<p>The lime industry must urgently decarbonize, as conventional production is resource-intensive and generates substantial CO₂ emissions and thermal waste. This study addresses the challenge by implementing and validating a comprehensive 4Rs (Reduce, Reuse, Recycle, Recover) circular economy framework in a Parallel Flow Regenerative (PFR) twin-shaft lime kiln. A thermodynamic simulation was developed in Aspen Plus V9 using plant data from a 297 t/d kiln and validated against plant data with errors ranging from 1.8% to 8% (average 4.5%), with the largest deviation (8%) attributed to low-concentration MgO measurement uncertainty. The integrated 4Rs strategy yields significant quantitative gains: AI/ML(Artificial Intelligence/Machine Learning)-driven process optimization (Reduce) minimizes inputs; waste heat recovery (Recover) preheats combustion air to 650&#xa0;°C, achieving 15–20% fuel savings; a new carbon capture design (based on a circulating CO₂ carrier gas) recovers 65% of process CO₂ as a high-purity (&gt; 95%) by-product; and material loops for kiln dust and spent lime are closed via recycling and reuse, elevating material recovery above 90% (including exergy credits). The model shows that systemic 4Rs integration reduces specific energy consumption by ~ 19%, cuts total CO₂ emissions from 1.20 to ≤ 0.42 t CO₂/t lime (≈ 65% reduction), and transforms waste streams into valuable resources. This work provides a validated, scalable blueprint for converting conventional lime plants into net-zero, circular industrial hubs, aligning with EU Circular Economy Action Plan targets and deep decarbonization pathways.</p>