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Owner of data set Polish Cement Association |
Technical purpose Cement is a material universally used in construction. The environmental properties of cement are increasingly frequently declared by producers to raise consumers’ environmental awareness and to foster low-carbon design of buildings. This Type III Environmental Product Declaration of CEM-I, CEM-II, CEM-III and CEM-IV, CEM-V produced at Polish plants was prepared based on the life-cycle assessment methodology in accordance with the guidelines of PN-EN 15804 Sustainability of construction works – Environmental product declarations – Core rules for the product category of construction products and ISO 14067:2018 Greenhouse gases — Carbon footprint of products — Requirements and guidelines for quantification. The carbon footprint is understood as the total emission of greenhouse gases caused directly during cement production including the following stages: mining of raw materials, their processing and the related energy consumption, the transport and the cement production process itself. The environmental impact has been expressed for the declared unit, i.e. for the reference unit of 1 kg of cement. The main stages of cement production are as follows: mining and purchase of raw materials, production of the raw meal, clinker firing, cement grinding, cement storage. Processes involved in producing cement by the wet and dry methods are presented in Figure 1.
The natural raw materials for cement production are mainly calcareous materials such as limestone or marl, sand and alumina-containing materials such as clay or shale, which are widespread. Alternative raw materials, such as ash and slag, are used in the process as substitutes for natural ones. The use of clinker substitutes contributes significantly to reducing the carbon footprint of cement. The weight proportions of raw materials for producing CEM I – CEM V cements based on SPC declarations and statistics are presented in Table 1. The share of CEM I by weight in the domestic cement production amounts to approx. 46%, of CEM II – 41% , CEM III – 12,4%, and of CEM IV and CEM V to less than 1%.
In 2017, the annual production of clinker used to produce cement amounted to: 12,838,930 tons by the dry method and 95,400 tons by the wet method, while the total cement production was equal to 17,119,300 tons. Raw meal is produced in both the wet and dry method process (Fig. 1). In the wet method, the raw meal is turned into a slurry before burning. The slurry is homogenised and pumped into the kiln. In the dry method, the mix is usually produced in a single-step grinding process. The heat of process gases is used for drying. The quantity of cement produced by the wet method is decreasing with every passing year. Raw meal is preheated using input gases and then fired in a rotary kiln at a temperature of approximately 1450ºC. The main fuel used in the process is hard coal (35.2%, Table 2). Alternative fuel that is used is derived from waste and its share is growing with every passing year. A large proportion of alternative fuel contains biomass with a low carbon footprint coefficient (Polish average 0.049 MgCO2/GJ). The use of alternative fuel significantly reduces the carbon footprint of cement. The degree to which alternative fuels are used varies significantly within the territory of Poland. As measured by the amount of heat obtained from fuel during cement production, alternative fuel accounts for 64.4% of ]total energy. Types and quantities of fuel are presented in Table 2. The calorific value of fuel was selected based on literature and statistical data (KOBIZE).
In 2017, the amount of CO2 calculated according to CITL was 10,269,800 tons. Calculated per clinker production, this represents 0.794 Mg CO2/ton of clinker. The process emission factor amounted to 0.51 Mg CO2/ton of clinker. Clinker is ground together with additives. The statistical average consumption of energy for cement grinding is equal to 48.1 kWh/ton. The total electricity consumption in cement production amounts to 104.5 kWh/ton. The emission ratio of electricity generation in Poland is 0.73 kg/kWh (Tauron) or 0.778 kg/kWh (KOBIZE). The LCA assessment took into account the production phase (A1-A3, see Table 3) and the following processes/modules: A1 – raw material production: fuel mining, raw material mining, electricity generation, alternative fuel production; A2 – transport: raw material transport; A3 – production of the product: raw meal production, consumption of fuel for firing, electricity consumption for grinding. Table 3 shows the contribution of individual ingredients to the carbon footprint of cement established according to the available knowledge and the literature of the subject. |
