A secondary cooling method for continuous casting of molten steel using nitrogen-water spray cooling

Abstract

A secondary cooling method for continuous casting of molten steel using nitrogen-water spray cooling, which belongs to the field of metallurgical technology and is carried out according to the following steps: (1) pressurize nitrogen to 0.6~1.0MP for storage; (2) pressurize water to 2.0~ 3.0MPa storage; (3) Transport the nitrogen in the nitrogen tank to the secondary air-cooling water nozzle; transport the water in the high-pressure water tank to the secondary air-cooling water nozzle; nitrogen and water should be based on the gas-to-water ratio of 0.8~1.2 (m3×h‑1) / (L×min‑1) mixing; (4) Set the secondary cooling specific water volume to 0.2~1.0L / kg, and spray the gas mist to the surface of the continuous casting billet in each sector section of the secondary cooling zone. The method of the present invention can be applied to the continuous casting production of slabs and blooms, has the characteristics of reducing the amount of gas-water, increasing the metal yield, and is conducive to improving the surface and internal quality of the continuous casting billet, so it has good application prospects. .

Description

technical field [0001] The invention belongs to the technical field of metallurgy, in particular to a secondary cooling method for continuous casting of molten steel using nitrogen-water spray cooling. Background technique [0002] In the process of continuous casting of molten steel, due to the oxidation reaction between the continuous casting slab and the oxygen or water vapor in the secondary cooling atmosphere, a certain amount of oxide scale will be formed on the surface of the continuous casting slab; the generation of oxide scale is not only due to the oxidation loss of metal Reducing the metal yield will also affect the surface and internal quality of the continuous casting slab, which is an important issue that iron and steel production enterprises generally pay attention to. [0003] During the continuous casting process, the molten steel enters the secondary cooling section after forming the primary slab shell in the crystallizer, and solidifies the molten steel u...

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Problems solved by technology

[0004] However, since the current air-water spray cooling of continuous casting secondary cooling uses compressed air to complete the atomization and injection of cooling water, the oxygen in the compressed air and the water vapor formed by the vaporization of cooling water droplets on the surface of the slab will be on the surface of the slab. form H 2 O(g)-O 2 -N 2 The oxidizing atmosphere makes the surface of the slab prone to oxidation and forms oxide scales; field statistics show that the amount of oxide scales in the continuous casting process can reach 0.7~6kg / (m 2 slab surface area), which not only causes a large amount of oxidation loss of metal materials, but also brings surface quality problems of continuous casting slabs or steel products including surface reticular cracks, iron sheet pits, iron sheet pressing, etc.; in addition, continuous casting slabs The formation of surface oxide scale directly affects the heat transfer and cooling effect of the air-water spray on the surface of the continuous casting slab, not only requires a large amount of air and water, but also easily affects the internal quality of the continuous casting slab