Behavior of phosphorus enrichment in dephosphorization slag at low temperature and low basicity
- PDF / 1,271,171 Bytes
- 10 Pages / 592.8 x 841.98 pts Page_size
- 30 Downloads / 177 Views
Behavior of phosphorus enrichment in dephosphorization slag at low temperature and low basicity Ge-fan Ye, Jian Yang, Run-hao Zhang, Wen-kui Yang, and Han Sun State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China (Received: 7 January 2020; revised: 4 March 2020; accepted: 6 March 2020)
Abstract: At low basicity and low temperature, the dephosphorization behavior and phosphorus distribution ratio (LP) between slag and molten steel in the double slag and remaining slag process were studied with a 180 t basic oxygen furnace industrial experiment. The dephosphorization slags with different basicities were quantitatively analyzed. At the lower basicity range of 0.9–2.59, both LP and dephosphorization ratio were increased as the basicity of dephosphorization slag increased. Dephosphorization slag consisted of dark gray P-rich, light gray liquid slag, and white Fe-rich phases. With increasing basicity, not only did the morphologies of different phases in the dephosphorization slag change greatly, but the area fractions and P2O5 content of the P-rich phase also increased. The transfer route of P during dephosphorization can be deduced as hot metal → liquid slag phase + Fe-rich phase → P-rich phase. Keywords: dephosphorization; basicity; phosphorus-rich phase; slag; converter steelmaking
1. Introduction Multi-refining converter (MURC) process [1], which was developed by Nippon Steel, is the dephosphorization process in basic oxygen furnace (BOF) that can markedly decrease calcium oxide (CaO) consumption and waste slag emission. Desilication and dephosphorization are first conducted. After intermediate deslagging by tilting the furnace, decarburization is further performed in the same converter. Then, the decarburization slag is left after tapping and reused for the dephosphorization in the next heat because of the lower temperature at the early stage of converter blowing, which is favorable to dephosphorization. Therefore, consumption of lime and light-burned dolomite can be greatly reduced along with the emission amount of waste slag. According to the report [2], the lime consumption is reduced by 40% compared with the conventional BOF process during the entire converter blowing. To steadily enhance the deslagging ratio of the MURC process by more than 70%, we have to adjust the slag composition and top-blowing lance position to control the slag-foaming condition [3]. Regarding the effects of dephosphorization operation parameters in the double slag and remaining slag process similar to MURC, Wang et al. [4] found that the fluidity of the dephosphorization slag can be improved at lower basicity
(R of 1.3–1.5), and the slag has a moderately foaming property, thereby enhancing the deslagging ratio after dephosphorization. Yang et al. [5] studied the effect of operation factors on dephosphorization performance under the lower initial phosphorus content less than 0.09wt% of hot metal; they reported that dephosphorization is determined by the
Data Loading...
