Study On The Difference Of The Microstructure Of The Coke Under Different Coking Processes

With the development of larger blast furnace and pulverized coal injection, the requirements of the metallurgical coke were becoming higher. Due to the shortage of high qualified coal resources, tamping coking technology was rapidly developed. But the majority of tamping coke production were only used for small blast furnace, it also had the impact on blast furnace permeability and liquid permeability compared to top-loading coke. So this paper focused on tamping coke by micro-structure analysis,then revealed the differences between top-loading coke and tamping coke.This paper mainly studied the micro structure of three kinds of tamping coke and three kinds of top-loading coke. The macro-pore, meso-pore, micro-pore structures were characterized by mercury intrusion method and nitrogen adsorption method, the morphology and distribution of the porous structure were characterized by SEM method, the micro-crystalline structure of the coke was characterized by XRD, and coke optical texture was tested by HD microscope, the results showed:Despite the differences of coke quality indicators, the porosity of tamping coke was significantly less than top-loading coke, the porosity of tamping coke DF was30.21%, while the porosity of the top-loading coke MEG(6) was up to 35.16%. In the microscopic pore structure, the difference of macro-pore between tamping coke and top-loading coke was small, the specific surface area and pore volume, respectively,were about 0.1cm3/g and 0.01m2/g; the differences of meso-pore and micro-pore were larger, tamping coke MF in diameter of 0.1- 3μm, its micro-pore volume and specific surface area were 0.0208cm3/g and 0.1110m2/g, while the top-loading coke TL were0.0376cm3/g and 0.1974m2/g. Micro-pore volume in the total pore volume of tamping coke SN was up to 2.78, while the ratio of top-loading coke MEG(7) was 1.28.According to the characteristics, this paper reclassified the meso-micro pores, namely micro-pores(d <0.1μm), the meso-micro pores(0.1<=d <3μm) and meso-macro pore(3<=d <10 μm), and defined the shapes of micro-pores including cylindrical,conical, cracks and hemispheres.(002) peak and(100) peak intensity of microcrystalline structure of tamping coke and top-loading coke were even about 1100, while half-width of tamping coke SN(002) peak and(100) peak, respectively were 3.57 rad and 4.59 rad, while top-loading coke MEG(7) were 2.49 rad and 3.12 rad, the width of these two peaks of tamping coke were less than top-loading coke, so its aroma ply size and orientation degree were worse than top-loading coke.Coke optical texture was directly related to coke quality, tamping coke was made from weak caking coal, the data showed tamping coke had lesser degree of anisotropy in optical texture, the isotropic texture of tamping coke SN was 54.4%, while top-loading coke TL was 2.5%, so their OTI were 66.3% and 192.1%.