing strong potential for large-scale promotion. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the design framework of the technical solution of the present invention. Detailed Implementation

[0021] The purpose of this invention is to provide a method and system for preparing lightweight ceramsite from high-temperature slag. The method mainly uses high-temperature metallurgical slag and industrial solid waste such as coal gangue, fly ash, and red mud as raw materials, and the latent heat of high-temperature slag as energy. Lightweight ceramsite for concrete is prepared by mineral phase reconstruction and dispersion into pellets, thereby realizing the synergistic production of metal smelting and lightweight ceramsite.

[0022] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method and system for preparing lightweight ceramsite using high-temperature molten slag, wherein the energy required for the production of the lightweight ceramsite is the latent heat of the high-temperature molten slag, the ceramsite consists of porous spherical particles with a particle size of 1mm-25mm, the density grade of the lightweight ceramsite is 300-900, the compressive strength of the cylinder is 3MPa-11MPa, and the water absorption rate is less than 10%.

[0023] This invention also provides a method and system for preparing lightweight ceramsite using high-temperature molten slag, comprising the following steps: Step 1: The high-temperature molten slag is fed into the mixing furnace, and one or more additives from fly ash, coal gangue, gasification slag, and red mud are added. Step 2: Use mechanical stirring or airflow stirring to stir the materials in the mixing furnace evenly, and at the same time complete the mineral phase reconstruction reaction; Step 3: The reconstructed high-temperature slag flows out from the bottom outlet of the mixing furnace and is dispersed into spheres by the high-speed airflow carrying the sphere cores, which then encapsulate the sphere cores to form high-temperature spheres. Step 4: The high-temperature material balls are placed in the heat preservation furnace for heat preservation, and the pore structure is adjusted to form ceramsite; Step 5: The ceramsite flowing out of the heat preservation furnace enters the drum screen and is screened to obtain lightweight ceramsite products with different particle sizes.

[0024] The high-temperature slag described in this invention is furnace slag, steel slag, or ferromolybdenum slag, with a temperature higher than 1400℃. Its main chemical composition is CaO, SiO2, Al2O3, MgO, and Fe2O3. By adding one or more of fly ash, coal gangue, gasification slag, and red mud as additives, the mineral phase of the slag is reconstructed.

[0025] This invention also provides a method for preparing lightweight ceramsite using high-temperature slag. The method is characterized in that the high-temperature slag and additives are mixed in a mixing furnace at a high temperature of over 1400°C to reconstruct the mineral phase composition and structure of the high-temperature slag, adjust its viscosity, and then disperse the reconstructed slag into spheres using high-speed moving coal gangue particles with a particle size of less than 1 mm as sphere cores. The internal pore structure is then adjusted in a heat-insulating furnace to form lightweight ceramsite.

[0026] The mixing furnace is vertical or horizontal, and the materials are mixed by airflow or mechanical stirring.

[0027] In the aforementioned airflow mixing method, an air cap is provided at the bottom of the mixing furnace, through which airflow flows in at high speed, stirring the internal materials to achieve mixing.

[0028] The mechanical stirring method involves the mixing furnace rotating to drive the internal materials to rotate, or the blades inside the mixing furnace rotating to drive the materials to move, thereby achieving material mixing.

[0029] The heat preservation furnace is a horizontal rotary furnace with a temperature of not less than 900℃. High-temperature material balls flow in from one end, complete the mineral phase reconstruction in it, and then flow out from the other end.

[0030] This invention also provides a system for preparing lightweight ceramsite using high-temperature molten slag, comprising: Mixing furnace 1 receives high-temperature molten slag and additives as feed, and completes the mineral phase reconstruction of the high-temperature molten slag; Ball core generator 2 is connected to a high-speed airflow and a ball core feeder, which accelerates the ball core to 30 m / s; The high-speed moving ball-generating ball core generated by the heat-preserving furnace 3 and the ball-generating machine 2, along with the high-temperature molten slag after the mineral phase is reconstructed in the mixing furnace 1, wrap the high-temperature molten slag around the ball-generating ball core to form a 1-25mm high-temperature ball, and complete the adjustment of the internal pore structure of the ball.

[0031] The heat preservation furnace 3 is a rotary furnace, the ball core machine 2 is a Venturi injector, and the mixing furnace is vertical or horizontal.

[0032] Example: Reference Figure 1 The present invention discloses a method and system for preparing lightweight ceramsite using high-temperature molten slag, the scheme of which is as follows: Ingredients: The proportions of each raw material in the heat-insulating furnace are as follows, based on dry weight percentage: 70% high-temperature molten slag, 10% fly ash additives, and 20% coal gangue cores.

[0033] Mineral phase reconstruction: Fly ash and high-temperature slag with additives at a temperature of not less than 1400℃ are fed into mixing furnace 1. While being mixed evenly by airflow or mechanical stirring, the Si, Al, Fe and other components in it form silicate mineral phases such as mullite.

[0034] Pelletizing: After the high-temperature slag, which has been reconstructed into mineral phases, exits the mixing furnace, it adheres to the high-speed moving ball cores ejected by the ball corer. Under the action of surface tension, 1-25mm encapsulated material balls are formed by the high-temperature slag encapsulating the coal gangue ball cores.

[0035] Pore ​​structure adjustment: The coated pellets tumble in the holding furnace, and the gas released from the pellet core, under the action of being wrapped by the high-temperature molten slag above 1200℃, forms pores of different sizes inside the pellets, eventually becoming porous ceramsite.

[0036] Testing: According to GB / T17431.1-2010, lightweight aggregates and their test methods, the main properties of the expanded clay aggregate are as follows: compressive strength 10.1 MPa, bulk density 874 kg / m³, and water absorption rate of 5.3% in 1 hour. It can be used as aggregate for CL50 strength grade concrete.

[0037] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0038] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing lightweight ceramsite using high-temperature molten slag, characterized in that, Includes the following steps: Step 1: The high-temperature molten slag is fed into the mixing furnace, and one or more additives from fly ash, coal gangue, gasification slag, and red mud are added. Step 2: Use mechanical stirring or airflow stirring to stir the materials in the mixing furnace evenly, and at the same time complete the mineral phase reconstruction reaction; Step 3: The reconstructed high-temperature slag flows out from the bottom outlet of the mixing furnace and is dispersed into balls by the high-speed airflow carrying the ball-generating cores. The balls enter the holding furnace and simultaneously encapsulate the ball-generating cores inside, forming high-temperature material balls. Step 4: The high-temperature pellets are kept at a constant temperature in a heat-insulating furnace to complete the pore structure adjustment and form ceramsite; Step 5: The ceramsite flowing out of the heat preservation furnace enters the drum screen and is screened to obtain lightweight ceramsite products with different particle sizes; the lightweight ceramsite is a porous spherical particle with a particle size of 1mm-25mm, a density grade of 300-900, a cylinder compressive strength of 3MPa-11MPa, and a water absorption rate of less than 10%.

2. The method for preparing lightweight ceramsite using high-temperature molten slag according to claim 1, characterized in that, The high-temperature slag is furnace slag, steel slag, or ferromolybdenum slag, and its temperature is higher than 1400℃.

3. The method for preparing lightweight ceramsite using high-temperature slag according to claim 1, characterized in that, The mixing furnace in step 1 is a vertical or horizontal structure.

4. The method for preparing lightweight ceramsite using high-temperature molten slag according to claim 1, characterized in that, The airflow stirring method in step 2 is as follows: a wind cap is set at the bottom of the mixing furnace, and airflow flows in at high speed through the wind cap to stir the internal materials and achieve mixing.

5. The method for preparing lightweight ceramsite using high-temperature molten slag according to claim 1, characterized in that, The mechanical stirring method in step 2 is as follows: the mixing furnace rotates itself, which drives the internal materials to rotate in order to achieve mixing.

6. The method for preparing lightweight ceramsite using high-temperature molten slag according to claim 1, characterized in that, The mechanical stirring method in step 2 is as follows: the mixing furnace is equipped with high-temperature resistant stirring blades, and the material is moved by the rotation of the blades to achieve mixing.

7. The method for preparing lightweight ceramsite using high-temperature slag according to claim 1, characterized in that, The balloon nuclei in step 3 are coal gangue particles with a diameter of less than 1 mm.

8. The method for preparing lightweight ceramsite using high-temperature molten slag according to claim 1, characterized in that, The holding furnace in step 4 is a horizontal rotary furnace, and the temperature inside the holding furnace is not lower than 900℃.

9. The method for preparing lightweight ceramsite using high-temperature slag according to claim 1, characterized in that, In step 2, the ambient temperature for the mineral phase reconstruction reaction is not lower than 1400℃, and the reaction forms a silicate mineral phase.

10. A system for preparing lightweight ceramsite from high-temperature slag, implementing the method of any one of claims 1-9, characterized in that, It includes a mixing furnace, a ball-forming machine, and a holding furnace; the mixing furnace is used to receive high-temperature molten slag and additives and to complete mineral phase reconstruction; the ball-forming machine is a Venturi jet pipe used to receive high-speed airflow and ball-forming ball cores, and to accelerate the ball-forming ball cores to 30 m / s; the holding furnace is used to receive high-speed moving ball-forming ball cores and high-temperature molten slag after mineral phase reconstruction, to form high-temperature ball materials and to complete pore structure adjustment.

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