Research Of Carbon Emission From Cement Production

Cement is a common building material,and its output ranks first among the industrial products used,with an annual global output of about 4 billion tons.Carbon dioxide（CO₂）is emitted during the cement production process.According to statistics,the cement industry’s CO₂emissions account for about 7%of the total emissions,and the cement industry is under great pressure to save energy and reduce emissions.Therefore,it is urgent to analyze the carbon emissions of cement production to provide a theoretical basis for the carbon emission reduction work of cement enterprises and the research of new low-carbon cement.Based on the high-temperature reaction process of cement clinker calcination,thermodynamics and cement production processes,this paper establishes a theoretical calculation model of CO₂emissions from cement production and develops corresponding calculation software,analyzes the composition of carbon emission sources of cement production,and compare and verify according to the actual production data of the cement plant.The details are as follows:（1）Establishment of theoretical calculation modelThe cement production processes are mainly divided into raw material preparation,clinker calcination and cement production.CO₂emissions are mainly composed of carbonate decomposition,fuel combustion and electricity consumption.Based on the high temperature reaction process of cement clinker calcination,thermodynamics and cement production processes,a theoretical calculation model for CO₂emissions from cement production is established.The theoretical CO₂emissions in the cement production process can be calculated by this analysis model,based on the clinker mineral composition and cement composition,without the actual production data of the factory.（2）Theoretical CO₂emissions from clinker mineral productionBy assuming that clinker consists of only a single mineral,the theoretical model can calculate the theoretical CO₂emissions from clinker minerals（C₃S,C₂S,C₃A,C₄AF,and C₄A₃S）.The calculation shows that the main mineral C₃S of ordinary Portland cement（OPC）clinker has the highest CO₂emissions of 949 kg/t;while the major mineral of Calcium sulfoaluminate cement（CSA）,C₄A₃S produces the lowest CO₂emissions,at 464kg/t.CO₂emissions from carbonate decomposition account for the largest proportion of these minerals.（3）CO₂emissions from clinker productionThe calculation compares OPC clinker,high-belite Portland cement（HBC）clinker,CSA cement clinker and rapid-setting and hardening,high-belite Calcium sulfoaluminate（rapid-setting and hardening HB-CSA）cement clinker.The CO₂emissions of the four clinkers of OPC,HBC,CSA and rapid-setting and hardening HB-CSA are 864 kg/t,796kg/t,572 kg/t,and 539 kg/t.CO₂emissions from carbonate decomposition still account for the largest proportion of the four types of cement clinker,ranging from 59%to 65%;followed by fuel combustion,which accounts for about 33%;CO₂emissions from electricity consumption account for the lowest,about 5%.（4）CO₂emissions from cement productionThe CO₂emissions of OPC cement P·O42.5,HBC cement P·LH42.5,CSA cement R·SAC42.5,and rapid-setting and hardening HB-CSA cement BS-HFR42.5 are calculated,respectively 709.9 kg/t,759.1 kg/t,418.9 kg/t and 310.2 kg/t.