Distribution of alkali compunds in a large blast furnace

The Quantitative Effect of Blast Furnace Slag Composition and Temperature on the Kinetics of Potassium Evaporation

“…From material balances, the introduction of alkalis in the top-charged materials is mainly attributed to the ferrous burden. [1,2] However, Sukarovs et al [3] characterized a range of coke samples, finding that the alkali content varied between 0.11 and 0.30 wt pct, which suggests the possibility of significant contributions from the coke ash as well. Previously published material balances recognized the contribution of coke, presenting that the coke ash may account for as much as 22 to 56 pct of the total alkali load in the BF.…”

“…However, significantly higher alkali loads have been reported in commercial operation, e.g., publications with figures varying between 6.5 and 14 kg alkalis/tHM exist. [1,2,[6][7][8][9] In addition, Lu [10] reported on declining qualities regarding the chemical composition of fine iron ore products and stated that the trend for continued downshift in iron ore quality is expected ANTON for the future. Similar observations have been reported, but specifically for the alkali content, in other publications as well.…”

“…Due to the detrimental effects of high alkali loads in the BF, several strategies have been proposed and employed in order to mitigate accumulation in the BF. These strategies include (i) lowering the input of alkalis, [1,2,4,8,12,[20][21][22] (ii) maximizing the quality of sinter and coke, [20] (iii) charging coarse dunite as an alkali removal agent, [28] (iv) increasing the slag rate, [17,21] and (v) altering the slag composition. [4,[7][8][9]17,[19][20][21][22]29] In addition, less realistic suggestions for modern BF ironmaking have been proposed and operated, such as charging CaCl 2 as an alkali cleaner [20][21][22] and reducing in-plant recycling via the sinter.…”

“…[2,7,17,19] However, cases of 20-78 pct removal via the slag exist. [1,[20][21][22] Considering these variations in the efficiency of utilizing the slag phase as the outlet of alkalis, the effect of altering the slag composition on the alkali capacity of the slag is of great interest to understand. Furthermore, Ivanov et al [30] discussed that maximizing alkali output via the slag is favorable over alkali loading in the BF dust.…”

“…[33] The main findings can be summarized as K 2 O content in the slag decreases with increasing B3 basicity (Eq. [1]). Furthermore, at constant B3 basicity with an increasing amount of MgO, the equilibrium K 2 O content in the slags increased.…”