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首页> 外文期刊>Journal Of The South African Institute Of Mining & Metallurgy >Reduction of Kemi chromite with methane
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Reduction of Kemi chromite with methane

机译：用甲烷还原kemi铬铁矿

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Kemi chromite ore from Finland was reduced in CH4-H2 gas mixtures at temperatures from 1100° to 1350°C. Experimental variables were time, temperature, and the CH4 content of the gas mixture. The phases in reacted samples were determined by XRD and quantitative phase analysis was performed using the Rietveld method. Particle morphology and phase compositions were determined using SEM and EDS analysis. Reduction proceeded through a shrinking core model in two stages. In the first stage, hydrogen and carbon from the cracking of methane reduced the iron and some chromium to carbides. The chromium in the remaining spinel was reduced during the second stage. Iron was essentially reduced in full after 30 minutes when the temperature reached 1300°C, and at 1350°C it was completely reduced within 20 minutes. At this highest temperature, all of the chromium was eventually reduced, the residue consisting of aluminum and magnesium oxides with varying amounts of silica. At the surface of the particle iron and chromium, together with carbon, formed two alloys, an iron-dominated and a chromium-based one. The iron-based phase was partially molten at the higher temperatures. At 1300°C and 1350°C the metallization was complete. Reduction of Kemi chromite with a CH4-H2 mixture is judged as highly efficient, since high of reduction extents could be reached faster at lower temperatures compared to carbothermic reduction. This is attributed to the very high activity of carbon (way above 1.0) due to the cracking of methane into hydrogen and carbon at around 550°C in the presence of a solid phase.
机译：来自芬兰的Kemi Chromite Oree在1100°至1350℃的温度下在CH 4-H 2气体混合物中减少。实验变量是时间，温度和气体混合物的CH 4含量。通过XRD测定反应样品中的相位，并使用RIETVELD方法进行定量相分析。使用SEM和EDS分析测定颗粒形态和相组合物。减少通过两个阶段的缩小核心模型进行。在第一阶段，来自甲烷的裂化的氢和碳将铁和一些铬的碳水化合物还原为碳化物。在第二阶段期间剩余尖晶石中的铬减少。当温度达到1300℃时30分钟后，铁在30分钟后完全减少，在1350℃下，在20分钟内完全降低。在这种最高温度下，最终均最终降低，残留物由具有不同量二氧化硅的铝和氧化镁组成。在颗粒铁和铬的表面上，与碳，形成两个合金，铸铁和铬基。在较高温度下部分熔化铁基相。在1300°C和1350℃下，金属化完成。用CH 4 -H 2混合物还原kemi铬铁矿被判断为高效，因为与碳热还原相比，可以在较低温度下达到高度的减少范围。这归因于由于甲烷在固相存在下甲烷到氢气和碳在约550℃的碳中的碳和碳的裂化而非常高的碳（以上方式）。

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