含钾、钠、氟铁矿石的高温性能及包钢合理炉料结构的研究

HIGH TEMPERATURE PROPERTIES OF SINTER CONTAINING K, Na, F AND OPTIMUM BF BURDEN

本文利用五因子二次回归正交设计法研究了K_2O、Na_2O、F、MgO和CaO/SiO_2对烧结矿高温性能的影响。K_2O、Na_2O和F的升高,使软熔性能严重恶化;F的存在使K_2O和Na_2O的不良影响加重了。提高CaO/SiO_2和MgO可以改善软熔性能,但其作用较普通烧结矿小。含K_2O、Na_2O和F的烧结矿在软熔过程中的压差陡升温度较普通烧结矿低200～250℃,使高炉内软熔带上升至热交换呆滞区,是料柱透气性恶化的主要原因。在精矿中K、Na、F不能显著降低的条件下,较优的入炉烧结矿成分是K_2O≤0.15%,Na_2O≤0.17%,F≤0.83%,MgO=2.5%,CaO/SiO_2=1.5;SiO_2≤6.5%。较合理的炉料结构是80%上述成分的烧结矿加上20%无钾、钠、氟的酸性球团。

The influence of K_2O, Na_2O, F, MgO and ratio CaO/SiO_2 in sinter on properties at high temperature was investigated by use of a quadratic regression orthogonal design of five factors. With increasing K_2O, Na_2O and F the softening-melting (SM) properties were strongly deteriorated. Presence of fluorine in sinter increases the undesirable effects of K_2O and Na_3O. Increasing the ratio CaO/SiO_2 and MgO content in this sinter will improve its SM properties, but the effect is smaller than that in sinter without K_2O, Na_2O and F. For sinter containing K_2O, Na_2O and F, the temperature ts at which the gas pressure drop increases suddenly is 200～250℃ lower than that for usual sinter. It will lift the cohesive zone into the thermal reserve zone in the blast furnace. This is an important factor which decreases the stock column permeability. if concentrates contain certain amounts of K_2O, Na_2O and F the suitable composition for sinter may be established as follows: K_2O≤0.15%; Na_2O≤0.17%; F≤0.83%; MgO=2.5%; CaO/SiO_2=1.5; SiO_2≤6.5%. The optimum burden should consist of 80% sinter with above mentioned composition and 20% acid MgO-contalning pellets without K, Na and F.