Research and application of improving the compressive strength of full V-Ti pellets
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摘要: 针对全钒钛球团矿抗压强度低（平均1 600 N/个左右）、波动大（最低仅926 N/个，最高2 287 N/个），进入高炉冶炼后极大的影响了高炉稳定顺行，特开展了提高全钒钛球团矿抗压强度技术研究与应用。结果表明：通过增设润磨设备后，造球混合料粒度小于0.074 mm粒级由66.64%提高至71.69%，矿物颗粒表面变粗糙，粘结性增加，活性增强；且将预热二段温度提高到900 ℃左右、降低链篦机机速、延长预热时间，将焙烧温度从1150 ℃提高至1200 ℃以上，降低回转窑转速，延长焙烧时间后，球团矿内部带直径降低至3 mm以下，抗压强度提高至1 989 N/个，波动明显减小，为高炉稳定顺行提供了原料基础。Abstract: The low compressive strength (average 1 600 N/P) and large strength fluctuation (926 N/P min, 2287 N/P max) of V-Ti pellets greatly affect the stability and smooth operation of blast furnace after being smelted in blast furnace. The technical research and application of improving the compressive strength of full V-Ti pellets have been carried out. After utilizing wet grinding equipment, the proportion of pelletizing mixture less than 0.074 mm is increased from 66.64% to 71.69%. And the surface of mineral particles becomes rough. Besides, the cohesiveness and activity increases as result of installing wet grinding equipment. By increasing the temperature of second preheating stage to about 900 ℃ and reducing the grate speed to prolong the preheating time, at the same time increasing the roasting temperature from 1 150 ℃ to more than 1 200 ℃ and reducing the rotary kiln speed to prolong the roasting time, the diameter of inner zone of pellet can be reduced to less than 3 mm, and the compressive strength is increased to 1 989 N/P and its fluctuation become narrow.
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Key words:
- V-Ti pellet /
- compressive strength /
- roasting temperature /
- microstructure
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图 1 润磨前后混合料颗粒形貌
(a)润磨前； (b)润磨后
Figure 1. Particle morphology of mixture before and after wet grinding
图 2 润磨时间对生球落下强度和抗压强度的影响
Figure 2. Effect of wet grinding time on wet knock and strength of green pellet
图 3 预热温度和预热时间对球团氧化率的影响规律
Figure 3. Effect of preheating temperature and time on pellet oxidation rate
图 4 预热温度和预热时间对球团抗压强度的影响规律
Figure 4. Effect of preheating temperature and time on pellet strength
图 5 焙烧温度对球团抗压强度和FeO含量的影响规律
Figure 5. Effect of roasting temperature on strength and FeO content of pellet
图 6 焙烧时间对球团抗压强度和FeO含量的影响规律
Figure 6. Effect of roasting time on strength and FeO content of pellet
图 8 全钒钛球团内部带和外部带的微观形貌
a-内部带；b-外部带P—孔；S—硅酸盐相；L—钛铁矿；H—赤铁矿
Figure 8. Micro-morphology of the inner and outer band
图 9 工业应用前后抗压强度变化情况
Figure 9. Changes of compressive strength of pellet before and after technology optimization
表 1 钒钛磁铁矿样品的主要化学成分及烧损
Table 1. Main chemical composition and Ig of sample V-Ti magnetite
% TFe FeO SiO2 CaO V2O5 TiO2 MgO Al2O3 Ig 55.22 29.46 4.15 0.80 0.707 9.99 3.80 3.85 −1.40 注：Ig为烧损量。 
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表 2 钒钛磁铁矿样品的粒度组成
Table 2. Size distribution of sample V-Ti magnetite
% >0.15 mm 0.15～0.074 mm 0.074～0.045 mm <0.045 mm <0.074 mm 7.03 28.26 21.06 43.65 64.71
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表 3 膨润土的主要化学成分
Table 3. Main chemical composition of bentonite
% Fe2O3 SiO2 CaO Al2O3 MgO K2O Na2O Ig 3.22 55.00 4.82 14.03 3.42 0.98 1.52 14.69
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表 4 膨润土的物理性能
Table 4. Physical properties of bentonite
胶质价/
%膨胀容/
(mL·g−1)吸兰量(100 g计)/
gpH值 粒度<0.074 mm的
矿物含量/%62.00 42.02 35.70 10.44 97.79
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表 5 润磨时间对混合料粒度组成的影响
Table 5. Effect of wet grinding time on size distribution of mixture
润磨时间/min 粒度组成/% >0.15 mm 0.15～0.075 mm 0.074～0.045 mm <0.045 mm <0.074 mm 0 7.03 28.26 21.06 43.65 64.71 3 5.72 23.36 22.16 48.76 70.92 4 4.96 22.83 21.78 50.43 72.21 5 4.50 22.21 20.96 52.33 73.29 6 4.12 21.72 19.99 54.17 74.16
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表 6 不同焙烧温度的内部带直径
Table 6. Inner band diameter of pellet after roasting at different temperatures
焙烧温度/℃ 内部带直径/mm 1150 5～8 1180 4～5 1200 3～4 1250 1～2 1280 0～1
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表 7 链篦机-回转窑热工制度优化情况
Table 7. Optimization of grate kiln thermal system
项目 链篦机机速
/(m·min−1)预热一段
/℃预热二段
/℃回转窑转速
/(r·min−1)窑头温度
/℃窑中温度
/℃窑尾温度
/℃优化前 2.3 550～580 820～850 1.0 950～980 1150～1180 730～760 优化后 1.95 600～630 890～920 0.91 1070～1100 1220～1250 770～800
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