Metall. Res. Technol.
Volume 116, Number 4, 2019
|Number of page(s)||10|
|Published online||28 June 2019|
Study of CO2 injection on the desulfurization of low-titanium slag
School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing,
100083, PR China
2 HBIS Company Limited Chengde Branch, Chengde 067102, Hebei, PR China
3 National Engineering and Research Center of Continuous Casting Technology, Central Iron and Steel Research Institute, Beijing 100081, PR China
* e-mail: firstname.lastname@example.org
Accepted: 29 October 2018
A new idea that the low-titanium slag (LTS) used in the steelmaking process after CO2 injection desulfurization is proposed in this paper. The CO2 injection process mainly involves the grinding of low-titanium slag, mixing of slag and water, CO2 injection, filtration, and then obtains the low sulfur and low titanium slag. The effects of cooling rates (water cooling, air cooling, crucible cooling, and furnace cooling) and CO2 injection on the desulfurization of LTS were studied by both experimental and thermodynamic calculations. The results showed that sulfite and sulfate ions couldn’t be removed from LTS using this method, and the main removal substance in slag was sulfide ion S2−. The desulfurization mechanism with CO2 injection was that the CO2 injection reacted with H2O to form H2CO3, and then the H+ disrupted from H2CO3 reacted with the S2− in the slag to achieve desulfurization. During the desulfurization process, the desulfurization reaction was mainly determined by S2− + CO2 (aq) + H2O (l) = CO32− + H2S(g) within the first 5 min, and then the main desulfurization reaction was S2− + 2CO2 (aq) + 2H2O(l) = 2HCO3− + H2S(g). As the cooling rate decreasing, the desulfurization rate of LTS increased. The desulfurization effect of furnace-cooled slag is the highest in four kinds of slag. The desulfurization rate of furnace-cooled slag reaches 72.28%, which is 4.34, 1.75 and 1.15 times than that of water-cooled slag, air-cooled slag and crucible-cooled slag, respectively. The optimal rate of desulfurization is 80.0%.
Key words: low-titanium slag / CO2 injection method / cooling method / desulfurization mechanism / mixed liquor pH
© EDP Sciences, 2019
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