A metallurgical slag water mist impact granulation device system and method

Abstract

This invention discloses a water mist impact granulation device system and method for metallurgical slag, belonging to the technical field of metallurgical slag treatment, granulation forming, and waste heat recovery. The device system includes a slag insulation and storage unit, a tundish flow stabilization unit, a water mist impact granulation nozzle, a gas-liquid two-phase supply unit, a negative pressure or closed granulation collection chamber, a fine powder recovery unit, and a granular slag cooling and waste heat recovery unit. Liquid metallurgical slag, after forming a stable slag flow in the tundish, enters the central channel of the nozzle. Under the shearing, impact, and rapid cooling effects of the annular high-speed water mist and auxiliary airflow, it forms a liquid film, droplets, and granular slag. The granular slag undergoes preliminary solidification in the gas expansion zone and falls into the collection chamber. The fine powder is recovered by a cyclone separator or filter dust collector, and the high-temperature gas or hot water enters the waste heat utilization unit. This invention can reduce the risk of slag adhesion and splashing, improve granulation uniformity and continuous operation stability, and is suitable for the resource-based treatment of blast furnace slag, steel slag, copper slag, nickel slag, and other metallurgical slags.

Description

Technical Field

[0001] This invention relates to the fields of metallurgical slag granulation treatment, sensible heat recovery and solid waste resource utilization, specifically to a metallurgical slag water mist impact granulation device system and method with high-speed water mist impact and auxiliary airflow shear as the core. Background Technology

[0002] Blast furnace slag, steel slag, copper slag, nickel slag and other non-ferrous smelting slags are usually discharged in a high-temperature molten state. They have high discharge temperatures, abundant sensible heat resources, and the slag phase composition has an important impact on their subsequent utilization in building materials, cementitious materials or functional materials.

[0003] While traditional water quenching is a mature technology, it suffers from problems such as high water consumption, steam and sulfide emissions, and difficulty in heat recovery. Dry granulation technology can reduce fresh water consumption and create conditions for waste heat recovery, but when processing slag with high viscosity or large composition fluctuations, it may still encounter problems such as unstable flow, insufficient granulation, particle agglomeration, slag formation on the inner wall of the equipment, and difficulty in controlling fine powder.

[0004] Existing centrifugal granulation, air-quenched granulation, or rotor granulation devices mostly rely on mechanical rotating parts or a single airflow crushing method. When the slag viscosity is high, the flow rate fluctuates greatly, or rapid cooling is required to form a specific glassy phase structure, the particle size distribution and cooling rate are not easily controlled stably. The metallurgical slag granulation and waste heat recovery device in the reference document emphasizes the process organization of slag storage, buffering, granulation, and cooling recovery, but there is still room for improvement in the dedicated structure for high-speed water mist impact rupture, closed collection, fine powder recovery, and low-adhesion continuous operation.

[0005] Therefore, it is necessary to propose a water mist impact granulation device system and method for metallurgical slag, which achieves rapid crushing of molten slag film, rapid solidification of particles, orderly collection of fine powder, and cascade utilization of waste heat through the synergistic effect of water mist impact, auxiliary gas expansion, and closed collection. Summary of the Invention

[0006] The purpose of this invention is to provide a water mist impact granulation device system and method for metallurgical slag, in order to solve the problems of flow fluctuation, wide particle size distribution, particle adhesion, high risk of splashing and difficulty in organizing the recovery of waste heat in the existing metallurgical slag granulation process.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A metallurgical slag water mist impact granulation device system includes a molten slag insulation and storage unit, a tundish flow stabilization unit, a water mist impact granulation nozzle, a gas-liquid two-phase supply unit, a granulation collection chamber, a fine powder recovery unit, and a granular slag cooling and waste heat recovery unit. Liquid metallurgical slag enters the tundish flow stabilization unit from the molten slag insulation and storage unit, where it forms a stable slag flow after slag blocking, flow stabilization, and insulation. The stable slag flow enters the central molten slag channel of the water mist impact granulation nozzle, where it encounters annular high-speed water mist and auxiliary gas at the nozzle outlet. Under the action of impact shearing, surface tension, and rapid cooling, the molten slag forms a liquid film band and is further broken into droplets and granular slag. The granular slag undergoes preliminary cooling and solidification in the gas expansion zone and particle settling zone of the granulation collection chamber before entering the granular slag cooling and waste heat recovery unit. Fine powder and dust-laden gas are purified by the fine powder recovery unit before being discharged or recycled.

[0008] The water mist impact granulation nozzle can adopt a coaxial annular slit type, internal mixing type, external mixing type, or multi-hole array type structure. The central molten slag channel is used to guide the liquid metallurgical slag, the annular water mist channel is used to form a high-speed atomized water jet, and the auxiliary gas channel is used to form a gas expansion zone and enhance liquid film breakup. By adjusting the water pressure, gas pressure, water-gas ratio, molten slag flow rate, and nozzle outlet spacing, the liquid film thickness, droplet size, cooling rate, and particle size distribution can be controlled.

[0009] Therefore, the core innovation and beneficial effects of this invention are as follows: (1) This invention uses high-speed water mist to directly impact and shear the molten slag stream, forming a liquid film and droplet cluster within a short distance, thus improving the molten slag crushing efficiency. (2) By forming a gas expansion zone with auxiliary gas, the probability of particle collision and adhesion can be reduced, and fine powder can be oriented into the recovery unit with the airflow. (3) By using a closed or negative pressure granulation collection chamber, the risk of high-temperature splashing and water vapor escape can be reduced, improving the on-site operating environment. (4) Through the granular slag cooling and waste heat recovery unit, the sensible heat of high-temperature granular slag can be converted into hot air, hot water or steam, realizing the cascade utilization of thermal energy. (5) The device can adjust parameters according to the temperature, viscosity and flow rate of different molten slags such as blast furnace slag, steel slag, copper slag, and nickel slag, making it widely applicable. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the system structure of the metallurgical slag water mist impact granulation device of the present invention.

[0011] Figure 2 This is a flowchart of the metallurgical slag water mist impact granulation method of the present invention.

[0012] Explanation of reference numerals in the attached diagram: 1-Slag insulation and storage unit; 2-Tundish flow stabilization unit; 3-Water mist impact granulation nozzle; 4-Gas-liquid two-phase supply unit; 5-Central slag channel; 6-Annular water mist channel; 7-Auxiliary gas channel; 8-Gas expansion zone; 9-Liquid film zone; 10-Droplets; 11-Particle slag; 12-Particle collection chamber; 13-Fine powder recovery unit; 14-Particle slag cooling and waste heat recovery unit. Detailed Implementation

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. All equivalent substitutions or non-inventive improvements made based on the concept of the present invention should fall within the scope of protection of the present invention.

[0014] Liquid blast furnace slag is discharged from the molten slag insulation and storage unit and enters the tundish flow stabilization unit equipped with an insulation layer and heating device, where the molten slag temperature is maintained at 1350-1550℃. The diameter of the tundish outlet nozzle is 10-60mm, and the molten slag mass flow rate is 1-50t / h. After entering the molten slag channel in the center of the water mist impact granulation nozzle, the molten slag stream is subjected to a combined impact of 0.5-5.0MPa high-pressure water mist and 0.1-0.8MPa auxiliary gas at the nozzle outlet, forming a continuous liquid film. The liquid film breaks into droplets within the gas expansion zone and rapidly solidifies into granular slag, with the main particle size being 0.5-3.0mm.

[0015] The temperature of the liquid copper slag before entering the tundish flow stabilization unit is 1200-1400℃. By adjusting the high-pressure water source pressure, auxiliary gas flow rate, and nozzle outlet angle, the molten slag film rapidly expands and breaks up at the nozzle outlet. For copper slag with high viscosity or large compositional fluctuations, the auxiliary gas velocity can be appropriately increased and the unit water consumption reduced to decrease particle adhesion and excessive steam generation. The granulated slag then enters a moving bed heat exchanger or drum cooler, where the cooling medium is heated and used for drying, preheating, or low-pressure steam preparation.

[0016] The granulation collection chamber adopts a closed structure, with water mist impact granulation nozzles at the top and negative pressure exhaust ports on the sides. These exhaust ports are sequentially connected to a cyclone separator and a bag filter. Fine powder and water vapor generated during granulation are carried by the airflow into the fine powder recovery unit, while larger particles enter the particle settling zone under gravity. By controlling the slight negative pressure within the granulation collection chamber, the risk of dust escape and high-temperature water vapor emission can be reduced.

[0017] The key control parameters of this invention include slag temperature, slag mass flow rate, high-pressure water pressure, auxiliary gas pressure, nozzle outlet spacing, injection angle, and airflow organization in the granulation collection chamber. When the slag temperature is high or the flow rate is large, the water mist pressure and auxiliary gas flow rate can be increased; when the slag viscosity is high, the tundish insulation temperature can be increased, the length of the central slag channel can be shortened, and the nozzle outlet shear strength can be increased; when finer particles are required, the water mist velocity can be increased, the nozzle outlet spacing can be reduced, and the turbulence intensity in the gas expansion zone can be enhanced.

Claims

1. A metallurgical slag water-impingement atomization apparatus system and method, characterized by: The system includes a slag insulation and storage unit, a tundish flow stabilization unit, a water mist impact granulation nozzle, a gas-liquid two-phase supply unit, a granulation collection chamber, a fine powder recovery unit, and a granular slag cooling and waste heat recovery unit. The slag insulation and storage unit is connected to the tundish flow stabilization unit. The slag outlet of the tundish flow stabilization unit is connected to the central slag channel of the water mist impact granulation nozzle. The gas-liquid two-phase supply unit is connected to the annular water mist channel and the auxiliary gas channel of the water mist impact granulation nozzle, respectively. The water mist impact granulation nozzle is arranged in the upper or upper side of the granulation collection chamber. The lower part of the granulation collection chamber is connected to the granular slag cooling and waste heat recovery unit. The upper or side of the granulation collection chamber is connected to the fine powder recovery unit.

2. A metallurgical slag water-impingement atomization device system and method according to claim 1, characterized in that: The water mist impact granulation nozzle includes a central slag channel, an annular water mist channel arranged around the central slag channel, and an auxiliary gas channel located outside or inside the annular water mist channel; the outlet of the central slag channel and the outlet of the annular water mist channel are arranged coaxially, nearly coaxially, or at an angle of 5°-45°, so that the slag stream is subjected to a combined impact of high-speed water mist and auxiliary airflow at the nozzle outlet.

3. A metallurgical slag water-impingement atomization device system and method according to claim 1 or 2, characterized in that: The gas-liquid two-phase supply unit includes a high-pressure water source, a compressed gas source, a pressure stabilizing tank, a flow regulating valve, a pressure sensor, and a flow meter; wherein, the water supply pressure of the high-pressure water source is 0.2-10.0MPa, the auxiliary gas pressure is 0.05-1.5MPa, and the thickness of the molten slag film and the particle size distribution are controlled by adjusting the water-gas ratio and the injection angle.

4. A metallurgical slag water-impingement atomization device system and method according to any one of the preceding claims, characterized in that: The tundish flow stabilization unit is equipped with an insulation layer, a heating device, a slag weir, and a replaceable slag outlet, so that the molten slag entering the water mist impact granulation nozzle forms a continuous and stable stream.

5. A metallurgical slag water mist impact granulation device system and method according to any one of the preceding claims, characterized in that: The granulation collection chamber is a closed, semi-closed, or negative pressure structure, and is equipped with a gas expansion zone, a particle settling zone, and an anti-adhesion lining. The anti-adhesion lining is one or more of the following: a refractory material layer, a wear-resistant alloy layer, a ceramic coating, or a water-cooled wall structure.

6. A metallurgical slag water mist impact granulation device system and method according to any one of the preceding claims, characterized in that: The fine powder recovery unit includes a cyclone separator, a bag filter, a wet scrubber, or a combination thereof, for recovering fine powder and aerosol particles generated during the water mist impact granulation process.

7. A metallurgical slag water mist impact granulation device system and method according to any one of the preceding claims, characterized in that: The granular slag cooling and waste heat recovery unit includes one or more of the following: drum cooler, fluidized bed heat exchanger, moving bed heat exchanger, heat exchange jacket, or waste heat boiler. The cooling medium is air, water, steam, or inert gas.

8. A system and method for metallurgical slag water mist impact granulation according to any one of the preceding claims, characterized in that: The slag is blast furnace slag, steel slag, copper slag, nickel slag, ferroalloy slag, non-ferrous smelting slag, or a mixture thereof, and its temperature before entering the water mist impact granulation nozzle is 50-250℃ higher than the melting point of the corresponding slag.

9. A method for water mist impact granulation of metallurgical slag using the apparatus system described in any one of claims 1-8, characterized in that, The process includes the following steps: S1, feeding the liquid metallurgical slag into the molten slag insulation and storage unit and maintaining its flow; S2, allowing the liquid metallurgical slag to form a continuous and stable slag flow through the tundish stabilization unit; S3, the slag flow enters the molten slag channel in the center of the water mist impact granulation nozzle, where it is sheared, impacted, and stretched into a liquid film at the nozzle outlet by the annular high-speed water mist and auxiliary airflow; S4, the liquid film breaks into droplets in the gas expansion zone and rapidly cools and solidifies into granular slag; S5, the granular slag falls into the granulation collection chamber and enters the granular slag cooling and waste heat recovery unit, while the dust-laden gas enters the fine powder recovery unit; S6, the obtained granular slag is screened, cooled, and utilized for resource recovery.

10. The metallurgical slag water mist impact granulation device system and method according to claim 9, characterized in that: By adjusting the molten slag mass flow rate, high-pressure water pressure, auxiliary gas pressure, nozzle outlet spacing, and nozzle spray angle, the particle size of the granular slag is mainly distributed in the range of 0.1-5.0 mm, preferably 0.5-3.0 mm, and the temperature of the granular slag at the outlet of the granulation collection chamber is reduced to below 600°C, and further cooled to below 200°C by the waste heat recovery unit.

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