Upgrading of low-grade metallurgical coke by CH_4 cracking

1. 为提高焦炭的抗氧化性，对焦炭进行了甲烷裂解渗透处理。观察了焦炭在渗透氧化过程中气孔结构的变化。实验证明，浸渍焦炭氧化后的机械强度高于未浸渍焦炭。结果表明：1)渗滤使焦炭反应指数（CRI）由32左右下降到18左右。2)测定了渗焦炭反应后的机械强度（CSR）。CSR指数从56左右上升到77左右，与特高品位焦炭的值相对应。3) CSR的增强是由于中孔中沉积了碳，阻止了氧化过程中微孔面积的增加。为了阐明微孔的渗透机理，以活性炭为样品进行了研究。采用氮气吸附-解吸法对微孔及亚微孔进行了表征。中孔和大孔也用汞孔隙度来表征。结论总结如下：1)渗透后活性炭的微孔体积和表面积分别减少到原样品的0.1和0.2%左右。微孔中，亚微孔被完全填充。中孔和大孔的体积和比表面积分别减少约3%和32%。2)在氧化过程中，沉积在大孔中的碳几乎燃烧殆尽，而沉积在中孔和微孔中的碳仅部分燃烧殆尽；渗透样品的表面积增加比例最小的是微孔。从这些实验结果可以推断，沉积在微孔中的碳对阻挡CO2侵入起主要作用，从而增强了抗氧化性。

1. In order to modify the coke so as to increase the oxidation resistance, coke was infiltration by methane cracking. The pore structure change of metallurgical coke accompanying infiltration and oxidation was observed. It was proved experimentally that the mechanical strength after oxidation for the infiltrated coke was higher than for untreated coke. The result is summarized as follows :1) Coke reactvity index (CRI) decreased from about 32 to 18 by infiltration.2) The mechanical strength of coke after reaction (CSR) was measured for the infiltrated coke. The index of CSR increased from about 56 to 77 which corresponds to the value of the extremely high grade coke.3) The enhancement of CSR is caused by the deposited carbon in meso-pores, preventing from increase in the area of micropores during oxidation.2. To ellucidate the mechanism of infiltration of micropores, an activated charcoa was used as a sample. The meso-and the micropores including submicropores were characterized by use of N2 adsorption-desorption method. The meso-and macropores were also characterized by mercury porosimety. The conclusions are summarized as follows.1) The volume and the surface area of micropores of the infiltrated activated charcoal are reduced to about 0.1 and 0.2% of those of the original sample, respectively. Among the micropores, the submicropore is filled completely. Concerning the mesopore and the macropore, the decrease ratio is about 3% and 32% for volume and surface area, respectively.2) When oxidized, the carbon which deposited in macropores is almost burned but that in meso-and micropores is only partly burned ; The ratio of increase in surface area of the infiltrated sample is smallest for the micropores. From these experimental results, it is deducible that the deposited carbon in micropores plays the major role for blocking CO2 intruding, thereby the resistance against oxidation is enhanced.