Papers by Keyword: Raw Meal

Abstract: Cement production belongs to the most important branch of industry. It is marked out by processing of great quantity of natural raw materials and of considerable energetic demand. Not only the intensification of the contemporary production processes is the permanent effort of the cement industry, but also the search for new energy less demanding methods. The paper is focused on one of the most important components of the intensification of cement production – on the preparation of raw meal. It mainly deals with the influence of granulometry and microhomogeneity of the input raw materials on the quality and economy of the process of production and on the final product. The study was carried out mainly by methods of optical microscopy and the determination of technological parameters of cements. It has been found that a change in granulometry of raw meal has a significant impact on the formation rate of the clinker phases. Subsequently, the grindability of the clinker and the strength of the cement are influenced, especially in the short-term hydration. Change of granulometry and homogeneity of raw meal can greatly optimize the quality and economy of the cement production process.

Abstract: Portland clinker is thanks to its large-scale production a continuously studied topic. Clinker, or Portland cement, is used for construction purposes or for insulation and special applications. One of these special applications could be shielding of different types of radiation by making use of the content of barium ions. The present article examines the influence of barium oxide on the formation and properties of Portland clinker, which could be, by incorporation of barium ions into the system, used as a binder for buildings resistant to various types of radiation. Barium sulphate and barium carbonate were added to the raw meal in order to prepare clinkers with different content of barium oxide. The effect of barium on the formation of clinker phases was studied (by XRD – Rietveld analysis and by the microscopic point counting method), as well as the rate of alite formation under isothermal conditions. Furthermore, the ability of barium to become a part of clinker minerals was studied by SEM with EDS.

Abstract: Sample polluted soil surrounding Shougang as object, TG, thermal analysis of raw soil and cement raw meal experiments were made, the results show that: the polluted soil contains a variety of PAHs of organic pollutants, the total concentration of PAHs is about 156.39ppm. PAHs contaminated soil can be divided into three stages of weight loss at 850°C: water losing stages, organic matter decomposition stages and inorganic carbonate decomposition stages. With the increase in heating temperature, removal rate of total PAHs in raw soil is high. Using polluted soil as cement siliceous raw material, except naphthalene, acenaphthene, two hydrogen acenaphthene and anthracene, other organic compounds of PAHs have residues at 300°Cand small amounts of phenanthrene have residue at 600°C, means cement raw material has certain adsorption of PAHs pollutants. Therefore, when co processing PAHs polluted soil into the cement kiln, considering should be focused the content of pollutants in flue gas volatilization and C2 raw mill especially.

Abstract: The sulfation behavior of calcined raw meal was investigated in a laboratory fix-bed reactor under conditions typically for SO2 capture in the kiln inlet housing used in cement production. The initial period is characterized with a fast-increasing conversion, while the second period shows a slow-increasing conversion. A desirable temperature exists for sulfation of calcined raw meal. A smaller particle size favors the sulfation reaction. The initial conversion rate is significantly promoted by a higher SO2 concentration. The SEM examinations show that the sulfation process involves nucleation and growth of CaSO4 grains- the sulfation product. Increasing the temperature and extending the time result in fewer but larger CaSO4 grains in the product layer.