Refining slag for ultra-pure steel and preparation method thereof

Abstract

The invention relates the refining slag and preparing method for super clean steel, comprising the following characters: CaOí¦93%, SiO2íœ2%, TiO2íœ100ppm, Al2O3í¦99.5%, TiO2íœ 50ppm. The refining slag comprises the following: CaO45-59%wt, Al2O340-50%wt, SiO21-5%wt, TiO2íœ50ppm, N íœ200ppm, (B+Pb)íœ100ppm, (S+P)íœ200ppm. In the refining slag the impurity and harmful elements content are low, meeting the requirement of super clean steel. That adding the petroleum coke air-captive and barium carbonate research agent reduces the fusion point of super clean steel, accelerates the melting rate, and improves the sulfur-phosphorous specific capacity. The percents of pass of bearing steel and car steel are above 98%, and the international SKF percent of pass of bearing steel is over 90%.

Description

technical field [0001] The invention relates to a refining slag for ultra-pure steel and a preparation method thereof. Background technique [0002] Ultra-pure steel has extremely strict requirements on purity, and the content of unwanted impurities must be strictly controlled. For example, SKF bearing steel requires that N, Ti, As, Sn, and Pb should be controlled to be less than 0.003%, 0.0015%, 0.04%, 0.03%, and 0.0002%, respectively. %, [H]<1.0ppm; X60~100 series oil pipeline steel requirements: [S]<0.001%, T[O]+[S]+[P]+[N]+[H]≤90ppm. In addition to the purification of smelting raw materials, ultra-pure steel smelting also adopts various refining methods to further reduce harmful elements and inclusions. The refining process goal is mainly achieved through refining slag, so the impurities in refining slag must be strictly controlled. If the refining slag itself has impurities And the high content of harmful elements will not only fail to achieve the purpose of refi...

AI Technical Summary

Problems solved by technology

[0012] Various CaO-Al mentioned above 2 o 3 -SiO 2 It is refining slag, only for CaO and Al 2 o 3 , SiO 2 , MgO, etc. are limited, and there are basically no special restrictions on other impurities, so the unwanted harmful element impurities (such as Ti, Na, H, N, Pb, B, Pb) is not particularly limited, for example, aluminum slag contains K, Na compounds, usually SiO in alumina 2 Content above 6%, TiO 2 The content is more than 3%, S and P are also high, fluorite not only erodes the lining, but also has harmful F - , witherite has high impurity content of sulfur, silicon and iron oxide, and the binder contains harmful components such as hydrogen, sodium and crystal water, resulting in low purity of the obtained refining slag itself, TiO 2 , CaF 2 、Na 2 CO 3 , H, N and other harmful components are high, and become the source of inclusions and harmful elements in ultra-pure steel, such as TiO in refining slag 2 >100ppm, it will cause the refined bearing steel [Ti] to exceed the standard

Therefore, the above refining slags are not suitable for ultra-pure steel refining

Moreover, the preparation of the above-mentioned refining slag cannot reduce or remove the harmful components in the raw materials, and even lead to the increase of harmful components, such as the use of binders for pelletizing