Study on Self-Heating of Biocarbon at Different Surrounding Temperatures

Metal production is a highly energy- and resource-intensive industry that relies heavily on carbon as both a reducing agent and an energy source. Biocarbon has been considered as a promising material to replace the conventional fossil carbon for metal production to reduce CO₂ footprints of metallurgical industry. However, in comparison to fossil carbon, the biocarbon has relatively high potential regarding self-heating and self-heating during storage, transportation and handling. The aim of this study is to investigate self-heating and self-ignition of biocarbon upon contact with synthetic air at low temperatures in the range of 140-250°C. The test self-heating and self-ignition of biocarbon powder was tested using a fixed bed reactor with controlling the surrounding temperature and adjusting flow of supplied air. Along one test, the emission of CO₂ and CO was monitored continuously. The self-heating and self-ignition of one biocarbon sample was tested under different temperatures at 180, 190, 200 and 250 °C with supplying of varied flow with 0.5 L/min, 1 L/min and 2 L/min. The results showed that temperature is a key factor that leading to self-heating of the studied material. For the test conducted at the temperatures below 200°C, no evident increase of temperature measured in the core of sample bed was detected. And no release of CO₂ and CO was monitored. For the test conducted at 200°C, the reactions started as the temperature is approaching this desired temperature, with slow release of CO₂ and CO and decrease of O₂. More intensive reactions took place and measured temperature increased dramatically during the first 15 minutes holding of the sample at 200°C, which was accompanied with intensive release of CO₂ and decrease of O₂. Afterwards, even with continuous supplying the synthetic air, only a slow increase of temperature measured from in core of sample bed was detected. During this stage, only the release of CO₂ and CO is rather stable, indicating smoldering combustion of the material. The findings for from this work indicate combination of temperature measurement and monitoring of gas emissions can be an important measure to identify self-heating and self-ignition of biocarbon. Alarm thresholds for biocarbon can be established based on such measurements, which helps to prevent and reduce risks related to self-heating and self-ignition of biocarbon along the value chain from production to final application. © 2026 Italian Association of Chemical Engineering - AIDIC. All rights reserved.