Waste coffee shell are used as tempering agents and low-rank coal in industrial silicon smelting

[Display omitted] •The co-gasification characteristics of coffee shell and low rank coal are studied by RMS for the first time.•An effective influence mechanism was evaluated by combining dynamics.•Coffee shell can be used as a tempering agent in industrial silicon smelting.•Coffee shells are an attractive feedstock for the production of biomass carbon. Coffee shell (CS), a type of waste stripped off during the coffee production process, possesses practical significance and economic value. First, CS was examined to explore its synergistic strengthening effect when combined with unbonded coal (NC). The evaluation encompassed aspects of thermodynamiCS, gasification reactivity, and kinetiCS. As the CS proportion in the mixed carbon material increased from 10 % to 50 %, the gasification reactivity (R) increased from 1.203 to 2.427.Activation energy in the cracking phase Ea decreased from 146 to 87 kJ/mol (a decrease of 40 %), and the order of magnitude of A0 gradually decreased. This is attributed to the adsorption of alkali metal in CS onto NC, which reduced the activation energy required for fixed carbon cracking and involved kinetic compensation. The H released by the sharp reduction of hydrogen bond and methylene content in CS is mainly absorbed by NC in the form of methane, which promoted pyrolysis and gasification. Finally, a semi-industrial test in which CS was applied to industrial silicon smelting was conducted. The results show that the application of CS increases silicon production by 3.2 %, reduces carbon consumption by 6 %, and reduces energy consumption by 2.5 %. In silicon production, CS can effectively replace some carbon-containing materials as reducing agents, which can reduce carbon emissions and save energy. This approach also supports the industrial silicon industry’s shift from energy consumption control to carbon emission control, thereby yielding substantial economic value and social benefits.