Study on the behavior of unburnt pulverized coal and reduction productions of TiO2 in high-titanium blast furnace slag
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摘要: 采用旋转柱体法对配加未燃煤粉的高钛型高炉渣的黏度进行了测量,结合试验样品的宏观形貌和不同部位微观结构的表征,对未燃煤粉及其还原产物在高钛型高炉渣中的行为进行了分析。结果表明,未燃煤粉不可避免地会与渣中TiO2反应,残余的未燃煤粉及其还原产物,如Ti(C,N)或TiCxOy等高熔点物相不均匀分布于渣中。随着初始未燃煤粉含量从0增加至5.51%,渣中TiC和TiN含量之和从0.456%升高至2.515%,反应生成的高熔点物质向下沉降聚集,残余的未燃煤粉则向上运动,与上部炉渣中的TiO2继续反应生成高熔点物质或形成泡沫渣,并导致炉渣黏度显著升高,波动显著加剧,炉渣中部则几乎没有残余未燃煤粉和高熔点还原产物。Abstract: In this study, the viscosity of high-titanium blast furnace slags uniformly mixed with unburnt pulverized coal (UPC) was measured by using the method of rotating cylinder firstly. Then the distribution and behavior of the residual UPC and the reduction products were analyzed according to the macro morphology of these samples and their microscopic morphology of different parts. It was found that TiO2 would inevitably be reduced by UPC, the high melting point reduction products such as Ti(C,N), TiCxOy and unburnt UPC distributed nonuniformly in the slag. As the initial UPC content increased from 0% to 5.51%, the total content of TiC and TiN increased from 0.456% to 2.515%. The high melting point reduction products deposited downwards and aggregated, while the unburnt UPC floated upwards and continued to react with TiO2 to form foam slag, resulting in a significant increase in both viscosity and its fluctuation. However, there were negligible residual unburnt UPC and high melting point reduction products in the middle of the slag.
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表 1 喷吹煤粉和未燃烧煤粉的化学成分
Table 1. Chemical compositions of PCI and UPC
% 名称 Cad Vdaf Ad St 灰分分析 CaO SiO2 MgO Al2O3 Fe2O3 TiO2 K2O Na2O 喷吹煤粉 80.60 9.78 11.74 0.78 1.88 49.51 0.44 38.13 3.90 1.18 0.722 1.32 未燃煤粉 88.70 0.17 11.97 0.48 2.10 50.54 0.54 37.65 3.36 1.38 0.66 1.13 表 2 基准高炉渣化学成分
Table 2. Chemical composition of on-site blast furnace slag
% CaO SiO2 MgO Al2O3 MnO FeO TiO2 Ti2O3 TiO TiC TiN 26.46 25.52 8.40 13.70 0.63 1.03 21.20 0.897 0.504 0.100 0.356 表 3 炉渣未燃煤粉配加方案
Table 3. Adding scheme of UPC to slag
编号 燃烧率/% 炉渣质量/g 未燃煤粉质量/g 未燃煤粉含量/% M0 100 170.00 0 0 M1 90 168.04 1.96 1.15 M2 80 166.12 3.88 2.28 M3 70 164.25 5.75 3.38 M4 60 162.42 7.58 4.46 M5 50 160.63 9.37 5.51 表 4 残余未燃煤粉的质量和C含量
Table 4. The mass and C contents of unconsumed UPC
编号 质量/g C/% M1 0.87 84.40 M2 2.77 84.80 M3 4.00 85.80 M4 6.82 86.00 M5 7.50 86.90 表 5 不同样品的低价钛化合物含量
Table 5. Mass fractions of different titanium compounds of slags after viscosity measurements
% 编号 TiO2 Ti2O3 TiO TiC TiN M0 21.20 0.897 0.504 0.100 0.356 M1 21.43 2.570 0.955 0.905 0.681 M2 21.64 2.570 1.050 1.110 0.727 M3 21.55 2.270 1.250 1.360 0.681 M4 21.19 0.247 1.910 1.730 0.526 M5 21.24 0.648 1.880 2.190 0.325 表 6 RO、RC和RTCN的计算结果
Table 6. The calculation results of RO, RC and RTCN
编号 Oloss/g ${\mathrm{O}}_{{\mathrm{TiO}}_2} $/g RO/% Ccoms/g CUPC/g RC/% TiTiCN/g ${\mathrm{Ti}}_{{\mathrm{TiO}}_2} $/g RTCN/% M1 2.28 14.40 15.85 1.392 1.74 80.08 2.10 21.61 9.73 M2 2.52 14.38 17.51 1.633 3.44 47.44 2.41 21.57 11.17 M3 2.70 14.16 19.04 1.845 5.10 36.17 2.65 21.24 12.49 M4 2.76 13.77 20.05 2.008 6.72 29.86 2.91 20.65 14.09 M5 3.02 13.65 22.10 2.342 8.31 28.18 3.22 20.47 15.72 表 7 RO、RC和RTCN的拟合结果
Table 7. The calculation results of RO, RC and RTCN
equation a b c Adj. R2 RO y = a + bx 14.28 1.38 0.988 RTCN y = a + bx 8.05 1.37 0.996 RC y = aexp(-x/b) + c 136.27 1.23 26.70 0.999 -
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