The global steelmaking industry faces urgent pressure to reduce greenhouse gas emissions and transition toward sustainable, low-carbon production methods. Traditional ironmaking relies heavily on injecting pulverized fossil coal into the lower raceway of blast furnaces to generate necessary heat and reducing gases. Concurrently, agricultural residues such as green coconut shells present severe municipal waste management problems, particularly in tropical regions where up to 90 percent of coconut biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More is discarded, openly burned, or dumped into waste ponds. Converting abundant coconut waste into biochar through low-temperature thermal processing presents a circular economy opportunity to partially replace fossil coal in pulverized coal injection systems without requiring major structural modifications to existing steelmaking facilities.

The primary technical challenge in implementing raw biomass directly into blast furnaces stems from its high volatile content, low fixed carbon density, and high moisture levels. Furthermore, biochar ashAsh is the non-combustible inorganic residue that remains after organic matter, like wood or biomass, is completely burned. It consists mainly of minerals and is different from biochar, which is produced through incomplete combustion.   Ash Ash is the residue that remains after the complete More typically contains high concentrations of basic alkali oxides, such as potassium oxide and sodium oxide, which elevate the alkalinity index and raise concerns regarding slagging, fouling, and refractory lining wear inside high-temperature reactors. The research team addressed these limitations by systematically converting green coconut shells into biochar across four distinct pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More temperatures ranging from 200°C to 450°C. The resulting materials were evaluated for yield, chemical composition, heating value, ash fusibility temperatures, and dynamic combustion behavior to establish their physical and chemical compatibility with standard industrial injection coals.

Thermogravimetric testing showed that biochar produced at a mild pyrolysis temperature of 200°C achieved the best operational compromise, yielding a solid mass recovery of 40.5 percent alongside an attractive ash content of 8.0 percent. While pure biochar exhibited a high alkalinity index of 32.40—substantially above the 2.06 to 3.08 range seen in reference pulverized coals—combining the materials mitigated inorganic slagging risks while leveraging the catalytic properties of basic oxides to accelerate overall reaction rates. Isothermal combustion analysis at 1000°C revealed that adding biochar significantly increased maximum mass loss rates and shortened overall reaction times compared to pure coal, delivering faster ignition and rapid volatile release.

When mixing the 200°C coconut biochar with reference mineral coal at varying concentrations, the engineering team identified an optimal formulation consisting of 30 percent biochar and 70 percent coal. This 30/70 composite successfully satisfied critical industrial quality metrics, including fuel ratio, combustibility index, and volatile ignitability thresholds, while mirroring the overall thermal decomposition profile of standard injection fuels. By incorporating a 30 percent renewable, carbon-neutral biocarbon fraction directly into blast furnace operations, steelmakers can achieve immediate reductions in net carbon dioxide emissions, providing a viable pathway toward sustainable metal manufacturing.

Source: Padilla, E. R. D., Mortari, D. A., Luna, C. M. R., de Campos, C. I., Barriocanal, C., Resende, R. S., & Yamaji, F. M. (2026). Blending PCI coal and biochar as sustainable alternative for blast furnace fuels. BioEnergy Research, 19(1), Article 116.