Thermochemical Aspects of Boron and Phosphorus Distribution Between Silicon and BaO-SiO2 and CaO-BaO-SiO2 lags

Abstract

In the production of solar grade silicon by metallurgical route the distribution of B and P between slags and liquid silicon is the most important key issue. The equilibrium and thermochemistry of reactions between liquid silicon and BaO-SiO 2 slags and up to 10% BaO-containing CaO-BaO-SiO 2 slags is studied through experimental work and using thermodynamic calculations. It is shown that the distribution coefficient of B (L B ) is higher for the CaO-BaO-SiO 2 slags than that for BaO-SiO 2 slags and it is not significantly affected by temperature and composition changes of the slags. In contrast, the distribution coefficient of P (L P ) is higher for BaO-SiO 2 slags than that for the CaO-BaO-SiO 2 slags, and it is higher at lower temperatures. The chemical activities of the dilute solutions of Ba in liquid silicon, and the dilute solutions of B 2 O 3 , P 2 O 5 and BaO in the slags are calculated. Moreover, the reaction mechanisms for B, P, Ba and Ca transport between liquid silicon and the slags are explained.

The Establishment of Thermodynamic Model for Ti Bearing Steel-Slag Reaction and Discuss

“…Cheng, (2010); Jiang et al (2016); Li and Cheng, ( 2019) , 2005;Sun et al, 2015;Safarin, 2019) are calculated by this paper's IMCT model, and compared with their experiment results (Gzieo and Jowsa, 1984;Nomura et al, 1991;Hino, 1994;Kishi et al, 1994;Ohta and Suito, 1994;Ohta and Suito, 1998a;Ohta and Suito, 1998b;Moeizane et al, 1999;Jung and Fruehan, 2001;Stolyarova et al, 2005;Sun et al, 2015;Safarin, 2019) and Factsage-7.0 calculating values, as shown in Figure 4. In Figure 4A or The dependence of C/S ratio in the slag (S1), listed in Table 2, on the ΔG of reactions 1-3 was shown in Figure 5.…”

Effects of La2O3 Addition into CaO-SiO2 Slag: Structural Evolution and Impurity Separation from Si-Sn Alloy

“…[3] Taking the ELKEM solar process developed in Norway as an example, [4] around 60 pct energy consumption and 90 pct CO 2 emission can be reduced through the combination of metallurgical refining techniques, respectively, slag refining, acid leaching, and directional solidification. In the above refining techniques, slag refining [5][6][7] and acid leaching [8,9] are targeted for the removal of the most challenging impurities boron (B) and phosphorus (P) from the crude metallurgical-grade silicon (MG-Si).…”

“…To date, considerable work has been done to investigate the effect of slag properties on the B removal efficiency. A number of slag systems have been studied and reviewed, [7,[11][12][13][14] such as CaO-SiO 2 , [15][16][17][18][19] CaO-MgO-SiO 2 , [20][21][22] CaO-BaO-SiO 2 , [6,18] CaO-Na 2 O-SiO 2 , [5,23,24] CaO-ZnO-SiO 2 , CaO-Al 2 O 3 -SiO 2 , [25][26][27] CaO-MgO-Al 2 O 3 -SiO 2 , [28,29] CaO-SiO 2 -CaCl 2 , [30][31][32] CaO-SiO 2 -CaF 2 , [24,33,34] and so on. The B removal ability of different slags can be evaluated by the widely used B distribution coefficient (L B ) between the slag and metal in molten state:…”