CO_2 emissions derived from raw materials used in brick factories. Applications to Andalusia (Southern Spain)

摘要

The aim of this study is to evaluate C02 emissions from raw materials, fired in the structural ceramic industry in Andalusia. Twenty representative ceramic industries from the greatest ceramic production sites in Andalusia were selected. These industries produce more than 75 t of building ceramic materials per day and are affected by the commercial emissions system. Raw materials, fired products, and their corresponding unfired products ("green bodies") were studied by XRD. The overall amount of carbon content was determined by elemental microanalysis. CO2 from carbonates and organic matter was evaluated by calcimetry and the Walkley and Black (1934) method. In most of the brick industries, CO2 emissions are produced by carbonates decomposition because the raw materials they use generally contain high amounts of these minerals (up to 50%). Sometimes, raw materials such as sericitic shales and white-firing grey-black clays ("kaolinitic" clays) are used in the production of pavements and facings. In these cases, CO2 emissions usually come from the destruction of the organic matter (up to 4%). The CO2 content obtained by elemental analysis and calcimetry, had a reasonably high correlation (r = 0.98), except for the shale samples and other raw materials with organic matter. On the basis of CO2 emissions, other than those coming from fuel combustion, there are three types of ceramic factories in Andalusia: a) factories that release <5% of CO2 emission. They manufacture special products and do not use raw materials containing carbonates, b) factories that release between 5-10% of CO2 emission. The content of carbonate in the raw material they use ranges between 20-30%. In this case, the amount of CO2 produced should be controlled in order to evaluate how dangerous the emissions are, c) factories releasing above 10% of CO2 emission. They are factories that use marls from Neogene sediments of the Guadalquivir Basin, containing carbonate >30%, and even up to 50%. The amount of CO2 produced should be evaluated in order to avoid emissions, which could constitute a serious environmental problem. Studies like these ones applied to Andalusia may be implemented in other Spanish regions and European countries to evaluate the CO2 emissions by ceramic industries. This type of CO2 emission is not negligible in relation to the overall CO2 emission of the industries of any country.