Cokes strength

Maceral behaviour and interaction on carbonization Mesophase development during carbonization Relation of coke strength (stability) to coke texture, pore size distribution, pore wall thickness... 

The only standard test method that is available is actually a test method for determining coke reactivity and coke strength after reaction (ASTM D-5341). This test method describes the equipment and techniques used for determining lump coke reactivity in carbon dioxide (CO2) gas at elevated temperatures and its strength after reaction in carbon dioxide gas by tumbling in a cylindrical chamber. 

ASTM D-5341. Standard Test Method for Measuring Coke Reactivity Index (CRI) and Coke Strength After Reaction (CSR). 

The discussions about the effect of petroleum coke on coke strength. 

Figure 2 illustrates the relationship between the coke strength (DI30/15) and the maximum fluidity (MF) of blended coals in the coke oven battery at Nippon Kokan s Fukuyama Works with the reflectance (Ro) of blended coals as the parameter. 

Coals produced in various parts of the world may be arranged in terms of Ro and MF as shown in Figure 4, which is referred to as the MOF diagram. Thus, Ro and MF have significant meanings in the evaluation of a coal in terms of coke strength. 

Figure 5. Effect of fluidity and coal rank of coal blend on coke strength.

Figure 7. Influence of rank (as measured by vitrinite reflectance) and type (as measured by percentage of reactive macerals) on metallurgical coke strength. Contour lines of equal coke strength (tumbler stability) were calculated by the author according to the procedures pioneered in the U.S. by Schapiro...

It therefore appears that pitch coke breeze additives can enhance the coke strength of poorer quality caking coals and that the pitch coke breezes of lower HTT (higher volatile content) produce the best results. It should be emphasized that only one variable (HTT of the breeze) has been investigated here other variables include size and shape of the breeze particles and percentage by weight added to the carbonization system. 

When coal is heated, it passes through a plastic stage, which is an indication of the initial softening, chemical reaction, gas liberation, and resolidiflcation process within the coke oven and is an important requirement in the coke blend required for end product coke strength. In addition, the fluidity of the plastic stage is a major factor in determining what proportion of coal is used in a blend. 

The usual method for measuring coke strength (resistance to abrasion and impact) is by measuring the size degradation that occurs in a tumbler drum. The different drum tests were devised to maximize the measurement in degradation between various cokes. 

The higher the remaining mass of coarse particles, the higher the coke strength and with it RI [53]. 

---