Quantitative Evaluation of Effect of Hyper-coal on Ferro-coke Strength Index

Abstract

The relationship between the strength and the microstructure of ferro-coke with hyper-coal (HPC) addition is investigated. In particular, we focused on the adhesiveness of coal particles. The strength of ferrocoke was evaluated by a tensile strength test and coke microstructure with increasing the amount of HPC addition was observed. In the observation of the microstructure, absolute maximum length and roundness of pores were measured. The result indicated that the strength of ferro-coke increases with an increase in the amount of HPC, because voids between coal particles decrease and adhesiveness of coal particles improve. A pore roundness of less than 0.2 intends coke strength, and the index decreases with HPC addition. We found that a pore roundness of less than 0.05 is included in voids between coal particles. It is suggested that mutual adhesiveness of coal particles is one of the factors affecting coke strength, and this factor can be evaluated by pores of roundness less than 0.05.

Effect of HPC (Hyper-coal) on Strength of Ferro-coke during Caking Temperature

“…11) Moreover, Uchida et al indicated that blending HPC into coal particles enhanced adhesiveness of coal particles and strength of coke while strength of coke decreased because adhesiveness of coal particles decreased due to the existence of metallic iron around coal particles in microscopic structure of ferro-coke. 12) These studies evaluated coke samples after carbonization and focused on the relationships between only two components, coal and iron or HPC. To investigate ferro-coke utilized in industrial processes, the evaluation of three components, coal, iron ore, and HPC is required.…”

“…This would indicate that thermoplastic components of coal were decomposed due to catalysis of hematite, and the adhesiveness of coal particles decreased. In the previous study, Uchida et al 12) defined pores with roundness of less than 0.05 as non-adhesion pores with iron particles between coal particles in experiments with ferro-coke combined with HPC, and reported that adhesiveness of coal particles can be evaluated by finding the pores with roundness of less than 0.05. In the present study, the existence ratio of pores with roundness of less than 0.05 was used as index of the adhesiveness.…”

Effect of Iron Ore Reduction on Ferro-coke Strength with Hyper-coal Addition

“…HPC begins to soften at low temperature, shows a high fluidity, and demonstrates the possibility of enhancing coke strength by blending with low-rank coals. 10) Uchida et al 11) reported that iron oxide occupies the spaces between coal particles in ferro-coke and inhibits the adhesiveness of coal particles. However, these researchers also showed that blending HPC in ferro-coke enhances the adhesiveness of coal particles as well as coke strength and summarized that the adhesiveness of coal particles is one of the dominant factors in coke strength.…”

“…The tensile strength of the samples carbonized at 1 000°C is measured using the same diametral compression test used previously, 11) and the scale parameters are evaluated by Weibull plots. A total of 14 or 15 tests are conducted for each condition.…”

Evaluation of Properties of Hyper-coal with Iron Oxide Addition in Thermoplastic Range

“…Uchida et al 12) reported that although the strength of ferro-coke decreased because the iron particles inhibited coal particles adhesion, the strength of ferro-coke with added HPC increased because the coal particle adhesion was improved. Kannari et al 13) reported that the fluidity of coking coal with added Fe2O3 decreased, because the tolueneinsoluble and pyridine-soluble fractions of the coking coal were decomposed by the Fe2O3.…”