宝钢低夹杂物精炼.pdf

PROGRESS OF PRODUCTION TECHNOLOGY OF
CLEAN SITEELIIN BAOSTTEEL
CU1 Jian ZHENG Yiyu ZHU Lixin
(Baoshan Iron and Steel Co, Ltd.
Abstraca: The progress in control technology of carbon, nitrogen, total oxygen
phosphorus, and sulphur as well as inclusions in steel is discussed at Baosteel. The purity
obtained in IF steel and pipeline steel is introduced
Keywords: Clean steel; IF steel, Pipeline steel, Steelmaking
1 Prefab
The so-called clean steel generally is the steel in which the content of impurit
lements, such as phosphorus, sulphur, total oxygen, nitrogen, hydrogen(includin carbon
sometimes )and inclusions, should be very low. The so-called impurity elements can
change with different grades of steel. One element is a kind of harmful impurity in certain
steel grade. It may be not harmful enough, even may be useful in another grade. In other
words, the control elements are different for different performance demands of steel. For IF
steel, the content of carbon, nitrogen, total oxygen and inclusions In steel should be as low
as possible in order to gain good stretchability, high r value, perfect surface quality and
reduce the amount of the micro-alloy elements. The high quality pipeline steel should have
ultra low sulphur, low phosphorus, low nitrogen, low total oxygen content and a certain
ratio of Ca/S
Since the middle period of 1990s, Baosteel has endeavored to develop the melting
technology of clean steel. The research work concentrates on the development of relativel
Individual technologies and mass production of high cleanliness steel(F steel, pipeline
steel etc.
This paper presents the progress of production technologies of clean steel in Baosteel
2 Progress of individual production technology of clean steel
2.1 Production technology of ultra-low sulphur steel
The desulphurization in hot metal is a kind of economical and effective
desulphurization method, which has been widely used in steelmaking production. Two
kinds of desulphurization patterns in torpedo car(Cao based flux, Cac2 based flux)and
hot metal ladle (Mg based flux )were developed in Baosteel. When the original sulphur
content is between 150ppm(ppm=10)and 300ppm, the sulphur content of hot metal can
decrease to 1 Oppm to 30ppm atter the desulphurization
It is well known that desulphurization ability of BOF is fairly limited. When the
original sulphur content of hot metal is very low, the sulphur pick-up phenomenon in BOF
often occurs because of the addition of lime and scrapwith higher sulphur content. In