Biomasa jest jednym z najważniejszych źródeł pozyskiwania energii odnawialnej w energetyce. na całym świecie prowadzone są badania, mające na celu efektywne i ekonomicznie opłacalne zwiększenie wykorzystania biomasy do produkcji energii (Vassilev i in. 2010(Vassilev i in. , 2013c. spalanie biomasy, tak jak paliw konwencjonalnych, powoduje powstawanie stałych ubocznych produktów. szacuje się, że około 480 milionów ton popiołu ze spalania i współspalania biomasy może zostać wygenerowane na całym świecie co roku, przy założeniu, że ilość spalanej biomasy wnosi 7 miliardów ton/rok (Vassilev i in. 2010(Vassilev i in. , 2012(Vassilev i in. , 2013c. wpływ na wykorzystanie odpadów ze spalania i współspalania biomasy mają ich właściwości fizykochemiczne, które z kolei zależą przede wszystkim od rodzaju biomasy oraz technologii spalania. wszystkie te czynniki sprawiają, że odpady powstałe po spaleniu biomasy posiadają bardzo różnorodne i zmienne właściwości. znaczną część tych odpadów stanowią popioły lotne, których zmienne składy chemiczne i fazowe czynią je trudnymi do zagospodarowania (rajamma i in. 2009).zgodnie z hierarchią metod postępowania z odpadami, jeżeli nie da się zapobiec ich powstaniu, należy je poddać recyklingowi albo innemu rodzajowi odzysku. Popioły ze spalania biomasy (10 01 03) oraz współspalania biomasy (10 01 17) są wykorzystywane gospodarczo. Problem stanowią popioły fluidalne ze spalania biomasy zaliczane do odpadów 10 01 82, które nie są poddawane odzyskowi (emitor 2014; Uliasz-Bocheńczyk i in. 2015a).
The β-γ polymorphic transition of calcium orthosilicate (C2S) is a key phenomenon in cement chemistry. During this transition, the compound expands due to structural changes and a significant reduction in its density is observed, leading to its disintegration into a powder with a very high specific surface area. Owing to this tendency of the C2S material to “self-disintegrate”, its production is energy-efficient and thus environmentally friendly. A physicochemical study of the self-disintegration process was conducted with the aim of determining how the amount of dodecacalcium hepta-aluminate (C12A7) in calcium orthosilicate (C2S) affects the temperature at which the polymorphic transi-tions from α’L-C2S to β-C2S and from β-C2S to γ-C2S undergo stabilization. The applied techniques included differential thermal analysis (DTA), calorimetry and X-ray diffraction (XRD), and they made it possible to determine what C2S/C12A7 phase ratio in the samples and what cooling rate constitute the optimal conditions of the self-disintegration process. The optimal cooling rate for C2S materials with a C12A7 content of up to 60 wt% was determined to be 5 K·min−1. The optimal mass ratio of C2S/C12A7 was found to be 70/30, which ensures both efficient self-disintegration and desirable grain size distribution.
Studies were made of the dehydroxylation of several aluminium hydroxide modifications and the kinetics of a-A1203 formation. The investigated samples differed in both mineral composition and the level of alkali admixtures. It was found that the rate of formation and the quantity of a-A1203 depend mainly on the purity of the aluminium hydroxides, while the transition forms of alumina depend on the initial type of the aluminium hydroxide.Alumina is currently a valuable construction material in the various branches of industry. Its wide-ranging applications demand that alumina fulfils very high requirements as concerns chemical purity, hardness, crystallographic structure, degree of comminution and many other physieochemical features.Alumina is chiefly obtained by the dehydroxylation of aluminium hydroxides. The final aim is most often the manufacture of the most stable form of A1203 i.e. a-A1203, corundum. Corundum has exellent properties, such as high hardness, thermal resistance and high melting temperature. The final physicochemical properties of the produced ceramic material and the economy of the technological process of its manufacture depend on the rate of formation and the quantity of a-A1203.The dehydroxylation of aluminium hydroxides is a very complicated process. Numerous research works [1][2][3][4][5][6][7][8][9], have demonstrated this, though the conclusions are sometimes discrepant. The transformations of the structure of aluminium hydroxides during heating up to the formation of new crystalline products depend on many factors, such as the type and origin of the aluminium hydroxide, grain size, chemical purity, heating rate, calcination time, atmosphere, mineralizator additives and others. Irrespective of these factors, greater or smaller amounts of a-A1203 are always obtained if the calcination temperature is adequately high. The proposed schemes of dehydroxylation differ because of the various methods of manufacturing of John Wiley & Sons, Limited, Chichester Akaddmiai Kiad6, Budapest
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