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摘要: 結合CO2的高溫反應特性,針對性地制定了CO2冶煉工藝,并對轉爐頂吹CO2比例對終點磷、氮和碳氧濃度積的影響進行了工業試驗研究。結果表明:隨著轉爐冶煉前中期CO2頂吹比例由4.84%逐漸提高到9.68%,轉爐終點磷的質量分數先下降后基本不變,氮的質量分數逐漸下降,碳氧濃度積與渣中TFe變化趨勢基本相同,均為先降低后增加,對于不同指標最佳頂吹CO2比例不同。試驗轉爐終點磷、氮的質量分數、碳氧濃度積與渣中TFe均下降,下降比例最高分別為20.4%、34.3%、12.92%和8.89%。Abstract: When combined with the high-temperature reaction characteristics of carbon dioxide—that is, the weak oxidation, endothermic, or weak exothermic effect compared with oxygen and the bubble increment effect of reacting with carbon to produce twice the gas—the carbon dioxide smelting process was targeted according to the different tasks in different periods of converter smelting. Before temperature measurement, sampling, and carbon determination using the sublance system, carbon dioxide is blown into the converter from the upper oxygen gun and the bottom blowing element of the converter. By changing the ratio of carbon dioxide and oxygen in the oxygen gun, an industrial experimental study was conducted on the effect of the carbon dioxide ratio blown from the upper oxygen gun on the endpoint of the mass fraction of phosphorus and nitrogen and the carbon–oxygen concentration product. The results show that with the gradual increase of the carbon dioxide top blowing ratio from 4.84% to 9.68% in the early and middle stages of converter smelting, the mass fraction of phosphorus at the end of the converter first decreases and then basically remains unchanged. The mass fraction of nitrogen also decreases gradually, but the decreasing range becomes smaller, and the changing trend of carbon–oxygen concentration product is the same as that of TFe in slag, which first decreases and then increases. The optimal carbon dioxide top-blowing ratio varies with the index. Furthermore, the test also shows that even if all the blown carbon dioxide reacts to generate additional carbon monoxide gas and the nitrogen is removed by the additional carbon monoxide gas generated compared with the original process, the partial pressure of nitrogen in the additional gas is much higher than the partial pressure in equilibrium with the mass fraction of nitrogen in the liquid steel. This indicates that the improvement of the denitrification effect is due to the additional gas generated by the reaction of blowing in carbon dioxide; it improves the denitrification effect of the original gas, and the generation of additional gas improves the kinetic conditions of the molten pool and facilitates the mass transfer of nitrogen. The highest decreasing ratio of the endpoint mass fraction of phosphorus, nitrogen, carbon–oxygen concentration product, and TFe in the slag of the test converter was 20.4%, 34.3%, 12.92%, and 8.89%, respectively.
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表 1 CO2與鋼液中元素反應的熱力學數據[19]
Table 1. Thermodynamic data of reactions between CO2 and elements in molten steel[19]
Element Reaction equation $\Delta {G^{\circleddash} }$/(J·mol?1) T=1873 K,
$\Delta {G^{\circleddash} }$/(kJ·mol?1)C 1/2O2 + [C]=CO(g) ?140580?42.09T ?219.41 O2 + [C]=CO2(g) ?419050+42.34T ?339.75 CO2(g) + [C]=2CO(g) 137890?126.52T ?99.08 Fe 1/2O2(g) + Fe(l)=(FeO) ?229490+43.81T ?147.43 CO2(g) + Fe(l)=
(FeO)+CO(g)48980?40.62T ?27.10 Si O2 + [Si]=(SiO2) ?804880+210.04T ?411.48 2CO2(g) + [Si]=
(SiO2)+2CO(g)?247940+41.18T ?170.81 Mn 1/2O2 + [Mn]=(MnO) ?412230+126.94T ?174.47 CO2(g) + [Mn]=
(MnO)+CO(g)?133760+42.51T ?54.14 P 4/5[P] + O2(g) =
2/5P2O5(g)?375040+134.23T ?123.63 2/5[P]+CO2(g)=
1/5(P2O5)+CO(g)91555?16.86T 59.98 表 2 工業試驗方案
Table 2. Industrial test scheme
Scheme Stage Top blowing O2 (standard status) /(m3·h?1) Top blowing CO2 (standard status) /(m3·h?1) Top blowing
CO2 ratio/%Bottom blowing CO2/Ar (standard status) /(m3·h?1) Original process Early and middle stage 62000 0 0 800/0 Later stage 62000 0 0 0/1200 Test 1 Early and middle stage 59000 3000 4.84 800/0 Later stage 62000 0 0 0/1200 Test 2 Early and middle stage 58000 4000 6.45 800/0 Later stage 62000 0 0 0/1200 Test 3 Early and middle stage 57000 5000 8.06 800/0 Later stage 62000 0 0 0/1200 Test 4 Early and middle stage 56000 6000 9.68 800/0 Later stage 62000 0 0 0/1200 Note: the early and middle stage, in the top blowing refers to the stage before TSC, and in the bottom blowing refers to the stage when the top blowing oxygen supply is less than 9000 m3 (standard status); the later stage, in the top blowing refers to the stage after the TSC, in the bottom blowing refers to the stage when the top blowing oxygen supply is greater than 9000 m3 (standard status). Top blowing means that the converter injects O2 and CO2 through the oxygen gun, bottom blowing means that the converter injects Ar or CO2 through the bottom blowing element, and TSC means that the converter measures temperature and samples carbon through the auxiliary gun. 表 3 試驗碳、溫度與補熱劑加入情況
Table 3. Industrial test carbon, temperature, and heat compensating material
Scheme Element mass fraction of molten iron/% Mass fraction of end carbon/% Endpoint temperature/ ℃ Heat compensating material (per ton)/kg Number of furnaces C Si Mn P Ferrosilicon Coke High efficiency heat compensating material Original process 4.30 0.29 0.11 0.069 0.0361 1651.8 1.127 0.644 2.672 85 Test 1 4.31 0.29 0.10 0.068 0.0377 1649.7 1.821 1.597 3.577 47 Test 2 4.36 0.29 0.10 0.071 0.0359 1653.1 2.138 0.893 1.308 116 Test 3 4.36 0.29 0.11 0.073 0.0360 1656.2 1.044 0.981 1.424 269 Test 4 4.30 0.28 0.12 0.072 0.0369 1658.3 2.361 1.279 2.557 127 www.77susu.com -
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