高硫精矿配比对烧结矿性能的影响

 相比进口富矿粉,精矿品位较高,可广泛应用于铁矿石烧结工序。为了探究高硫精矿对烧结矿产质量的影响以及精矿中硫元素对烧结过程的影响,利用烧结杯试验装置进行了高硫精矿配比在25%~45%范围内的烧结杯试验。并通过微观结构、技术指标及冶金性能等方面表征了高硫精矿配比对烧结矿性能的影响。试验结果表明,精矿配比为25%时,烧结矿还原的界面反应条件较差,硅酸盐相阻碍了还原气体的扩散,致使烧结矿还原度为77.80%,软化开始温度为1 200 ℃,软熔带透气性能恶化。精矿配比为30%时,烧结利用系数提升至1.19 t/(m2·h)、垂直烧结速度达到22.22 mm/min。精矿配比为40%时,有效改善了烧结矿还原性能,恶化了低温还原粉化性能。精矿配比为45%时,烧结利用系数最高,为1.20 t/(m2·h),还原性能和低温还原粉化性能适宜。整体而言,在试验范围内,适当增加高硫精矿配比有利于提升烧结矿的还原性能和荷重软化熔滴性能,但精矿配比为45%时烧结矿的熔滴S特性值为281.02 kPa·℃,透气性能恶化。烧结烟气方面,精矿配比为40%时,烧结烟气的CO₂和NO_x含量较高,烧结过程氧化性气氛较强,降低了烧结矿中铁橄榄石等低还原性矿物含量,恶化了低温还原性能。烟气分析结果表明,高硫精矿烧结时硫元素基本都进入烧结烟气中,并未恶化烧结矿性能。

Effect of high-sulfur concentrate on properties of sinter

Concentrate is widely used in iron ore sintering process because its higher grade than that of imported ore-rich powder. However, there are few studies about the effect of high-sulfur concentrate on properties of sinter. Therefore, in order to study the effects of high-sulfur concentrate on the properties of sinter and influence of S element in concentrate on sintering process, a series of sinter cup experiments with high-sulfur concentrate concentration of 25%-45% were carried out, and the influences were characterized through microstructure, sintering indices, and metallurgical properties. The experimental results showed that when the concentration of concentrates was 25%, the interface reaction conditions of reduction were poor, and the diffusion of reduction gas were hindered by silicate phase. This resulted in a lower reduction index with 77.80%, the initial softening temperature was 1 200 ℃, and the permeability of cohesive zone deteriorated. The concentrates with 30% increased the sintering utilization index to 1.19 t/(m2·h), and improved vertical sintering speed to 22.22 mm/min. The sinter with high-sulfur concentrate concentration of 40% had improved reduction property and deteriorated the low temperature reduction degradation property. When the concentration was 45%, the sintering utilization index was the highest with 1.20 t/(m2·h), the reduction performance and reduction degradation property were suitable. On the whole, an appropriate increase in high-sulfur concentrate content was beneficial to improve the reduction performance and softening-melting performance of the sinter, but when the concentrate ratio was 45%, the S-value was 281.02 kPa·℃, meaning poor permeability performance of sinter. In the terms of sintering flue gas, when concentration of concentrates was 40%, the CO₂ and NO_x content of sintering flue gas were high, showing a high oxidizing atmosphere in the sintering process, which decreased the content of low-reducibility minerals such as iron olivine in the sinter and deteriorated the reduction degradation index. The results of flue gas analysis showed that the S element of high-sulfur concentrate basically entered sintering flue gas during sintering process, and the performance of sinter was not deteriorated.