clinker production, UPR, ecoinvent 3.6, Undefined
Location: BR - Brazil
The dataset describes the production of Portland cement clinker in Brazil.
Clinker is the main constituent of Portland cement and also the main responsible for its environmental impacts. Clinker is made by sintering a mixture composed mainly of limestone and clay (called “raw meal”) at temperatures up to 1450 °C. Both primary and secondary fuels are used to this end. After sintering, clinker nodules have a diameter between 5 mm and 25 mm.
Clinker consists of various calcium silicates including alite (3CaO.SiO2 or “C3S”) and belite (2CaO.SiO2 or “C2S”). Tricalcium aluminate (3CaO.Al2O3 or “C3A”) and calcium aluminoferrite (4CaO.Al2O3.Fe2O3 or “C4AF”) are other common components, added to reduce the sintering temperature of the calcium silicates. For special cement types, such as low heat and sulfate resistant, it is necessary to limit the amount of tricalcium aluminate formed.
Naturally occurring calcareous deposits such as limestone, marl or chalk provide calcium carbonate (CaCO3) and quarries are often close to the cement plant. Clay, shale and sand are the preferred sources for silica. Iron ore and bauxite are the main sources of iron oxide and alumina. Raw materials are mixed at a certain proportion and are milled together in an operation called pre-homogenization, producing the “raw meal”. To ensure high cement quality, the chemistry of the raw materials and of the raw meal is very carefully monitored and controlled.
Portland cement clinker is made by heating the raw meal in a rotary kiln (calcination). As the kiln rotates, the material slides and tumbles down through progressively hotter zones towards the flame. The fuel is fired directly into the end of the kiln. The calcination reaction (CaCO3 → CaO + CO2) emits carbon dioxide into the air, and fuel combustion generates several air emissions. Different types of fuels can be used, including fossil fuels, biomass and wastes. The use of waste fuels in the cement kiln is called “coprocessing”.
Depending on the process configuration, the kiln can be preceded by preheating and/or precalcining steps. Preheating consists of a series of cyclones through which the raw meal is passed, coming in contact with swirling hot kiln exhaust gases moving in the opposite direction. The precalciner is a combustion chamber at the bottom of the preheater, at the entry of the kiln.
After the kiln, clinker is cooled and stored in silos. Clinker production plants are usually integrated with cement plants.
Primary data were gathered from six cement manufacturers in Brazil, who informed the total values of inputs and outputs related to clinker production in 2016, considering all their clinker production sites. All types of flows were reported, namely: primary and secondary raw materials and fuels, auxiliary materials, electricity consumption, water consumption and air emissions (from emissions monitoring reports). It corresponds to 70% market share, considered a good representativeness level.
Undefined unit processes (UPRs) are the unlinked, multi-product activity datasets that form the basis for all of the system models available in the ecoinvent database. This is the way the datasets are obtained and entered into the database by the data providers. These activity datasets are useful for investigating the environmental impacts of a specific activity (gate-to-gate), without regard to its upstream or downstream impacts.
Current technology for clinker production in Brazil, in dry kilns, considering various fuel types.
According to the GNR database, 49% of the clinker is produced in dry kilns with preheater and precalciner, being the other 51% produced in mixed kiln types (dry). Regarding fuel types, 80,5% are fossil fuels, 10,4% biomass and 9,1% alternative fossil and mixed wastes (data from 2014). According to SNIC (2013), there are 88 cement factories in Brazil. 57 are integrated plants that produce clinker and cement (ABCP, 2016), being 38 of them licensed for coprocessing.
Sources:
SNIC (National Union of the Cement Industry). Relatório Anual 2013 (Annual report 2013). 2013.
ABCP (Brazilian Portland Cement Association). Panorama do coprocessamento - Brasil 2016 (coprocessing panorama Brazil 2016). 2016.
ecoinvent EULA