8th International Congress on Science and Technology of Ironmaking - ICSTI 2018

Tribological and scratch testing techniques were applied to metallurgical coke samples to determine (1) the abrasive strengths of the coke microtextural constituents, and (2) the strength of the interfaces between the inertinite maceral derived components (IMDC) and the reactive maceral derived components (RMDC), as a function of the properties of the parent coal(s). These parameters were quantified via the application of advanced microscopy techniques and then related to fundamental coal properties, including rank, measure, petrographic composition, and grind characteristics. During tribological testing, a stationary pin or ball indenter is under a controlled load in contact with a rotating polished block of the material being tested. The wear track is then analysed to determine the degree and nature of the damage to the surface. The wear that occurs in rotational tribology tests is due to the progressive loss of surface material at the points at which the two surfaces (the polished block and the indenter) come into contact as they rub against each other. One of the key measurements that can be obtained from tribological testing is the coefficient of friction (COF). The frictional force between the polished coke block and the indenter shows their resistance to relative motion, and indicates the susceptibility of the coke to tribological wear. The higher the COF, the greater the efficiency in transferring mechanical energy to the coke that can weaken or break it up. The strength attributes of cokes were related to coal properties, demonstrating that tribological and scratch testing techniques can be used to distinguish between cokes of different coal origin. The key findings were: (1) IMDC abrasion is insensitive to parent coal rank. (2) RMDC abrasion is sensitive to parent coal rank. (3) RMDC fracture mechanisms are insensitive to parent coal petrographic composition. (4) Coal blending was found in most circumstances to produce stronger RMDC-IMDC interfaces than were obtained in the cokes formed from the constituent single coals. The essential next step will be to use these findings to identify a path to help improve coke strength prediction and coke resistance to abrasion in the blast furnace. This would help to improve the accuracy of models used by the coal technical marketing industry to predict the value of their coal and coke products.