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Rate and Mechanism of Reduction-Dissolution of Chromite in Liquid Slags

机译：铬铁矿在液渣中还原溶解的速率及其机理

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摘要

The dissolution of chromite from the Bushveld Complex of South Africa in liquid slags was studied in the temperature range 1550° to 1665℃ under argon gas. The slag compositions were similar to those of ferrochromium production and stainless steel making. Empirical relations between the slag composition and the dissolution of chromite were established through the use of a statistical model. The dissolution process was investigated by using the rotating cylinder technique and measured by the chemical analysis of the samples taken from the melt and the SEM-EDAX analysis of the reacted chromite cylinder samples. The chromite grains were depleted in iron and chromium as the dissolution progressed, leaving behind an alumina and magnesia rich spinel. The experimental data was evaluated by using kinetic models and mass transfer coefficients of chromium, iron and oxygen ions through the phase boundary between the solid chromite cylinder and the liquid slag were determined. The dissolution of chromite in liquid slags increases with increasing stirring rate. SEM-EDAX studies on the reacted chromite cylinders showed that coring took place within the chromite grains subjected to dissolution for sufficient length of time. Chromium and iron concentrations in the chromite were decreasing from the centre towards the surface of the grains while aluminum and magnesium contents were increasing at the edges compared to the centre of the chromite grains. Furthermore, the slag rich in alumina and magnesia diffuses in bulk into the chromite with a net result of increase in the concentration of these elements. The rate of dissolution of chromite in liquid slags was found to be controlled by the mass transfer of oxygen ions (O~(2-)) through the liquid phase boundary between the solid chromite and the liquid slag. The activation energy for the mass transfer of O~(2-) ions was calculated as 30.61 kCal/mol (128.07 kJ/mol).
机译：研究了在氩气作用下，在1550°至1665℃温度范围内，南非布什维尔德络合物中铬铁矿在液渣中的溶解情况。炉渣的组成类似于铬铁生产和不锈钢制造。通过使用统计模型，建立了炉渣成分与铬铁矿溶解之间的经验关系。通过使用旋转圆筒技术研究溶解过程，并通过对从熔体中取出的样品进行化学分析和对已反应的铬铁矿圆筒样品进行SEM-EDAX分析进行测量。随着溶解的进行，亚铬铁矿中的铁和铬被消耗掉，留下了富含氧化铝和氧化镁的尖晶石。利用动力学模型对实验数据进行了评估，并确定了铬，铁和氧离子通过固态亚铬酸盐圆柱体和液态渣之间的相界的传质系数。随着搅拌速度的增加，铬铁矿在液态炉渣中的溶解度增加。 SEM-EDAX对反应过的铬铁矿圆柱体的研究表明，在经过足够长的时间溶解的铬铁矿晶粒内发生了取芯。与铬铁矿晶粒的中心相比，铬铁矿中铬和铁的浓度从晶粒的中心向表面降低，而铝和镁的含量在边缘增加。此外，富含氧化铝和氧化镁的炉渣大量扩散到铬铁矿中，最终增加了这些元素的浓度。发现铬铁矿在液态炉渣中的溶解速率受氧离子（O〜（2-））通过固态铬铁矿和液态炉渣之间液相边界的传质控制。 O〜（2-）离子传质的活化能为30.61 kCal / mol（128.07 kJ / mol）。

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  • 来源
    《High temperature materials and processes》 |2013年第3期|255-263|共9页
  • 作者

    Orhan Demir; Rauf Hurman Eric;

  • 作者单位

    Tenova-Pyromet, Johannesburg, South Africa;

    School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Johannesburg, South Africa;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    rate; mechanism; chromite; dissolution; slag;

    机译：率;机制;铬铁矿;解散矿渣;

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