难选褐铁矿磁化焙烧空气冷却技术研究

    Study on air cooling process for limonite magnetization roasting

    • 摘要: 悬浮磁化焙烧作为一种处理复杂难选铁矿的技术手段,对于难选褐铁矿资源的开发利用具有重大意义。为探究褐铁矿磁化焙烧空气冷却技术的可行性,本文以昆钢包子铺褐铁矿为研究对象,进行了磁化焙烧及空气冷却试验研究。通过系统的条件试验,确定了褐铁矿在还原温度580 ℃、焙烧时间5 min、H2浓度30%条件下可以得到较好的磁化效果,焙烧矿经N2保护冷却后的磁选精矿铁品位57.92%,回收率87.94%。对焙烧矿进行了空气冷却技术研究,探究了空气气氛下氧化时间、氧化温度对磁铁矿氧化过程的影响规律。研究结果表明,在氧化温度300 ℃、氧化时间3 min时磁铁矿基本全部被氧化,冷却样品以强磁性的磁赤铁矿为主,含有少量的弱磁性的赤铁矿,此后,随着氧化时间与氧化温度的增加,赤铁矿含量开始增加,磁赤铁矿的含量降低,但仍以强磁性的磁赤铁矿为主,通过对氧化条件的合理控制可以维持空气氧化产品的磁赤铁矿的主导地位,确保冷却产品的磁性。本研究为复杂难选褐铁矿资源的高效利用提供了可行的技术方案,对促进低品位的铁矿资源的开发具有重要意义。

       

      Abstract: As an effective technical approach for processing complex and refractory iron ores, Suspension magnetization roasting is of great significance for the efficient utilization of difficult-to-process limonite resources. To investigate the feasibility of magnetization roasting followed by air cooling for limonite, systematic experiments are conducted using the Baozipu limonite from Kunming Iron and Steel as the research subject. Through systematic condition-specific experiments, optimal magnetization conditions for limonite are established at a reduction temperature of 580 ℃, roasting duration of 5 minutes, and H2 concentration of 30%. The magnetically separated concentrate obtained after nitrogen-protected cooling achieved an iron grade of 57.92% with a recovery rate of 87.94%. Further research is carried out on the air cooling process of the roasted ore, with particular attention being paid to the influence of oxidation time and temperature on the oxidation behavior of magnetite in an air atmosphere. The results reveal that at an oxidation temperature of 300 ℃ for 3 min, magnetite is almost completely oxidized, with the cooles product being predominantly composed of strongly magnetic maghemite and a minor amount of weakly magnetic hematite. With prolonged oxidation time or increased temperature, the hematite content is observed to gradually rise while the maghemite content decreased, though maghemite is maintained as the dominant phase. By controlling the oxidation conditions, the dominance of maghemite in the air-cooled product could be maintained, thus ensuring favorable magnetic properties. The findings are considered to provide a viable technical solution for the efficient utilization of complex and low-grade limonite resources, contributing to the sustainable development of refractory iron ore reserves.

       

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