Separation of Phosphorus- and Iron-Enriched Phase from CaO-SiO 2 -FeO-MgO-P 2 O 5 Melt with Super Gravity
- PDF / 748,908 Bytes
- 4 Pages / 593.972 x 792 pts Page_size
- 38 Downloads / 143 Views
e of the major by-products in steelmaking process, steel slag accounts for 10 to 20 pct output of crude steel. Large quantities of steel slag, because of the existence of phosphorus, are disposed as wastes, resulting in a lot of land resource waste and environment pollution.[1] Therefore, the point is to separate phosphorus from the steel slag, and recycling those useful components like FeO, Fe2O3, MgO, MnO, and CaO back to the iron and steelmaking process. Many researches on enhancing the phosphorus solubility in the P-enriched phase have been carried out by modifying steel slag with different additives such as SiO2,[2] Al2O3,[3] TiO2,[4] and CaF2,[5] before using the magnetic field to separate the P-enriched phase.[6–8] However, due to its micron-level size and embedded distribution in matrix, the P-enriched phase could not be effectively separated by the magnetic field. It is necessary,
CHONG LI, Doctor, JINTAO GAO, Lecturer, and ZHANCHENG GUO Professor, are with the State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, P.R. China. Contact e-mail: [email protected] Manuscript submitted July 10, 2015. Article published online March 29, 2016. 1516—VOLUME 47B, JUNE 2016
therefore, to find a novel method to separate the P-enriched phase from steel slag to promote the steel slag recycling. The effect of super gravity in controlling the distribution of different phases has already been determined and has successfully been applied in the separation and recovery of valuable elements from different kinds of slag,[9–12] as well as in removing impurities from alloy melt.[13,14] Also, as the phosphorus in steel slag is mostly crystallized in solid solution nC2S-C3P, whose density is smaller than the residual melt, and precipitated early during solidification process,[15] it was assumed that the P-enriched phase can be possibly separated by super gravity. Therefore, the separation of phosphorus- and iron-enriched phase from CaO-SiO2-FeO-MgO-P2O5 melt with super gravity was investigated in this study. Under the premise that the slag melt is in the state of solid–liquid two-phase mixture at 1632 K (1350 °C) which is the limiting temperature that the super gravity apparatus can attain, and in order to reduce the melting point and viscosity of the slag melt at this temperature, the slag basicity defined as CaO/SiO2 has been adjusted down to 2.0 and the mass fraction of FeO was added up to 30 pct. The mass fraction of P2O5 and MgO approached the contents in actual steel slag. The chemical composition of the resulting CaO-SiO2FeO-MgO-P2O5 steel slag is listed in Table I; it was prepared by mixing the reagent-grade CaO, SiO2, MgO, 3CaOÆP2O5 ,and synthesized FeO [obtained by reducing Fe3O4 with 5 L/minute flow rate of mixed CO and CO2 with 1:1 proportion at the temperature of 1173 K (900°C)]. The chemical powders were fully mixed and then placed into a magnesia crucible (60 9 120 mm) and heated in the muffle furnace at 1773 K (1500 °C) for 30 minutes in Ar atmosphere to make the powders fully
Data Loading...
