The Use of Thermography to Determine the Compaction of a Saddle-Shaped Briquette Produced in an Innovative Roller Press Compaction Unit

The unit compacting pressure in the fine-grained material consolidation process in the roller press can reach >100 MPa and is a parameter that results, among other things, from the properties of the consolidated material and the compaction unit geometry. Achieving the right pressure during briquetting is one of the factors that guarantee the proper consolidation and quality of briquettes. The distribution of the temperature on the surface of the briquettes correlates with locally exerted pressure. The present work aimed to analyse the briquetting process of four fine-grained materials in a roller press equipped with saddle-shaped briquette-forming rollers based on images obtained from the thermography conducted immediately after their consolidation. The tests were carried out in a roller press that was equipped with forming rollers of 450-mm diameter and having a cavity with a volume of 4 cm³, as described by patent PL 222229 B1. Two mixtures of hydrated lime with 9.1 wt% and 13.0 wt% water, a mixture of scale and a mixture of electric arc furnace (EAF) dust were used for the tests. In most mixtures, the highest temperatures were achieved in the middle-upper part of the briquettes. The briquettes from the EAF dust mixture heated locally the most on the surface up to 37.7 °C. The difference between the maximum briquette temperature and the ambient temperature was 20.2 °C.