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Tengfei Building Materials
The composition control of synthetic refining slag can effectively control the amount and type of slag inclusion in steel
Release time:
2021-01-04
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The main constituents of LF refining slag are CaO, SiO2 and AL2O3. According to the requirements of ternary phase diagram and inclusions, the composition of the refining slag is determined, and the basic law of the slag structure is used according to the known phase equilibrium diagram, and the requirements of experience and process conditions are combined to design reasonable chemical composition of the base slag.
The component of the refining slag that can effectively control the form of inclusion should be wollastonite or similar components. Wollastonite has the advantages of low oxygen potential, low melting point and easy absorption of inclusions generated by deoxidation, especially Al203. Moreover, when wollastonite is mixed with a small amount of fluorite or Al203, the melting point will fall to 1200℃.
Mainly adopt the following technological measures:
(1) Pre-desulfurization of hot metal, the content of S of molten steel into LF furnace ≤ 0.01%, to create conditions for the use of low alkalinity slag;
(2) Add wollastonite and similar components to make low alkalinity synthetic refining slag, extend slag washing time, and improve the ability to remove Class B and D inclusions;
(3) Special deoxidizer and alloy deoxidization are used;
(4) No A is added in the refining process to reduce the content of Al203 in the slag. At the end of refining, the content of Al203 in the slag is controlled at about 8%. The ultimate purpose of refining is to control Al2O3 in the inclusion at about 20%.
(5) Ensure the effect of VD vacuum treatment and the static blowing time after treatment, so that inclusions fully collide, gather and float up to remove.
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