Relevance between various phenomena during coking coal carbonization. Part 3: Understanding the properties of the plastic layer during coal carbonization

To understand the plastic layer properties, which directly impact coke quality during the coking process, the plastic layer characteristics formed by seventeen kinds of coking coals were analyzed using a penetrometer equipped on a thermogravimetry?plastometer?swelling pressure apparatus. The penetrometer-resistance (PR) curves of the plastic layer were obtained. Characteristic parameters of the plastic layer were determined from the PR curves. The relationships between these parameters and coal thermoplastic parameters were constructed and evaluated. Additionally, the interaction between the structural zones of the plastic layer was investigated. It was found that the plastic layer is composed of four structural zones, namely the increasing, decreasing, constant, and re-rising PR zones, in which the PR decreasing zone and constant zone are the critical zones for thermoplastic development. In contrast, the PR increasing zone does not have obvious thermoplasticity, and the PR re-rising zone goes against the thermoplastic development. Some derived parameters (PRmaxand PRmin, YDZ + YCZ, ( )/ YDZ + YCZ YRe?rZ) may be used as indicators to reflect the impermeability, internal thermoplastic properties, and caking performance of the plastic layer. These findings can provide an insight into the properties of the plastic layer during coal carbonization and maybe lay a foundation for coke quality prediction.