Thermal behaviors and growth of reduced ferronickel particles in carbon-laterite composites
Thermal behaviors and growth of reduced ferronickel particles in carbon-laterite composites
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DOI：
10.1007/s12598-011-0449-4
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发表时间：
2011-12
期刊：
影响因子：
8.8
通讯作者：
Donghua Huang;Jianliang Zhang;R. Mao;Ming-ming Cao
中科院分区：
文献类型：
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作者：
Donghua Huang;Jianliang Zhang;R. Mao;Ming-ming Cao
采用热重法（TG）、微分热重法（DTG）和差热分析法（DTA）研究了单一红土矿和石墨-红土矿混合物的热行为。观察到红土矿在约78、272、583和826°C下的四个最大质量损失步骤，分别代表游离水的蒸发、针铁矿的脱羟基、蛇纹石的分解和蛇纹石的第二脱羟基。石墨-红土混合物的还原反应在700°C左右开始，可以分为三个主要的温度区域。添加10 wt.%的煤-红土复合材料CaO在1100-1350°C下焙烧30 min，还原后的样品用X射线衍射（XRD）和扫描电镜（SEM）进行表征。结果表明，在较高的温度下，还原反应进行得更完全。焙烧温度对还原镍铁颗粒的生长有很大影响。在1250°C还原的样品中，还原后的镍铁颗粒明显长大，形成蠕虫状晶体，在1300°C还原的样品中，观察到球状颗粒。当还原温度升高至1350°C时，还原的镍铁颗粒附聚成直径为3-8 mm的镍铁颗粒。颗粒中的主要元素包括铁、镍、铬、碳和硫，其中镍和铁的含量为9.08wt.%和85.21重量%，分别
The thermal behaviors of single laterite ore and graphite-laterite mixtures were investigated by thermogravimetry (TG), derivative thermogravimetry (DTG), and differential thermal analysis (DTA). Four mass loss steps maximized at about 78, 272, 583, and 826°C are observed for the laterite ore, representing the vaporization of free water, the dehydroxylation of goethite, the decomposition of serpentines, and the second dehydroxylation of serpentines, respectively. The reduction reactions of the graphite-laterite mixtures start at around 700°C and can be divided into three major temperature regions. Coal-laterite composites with an addition of 10 wt.% CaO were roasted at 1100–1350°C for 30 min, and the reduced samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicate that the reduction reactions proceed more completely at higher temperatures. The growth of the reduced ferronickel particles is greatly influenced by the roasting temperature. Obvious growth of the reduced ferronickel particles appears with the formation of worm-like crystals for the sample reduced at 1250°C, and spheric particles are observed for the sample reduced at 1300°C. When the reduction temperature increases to 1350°C, the reduced ferronickel particles agglomerate to ferronickel granules of 3–8 mm in diameter. The main elements in the granules include iron, nickel, chromium, carbon, and sulfur, with the content of nickel and that of iron of 9.08 wt.% and 85.21 wt.%, respectively.