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某些高品位铁精矿球团在用气体(H_2或CO或其混合物)还原时发生所谓的灾难性膨胀的问题,早已多有报道.以钒钛磁铁矿为原料的球团的还原膨胀性质的研究尚未进行过.为解决钒钛磁铁矿球团竖炉直接还原过程中发生的灾难性膨胀问题,在实验室中用光学投影法研究了氧化钠化球团还原时的特性.不附加任何添加剂的氧化球团(TY)升温还原到550～750℃时发生正常膨胀,最大线膨胀率为4～7%.添加5～6%芒硝的氧化球团(6NTY)在同样条件下发生灾难性膨胀,最大线膨胀率15～30%,膨胀后的球团严重粉化,一触即溃.但6NTY球团在高于～1100℃恒温还原时,仅作正常膨胀.用控制气体还原位的方法分步还原实验结果表明,6NTY球团的灾难性膨胀及TY球团的正常膨胀都是发生在赤铁矿-磁铁矿转变阶段,这与国外研究者提出的在浮土体-金属铁阶段生成的铁须导致球叫灾难灶膨胀的观点不同.用弱还原性气氛(例如CO/CO_2=1/99的还原气体)对球团作磁铁矿化处理,消除了赤铁矿,从而完全消除了灾难性膨胀.磁铁矿化球团(6NTM, 6NTYM, 6NTYVM)的还原膨胀值仅～1.5%,相当于球团的热膨胀值.提出了磁铁矿化指标α=Fe~(3+)/TFe-0.70TiO_2作为事先检验球团还原膨胀性质的判据.研究结论已为四川省冶金研究所进行的扩大试验结果所证实.
The problem of so-called catastrophic swelling of some high-grade iron ore pellets when they are reduced with gas (H 2 or CO or mixtures thereof) has long been reported. The reduction and expansion of pellets made from vanadium-titanium magnetite Nature has not been studied.In order to solve the problem of disastrous expansion during the direct reduction of vanadium-titanium magnetite pellet shaft furnace, the characteristics of reduction of sodium oxide pellets were studied by optical projection method in laboratory Oxidation pellets (TY) with any additives added were heated to a temperature of 550-750 ° C and expanded normally with a maximum linear expansion of 4-7%. Oxidation pellets (6NTY) with 5 ~ 6% mirabilite occurred under the same conditions Catastrophic expansion, the maximum linear expansion rate of 15 to 30%, after the expansion of the pellet serious chalking, touch that collapse, but the 6NTY pellet at higher than ~ 1100 ℃ constant temperature reduction, only for normal expansion with the control gas reduction method The experimental results show that the catastrophic expansion of 6NTY pellets and the normal expansion of the TY pellets all occur during the transformation of hematite-magnetite. This is in agreement with the results from foreign researchers in the stage of floating soil-metal iron Iron skewers lead to the ball called a disaster stove expansion point of view not . Magnetising the pellets with a weak reducing atmosphere (for example, a reducing gas of CO / CO 2 = 1/99) eliminates hematite and completely eliminates catastrophic expansion. The magnetite pellets ( 6NTM, 6NTYM and 6NTYVM) is only ~ 1.5%, which is equivalent to the thermal expansion of the pellets. The magnetite mineralization index α = Fe ~ (3 +) / TFe-0.70TiO_2 Nature of the criteria.The conclusions of the study have been confirmed by the results of the expansion test conducted by the Sichuan Institute of Metallurgy.