| Various of new technology has been put into practice with the upsizing of the blast furnace so that the quality of metallurgical coke should be improved in order to match with it. Meisteel has to purchased 600 thousand ton cokes every year because of the shortage of its own coke production capacity;But the purchased coke always lead to fluctuation due to the difference of production quality requirements and stangard. Therefore this paper selects three relatively stable purchased cokes,including Fulong(FL) Haiyan(HY) and Huaibei(HB) coke, to compare with the coke self-producted by 6m coke oven and 7m coke oven(referred to as MEG-6、MEG-7,respectively) in order to provide theoretical basis for purchasing stable qualified coke;Meanwhile the law of quality variability of the tuyere coke and mix coke(which was smelted by blast furnace) has also been analyed.The research of pore characteristics of different coke shows that the total pore volume of the coke is ahout 0.2 cm3/g when studied by mercury intrusion method,and purchased cokes are bigger about 0.06 cm3/g than self-producted cokes.The total surface area of different cokes are between 2 and 7 m2/g, in which the contribution of micropore of self-producted cokes reach up to 80%,what’s more,the purchased cokes even reach up to 90%.The pore volume of micropore of the cokes is about 2×10-3 cm3/g and the surface area is about 1 m2/g when studied by nitrogen adsorption method.The pore volume of micropore only accounted for about 1% of the total pore volume,but the micropore has contributed more than 85% of the surface area.The micropore is divided into supermicropore(d≤10nm) and submicropore(10<d<100nm),the pore volume of supermicropore is between 1×10-4 and 7×10-4cm3/g, while the pore volume of submicropore is about 2×10-3cm3/g,and submicropore accounted for more than 70% in the pore volume of micropore,and submicropore pore volume ratio has a linear relationship with reactivity.The optical tissue index(OTI) of purchased cokes are less than 150% while the self-product cokes are greater than 160%,and the degree of anisotropy are greater than that of isotropic in self-product cokes.The proportion of the mosaic structure in coke are 70% ~ 80% accounted for large part of anisotropic structure.The XRD patterns of purchased cokes are roughly the same while the self-producted cokes are almost coincident,and three purchased cokes whose aromatic layer orientation degree and aromatic layer size as well as the degree of condensation of aromatic nuclei areFL>HB>HY.The study of the tuyere coke(FKJ) and the into blast furnace coke(RLJ)demonstrates that the size of FKJ is greatly reduced and the average value is reduced to 37.35mm;Ash is increased and the average increase by 26%,and the content of Fe2O3 in the ash of coke with different particle sizes increased most and the Fe2O3 content in the minimum particle size of the coke is up to 55.45%,in addition the acidic oxide content decreased and the alkaline earth metal content increased;After the reaction of carbon solution in the blast furnace the total pore volume increased by0.0614 cm3/g and the total surface area decreased by 1.3357 m2/g, and the pore volume of the micropore below 1.5nm accounted for only about 0.4% of the total pore volume,but it provides about 50% of the surface area;The modulus of the coke decreased by 2.753 Gpa and the hardness decreased by 0.252 Gpa,and the mechanical properties of coke decreased only a little; The OTI of FKJ decreased by 19%,compared with RLJ,its degree of anisotropy reduced;Half-width of FKJ(002) peak and(100) peak were 1.54 rad and 1.76 rad,respectively,and half-width of RLJ(002)peak and(100) peak were 3.58 rad and 2.52 rad,respectively,and two peaks are all become higher and more narrow,the degree of graphite of FKJ was increased by0.09%;SEM observation shows that the FKJ particles become smaller,the particles become more round,but the surface porosity increases significantly. |
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