Carbide Capacity of CaO-SiO2-CaF2(-Na2O) Slags at 1773 K

Abstract

The influence of CaF 2 , Na 2 O, and basicity on the solubility of carbon in the CaO-SiO 2 -CaF 2 -Na 2 O slag at 1 773 K was investigated on the basis of carbide capacity concept. The carbide capacity of the CaO satdSiO 2 -CaF 2 system increases with increasing CaF 2 content up to about 40 mass%, followed by nearly constant value. The capacity of the slags saturated with Ca 2 SiO 4 also increases with increasing the content of CaF 2 and this trend can be explained from the depolymerization reaction of silicate network by F Ϫ ions. The carbide capacity of the slags increases by increasing the ratio of (%CaF 2 )/(%SiO 2 ) up to about 0.8, followed by slight increase or nearly constant value at a fixed CaO content. The capacity also increases by increasing the ratio of (%CaO)/(%SiO 2 ) at a fixed CaF 2 content. The carbide capacity of the Na 2 O-containing slags linearly increases with increasing the basicity, B (ϵ{(%CaO)ϩ(%Na 2 O)}/(%SiO 2 )) and the dependence of the capacity on the basicity decreases by increasing the CaF 2 content. On the other hand, the capacity decreases with increasing CaF 2 content at basicity, B of the slags greater than about 2.0 and vice versa in the composition of BՅ2.0. The capacity of the slags containing CaF 2 and Na 2 O could quantitatively be described by the activity of CaO rather than optical basicity.

Carbide Capacity of CaO–SiO2–MnO Slag for the Production of Manganese Alloys

“…(1) and (2) generally increases with increasing basicity in the lime-based silicate, aluminate, and aluminosilicate melts with and without fluorspar, 6,8,[10][11][12][13][14] whilst there are some experimental results for an increase in the carbon solubility as the content of acidic oxides (SiO 2 and B 2 O 3 ) increases. 8,10,15,16) ......... (1) .......... (2) where K (1) , a i , f C 2 2Ϫ, and p O 2 are, respectively, the equilibrium constant of Eq. (1), the activity of i, the activity coefficient of carbide ions, and the oxygen partial pressure.…”

“…Even though there are some experimental results for the solubility of carbon in the lime-based slags, [5][6][7][8][9][10][11][12][13][14][15][16] the carbide capacity of the MnO-containing slag is hardly found. The only system containing MnO in view of carbon solubility is the BaO-MnO flux, where the carbon solubility increased with increasing content of BaO not only due to a basic characteristic of BaO but also due to a strong ionic attrac- The carbide capacity of the CaO-SiO 2 -MnO slag, which is the main system produced during Mn alloys processes, through the wide composition region has been measured at 1 773 K to understand the effective slag composition on the solubility of carbon in molten slags during SiMn production processes.…”

“…Also, the relationship between carbide capacity, log C C 2 2Ϫ and optical basicity in the CaO-SiO 2 -MnO slag is reasonably close to that of CaO-Al 2 O 3 -CaF 2 and CaO-SiO 2 -CaF 2 -Na 2 O slags. 14,15) It is meaningful to discuss the relationship between carbide and sulfide capacities of the slag in view of the basicity difference and the relative stability of each reaction product. 29) A relationship between sulfide capacity and carbide capacity of various slags is shown in Fig.…”

Effect of Atmosphere and Slag Composition on the Evolution of PH3 Gas during Cooling of Reducing Dephosphorization Slags

“…However, the distribution ratio of phosphorous remained constant at CaO content greater than about 20 mass%, where the flux is saturated by solid lime from the CaO-CaF2 binary phase diagram, 20) indicating that the activity of free O 2-ions is approximately constant, assuming that is proportional to aCaO in the flux. [21][22][23][24][25][26][27][28] …”

Effect of ZrO<SUB>2</SUB> Addition to the CaO-SiO<SUB>2</SUB>-MgO-CaF<SUB>2</SUB> Slags on the Sulfur Removal from the 16Cr-14Ni Stainless Steel Melts

“…11,12) The sulfide capacity of the slags is shown in Fig. 11 as a function of the activity of CaO in the liquid phase, which was calculated by using FactSage5.4Ô at 1873 K in logarithmic scale.…”