If the clinkerization reaction (the process of forming clinker, the main component of cement, from raw materials such as limestone and clay) occurs in a reducing environment, the quality of the cement may be affected. In a reducing environment, the iron in the raw materials may be reduced to metallic iron, which can cause the cement to be less durable and less resistant to sulfates. Additionally, the formation of metallic iron can lead to a decrease in the overall strength of the cement. Therefore, it is important to maintain an appropriate level of oxygen during the clinkerization reaction to ensure optimal cement quality.