The use of natural biomass as a substitute for fossil fuels in the production of iron ore pellets is a promising approach for significantly reducing greenhouse gas emissions. Prepared biomass is already used as a source of in-bed heat in the production of hematite pellets instead of solid fuel (coal) with virtually no reduction in the quality characteristics of the pellets, and in some cases even improving them (reducibility, swelling index).

   The use of alternative heat sources to reduce gas consumption in the production of magnetite pellets has found its application in the last decade. Several heat sources were considered - wood sawdust, sunflower seed husks, nutshells, rice husks. Since the production of magnetite pellets practically does not use an intra-layer heat source (solid fuel), the use of biofuel was aimed at partially replacing the gaseous fuel supplied to gas burners installed in the heating and firing zones and providing the necessary thermal conditions for the pellet production process. Testing of various types of biofuel showed the greatest efficiency of the thermal process when working on a combined type of fuel - natural gas/biofuel when using sunflower seed husks as biofuel (the chemical composition is given in table). The technological process of biofuel preparation before feeding into the furnace of the firing machine involves crushing sunflower seed husks to a fraction of 2-4mm, grinding with drying to a fraction of 0-1mm and feeding by pneumatic transport into the combustion chambers of the furnace of the thermal unit. Each such chamber, into which the prepared biofuel is fed, is equipped with a special, high-temperature burner installed next to the stationary burner. Biofuel is fed into the torch of the main burner. Usually, from 6 to 10 biofuel devices are installed on conveyor firing machines. For more complete combustion of sunflower seed husks, it is desirable to distribute the required volume of biofuel feed to the maximum number of burners and the prepared fuel should have the smallest possible granulometry composition and moisture content. The replacement of natural gas with sunflower seed husks is about 46-50%.

     The main disadvantage of this technology is the wear of the pneumatic conveyor feed pipelines, especially at the bends, the wear of the biofuel burner devices themselves and slightly increased wear of the refractory lining of the combustion chambers due to local overheating and melting of the refractory material and the deposition of ash mass on the longitudinal walls and the roof of the furnace. Each biofuel device requires individual installation and regulation of the material feed torch into the combustion torch of the main burner. Also, after installing the biofuel devices, it is necessary to monitor the change in the amount of NOx, COx, SOx emissions through emission sources. The use of biofuel as a source of partial replacement of natural gas made it possible to reduce natural gas consumption by up to 50% at different percentages of replacement and did not affect the change in the quality characteristics of the pellets produced and the productivity of the thermal unit.