Mercury flows in a cement plant adopting circular economy policies

The principle of recycling materials has been adopted as part of the cement industry's contribution to the transition from linear to circular economy. This study examines mercury flow in a cement plant and investigates the impact of circular economy policies on mercury emissions. The raw material analysis indicate that steel industry sludge is the main mercury source (40.9 %), followed by limestone (23.0 %) and silica sand (13.4 %). Recycled materials, with a mercury content of 0.267 mg/kg, contribute more mercury than raw materials (0.065 mg/kg). The intermediates in the production process enrich mercury, with raw mill fly ash containing 19.7 mg/kg. Mercury output is primarily via flue gas (98.8 %), with a mass flow rate of 16.34 g/hr, while clinker accounts for only 1.1 %. The emission factor from the raw mill stack is 165 mg Hg/ton clinker, higher than those reported in previous studies. The mass balance is 130 %, within the acceptable range (70-130 %). While adopting circular economy policy is beneficial for waste management, it increases overall mercury emission from cement plants, necessitating improved recycled material quality and air pollution control measures.