<p>Organosilicon slag is a by-product from the production of organosilicon monomers, which is a type of chemical waste from the silicone industry. The heavy metals and chlorinated organic compounds contained in organosilicon slag can cause environmental pollution, but its richness in silicon monomer makes it valuable for resource utilization. In this study, the development of a new type of exothermic insulating riser sleeve using organosilicon slag as the basic exothermic agent was proposed. The effects of exothermic agents (organosilicon slag and aluminum powder), oxidizers (Fe₃O₄, MnO₂ and KNO₃), and a fluxing agent (Na₃AlF₆) on combustion performance, as well as the influence of organosilicon slag and hollow drift beads particle size distribution, and phenolic resin content on the air permeability and compressive strength of the riser, were also investigated. The results showed that a formulation comprising 21% organosilicon slag (75–150µm), 14% aluminum powder, 12% Fe₃O₄, 6% MnO₂, 4% KNO₃, 4% Na₃AlF₆, 12% phenolic resin, 36–38% hollow drift beads (75µm) and 1–3% alcohol reached a maximum temperature of 1542&#xa0;°C, a holding time of 210s, a secondary combustion time of 45s and an ignition time of 31s, meeting the performance criteria for exothermic insulating risers. Castings produced using the organosilicon slag riser exhibited defect-free interiors and a surface hardness of up to 200 HB confirming its suitability as a replacement for conventional aluminum powder exothermic insulating risers in casting production.</p>