Patent No. EP4175920 (titled "Method For Calcining Mineral Rock In A Regenerative Parallel-Flow Vertical Shaft Furnace, And Furnace Used") was filed by Lhoist Recherche ET Developpement on Jun 28, 2021. The application was issued on Apr 24, 2024.
A process for calcining carbonated mineral rock in a vertical straight furnace with regenerative parallel flows, characterized by fuel combustion in excess oxygen and introducing an oxidizing mixture formed by mixing the furnace effluent with concentrated oxygen back into the furnace to enhance CO2 concentration.

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