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Protective slag of large-profile round billet continuous-casting crystallizer and method for preparing same

A technology of mold mold slag and continuous casting mold, which is applied in the field of steelmaking auxiliary materials, can solve the problems of increased meniscus fluctuation, deterioration of billet quality, slag inclusion and wrinkled skin, etc., and achieves good fluidity and spreadability, Improve the quality of casting slab and good thermal insulation performance

Active Publication Date: 2013-10-09
HENAN TONGYU METALLURGY MATERIALS GRP
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AI Technical Summary

Problems solved by technology

The reasons for the deterioration of the billet quality are as follows: ① Due to the high casting speed, the amount of molten steel injected into the mold per unit time is large, and the mold has a small buffering effect on the high-speed steel flow due to its small volume, so that the molten steel in the mold Intensified fluctuations in the surface of the meniscus are likely to be involved in slag and inclusions; intensified fluctuations in the meniscus often cause defects such as cracks, pits, inclusions, and pores in the billet, and at the same time make it difficult to maintain the slag layer on the molten steel surface of the mold; During the process, the temperature field distribution of the wall of the slab crystallizer is uneven (especially near the nozzle), and the thickness of the solidified slab shell is uneven under the strong erosion of the stream, which is easy to cause cracks in the slab
[0004] However, for the production of wide-slab steel plates by high-speed continuous casting, due to the large width-thickness ratio of slab continuous casting, the contact area between molten steel per ton of steel and the wall of the crystallizer is large, and the cooling rate of molten steel is faster than that of other types of slabs. The solidification speed of molten steel is fast, and the liquid surface temperature of the mold is low, resulting in poor melting conditions of mold slag, which may easily cause defects such as slag inclusions and wrinkled skins on the surface and subcutaneous of the casting slab; Larger tensile stress, this tensile stress is also one of the main reasons for longitudinal cracking of slabs, with the increase of slab width, the occurrence rate of longitudinal cracks tends to increase
[0005] Due to the above-mentioned problems in the production of wide slabs by high-speed continuous casting, higher requirements are placed on the performance of the mold flux. At present, some imported mold fluxes such as the mold flux produced by the German Stoberg company can solve the above problems, but The cost of imported mold powder is high and it is not suitable for large-scale promotion

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] The technical scheme of the present invention is described below with specific examples, but protection scope of the present invention is not limited thereto:

[0028] Example 1

[0029] The composition of mold flux is as follows:

[0030] SiO 2 28.4%, CaO 29.9%, MgO 2.2%, Fe 2 o 3 1.2%, Al 2 o 3 7.5%, Na 2 O 4.8%, F 2.2%, MnO 1.7%, C 固 17.2%, H 2 O 0.33%, the balance is loss on ignition, K 2 O, TiO 2 and other impurities.

[0031] For every 100 parts of raw materials, take 62 parts of premelt, 8 parts of cement clinker, 5 parts of aluminum barium soil, 1 part of quartz powder, 2 parts of sodium carbonate, 1 part of fluorite, 2.5 parts of manganese carbonate, and 1.5 parts of semi-reinforcing carbon black , 17 parts of scaly graphite. Grind the above raw materials until the particle size is no more than 300 mesh, then mix them thoroughly for 1 hour, add 2.5% sodium carboxymethyl cellulose as a binder, and grind them with water for 2 hours to obtain a slurry wi...

Embodiment 2

[0032] Embodiment 2 (Examples 2 and 3 change the mold powder composition within the allowable range)

[0033] The composition of mold flux is as follows:

[0034] SiO 2 31.1%, CaO 27.1%, MgO 2%, Fe 2 o 3 1.2%, Al 2 o 3 6.3%, Na 2 O 6.1%, F 3.4%, MnO 1.2%, C 固 17.5%, H 2 O 0.33%, the balance is loss on ignition, K 2 O, TiO 2 and other impurities.

[0035] For every 100 parts of raw materials, take 64 parts of premelt, 2.0 parts of cement clinker, 3.5 parts of alumina barium soil, 2.5 parts of quartz powder, 3.5 parts of sodium carbonate, 3.5 parts of fluorite, 2.0 parts of manganese carbonate, and 2.0 parts of semi-reinforcing carbon black , 17 parts of scaly graphite; the above raw materials are pulverized to a particle size of not more than 300 mesh, then fully mixed for 1 hour, adding 2.2% (added amount) sodium carboxymethyl cellulose as a binder, and milled for 2 hours to obtain a concentration of 58 % slurry, the mold flux can be obtained after spray drying.

Embodiment 3

[0037] The composition of mold flux is as follows:

[0038] SiO 2 31.5%, CaO 24.1%, MgO 1.2%, Fe 2 o 3 1.0%, Al 2 o 3 6.0%, Na 2 O 8.8%, F 3.5%, MnO 0.8%, C 固 18.0%, H 2 O 0.33%, the balance is K 2 O, TiO 2 etc. (impurities).

[0039] For every 100 parts of raw materials, take 60 parts of premelt, 3.0 parts of bauxite, 4.5 parts of quartz powder, 7.5 parts of sodium carbonate, 4.0 parts of fluorite, 1.5 parts of manganese carbonate, 2.5 parts of semi-reinforcing carbon black, and 17 parts of scaly graphite Grinding the above raw materials until the particle size is not greater than 300 mesh, then fully mixing for 1 hour, adding 3% sodium carboxymethyl cellulose as a binder, milling with water for 2 hours, to obtain a slurry with a concentration of 58%, and spray drying to obtain the obtained The above-mentioned mold powder.

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Abstract

The invention discloses a protective slag of a large-profile round billet continuous-casting crystallizer and a method for preparing same. The protective slag comprises the following components by weight percentage: 27-33% of SiO2, 24-30% of CaO, 1-3% of MgO, not more than 2% of Fe2O3, 5-10% of Al2O3, 4-9% of Na2O, 1-4% of F, 0.5-2.5% of MnO and 15-20% of C (solid). The components of the protective slag of the continuous casting crystallizer are selected according to the regions of fake siliceous lime in a three-element system CaO-SiO2-Al2O3; out of the components for composing the protectiveslag, the CaO is taken as a main alkaline material, the SiO2 is taken as a main acid material, the Na2O, the CaF2 and the Li2O are taken as main flux agents, and the carbon component is taken as a framework material and a fusing speed controlling agent. By organic combination of the basic materials and the flux agents, the chemical components of the protective slag are adjusted, so as to adjust the physico-chemical indexes of the protective slag, such as fusing temperature, viscosity, crystallization performance, absorbing and including capability, heat conducting capability and the like and meet the requirements of keeping normal slag consumption, thickness of liquid slag layer and reasonable heat conducting amount under a special profile condition, thus ensuring the thickness of the billet shell at the outlet end of the crystallizer and realizing non-gluing continuous casting production.

Description

technical field [0001] The invention belongs to the technical field of steelmaking auxiliary materials, in particular to a large-section round billet billet continuous casting mold mold powder and a preparation method thereof. Background technique [0002] Continuous casting mold powder is an important material in continuous casting production and a necessary means to produce defect-free slabs. Continuous casting mold slag has five functions in the crystallizer: to isolate the air and prevent the secondary oxidation of molten steel; to insulate and keep heat to prevent partial condensation on the surface of molten steel; to purify the interface of molten steel and absorb floating inclusions in the steel; to lubricate the surface of the cast slab to reduce the resistance of casting ; Improve solidification heat transfer between slab and mold. The performance of continuous casting mold flux directly affects the surface quality and internal quality of the slab and even the yie...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22D11/111
Inventor 张国令朱云峰罗志刚徐润玉
Owner HENAN TONGYU METALLURGY MATERIALS GRP
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