Pulverised biocoal as a solution for heavy industries
Despite the rapid rise of renewable energy, the world still runs on fossil fuels. In addition to producing power, oil and coal in particular are also used to manufacture materials needed by society. The easiest sector in which to replace oil is transport with the introduction of electric vehicles and, more recently, even trucks and ferries. Replacing coal in base load power production or in vital areas of the manufacturing industry, like steel and cement, is much more complicated. However, solutions exist in the form of biocoal.
Global coal use, which reached an all-time high in 2024 at almost 8.8 billion tons, focuses on two varieties, power generation and coking coal for the metallurgical industry. The share for power generation was the largest with China alone burning around 4.1 billion tons for the purpose (85% of its coal use), whilst metallurgical coal globally was around 1 billion tons. Coal use varies based on end use, the type of coal and by the method of using it. Different fossil coals have different characteristics in, for example, volatiles content, grindability, ash and sulphur content, etc.
While the majority of the metallurgical coal is used in lump form in coking ovens for blast furnaces, the majority of coal for power production is used in pulverised form. There are some pulverised user cases in the metallurgical industry as well, mainly blast furnace tuyere injection (PCI) and slag foaming in electric arc furnaces. Since pulverised coal dominates global coal use, any viable alternative must be able to meet this requirement.
Proven method for pulverising biocoal
There are various methods for analysing coal grindability, one standardised method being the Hardgrove Grindability Index (HGI). However, traditional testing methods might not be suitable for biocoal due its hardness being more “artificial” than that of fossil coal.
Despite the HGI index of biocoal, we can safely say that there is one proven method for milling biocoal using a device built by Klingmill in Sweden. Instead of compressing the material between two metal surfaces, the biocoal is fed into a chamber containing a rotor equipped with thousands of small, sharp knives, which effectively cut the biocoal into fine dust.
Joensuu Biocoal, a biocoal production company, conducted testing in autumn 2025. In the tests, Joensuu Biocoal briquettes were pulverised using Klingmill’s device. During testing, Joensuu Biocoal’s biocoal briquettes were efficiently pulverised, with nearly 90% of the particles being below 0.25mm and, when fired in a test burner, worked better than biomass dust used as comparison material.
The grindability test on Joensuu Biocoal briquettes under controlled testing conditions confirmed that the material can be pulverised into the fine form required for use in pulverised applications. The next step is industrial use to verify performance and further optimise the process under real operational conditions.
Replacing fossil coal with biocoal in pulverised form can also bring improvements in operational reliability and safety. The compact design of the pulverising device minimises air volume, thereby effectively reducing the risk of explosions, which are relatively common in conventional coal mills.
Further testing and trials are expected to reveal additional techniques for effectively pulverising biocoal.
Biocoal as a drop-in solution
When transitioning the pulverised coal-based process to biocoal, the processes can be conducted almost unchanged and with the same equipment and method as fossil coal, but with 10% higher throughput to compensate for biocoal’s slightly lower specific energy content.
Beyond the straight forward drop-in approach, alternative approaches can offer added reliability and flexibility. The steel and cement industries typically rely only on one coal mill for the whole process. Building an additional grinding line next to the existing fossil coal one and having two 100% independent feeding lines improve operational reliability and allow instantaneous fuel flexing.
To summarise, biocoal can serve as a substitute for fossil coal in the majority of applications and performs well in processes requiring a pulverised form. While some of its properties differ from fossil coal, it retains the key characteristics of energy coal in a bio-based form and functions effectively as a renewable drop-in solution.