Vpliv procesa klinkerizacije na mineraloške lastnosti belitno-sulfoaluminatnih klinkerjev

Nagode, Klara (author), Dolenec, Matej (mentor), Kramar, Sabina (co-mentor)

Običajni portlandski cement dosega ugodne mehansko-fizikalne lastnosti z uporabo lokalnih surovin ter nizkimi stroški proizvodnje. Kljub vsemu se za nastanek cementa potrebuje veliko energije, proces klinkerizacije pa povzroči visoke izpuste CO2. Zato se raziskave na področju cementne industrije usmerjajo v iskanje in razvoj nizkooenergijskih veziv ter veziv z nizkim ogljičnim odtisom. Ena v vrsti alternativnih oblik je belitno-sulfoaluminatni cementni klinker, katere glavne faze so belit, yeelimit, ferit in anhidrit. Namen magistrske naloge je bil raziskati, v kolikšnem obsegu lahko nadomestimo primarne surovine s sekundarnimi in kako le-te ter procesni parameter (temperatura) vplivajo na lastnosti belitno-sulfoaluminatnih klinkerjev. Za potrebe raziskave so bili pripravljeni klinkerji treh različnih sestav z različnim deležem glavnih faz ter štirih različnih serij z različnimi vhodnimi surovinami. Kot sekundarni surovini smo uporabili pepel z rešetk in rdeči mulj, medtem ko je bila ena serija pripravljena iz naravnih surovin, druga pa iz analitsko čistih kemikalij. Homogenizirana surovinska moka je bila žgana pri temperaturah 1150 °C, 1200 °C in 1250 °C. Fazna sestava klinkerjev je bila določena z rentgensko praškovno difrakcijsko analizo ter s kvantitativno Rietveldovo analizo, mikrostruktura in vključevanje tujih ionov v glavne faze klinkerjev z vrstično elektronsko mikroskopijo z energijsko disperzijsko spektrometrijo. Z analizami smo potrdili, da so pri žganju poleg v izračunu predvidene glavne faze klinkerjev (belit, yeelimit, ferit in anhidrit) nastale tudi nekatere manj zastopane faze (ternesit, periklaz, perovskit, kalcijev aluminat in prosto apno). Iz rezultatov je razvidno, da se z naraščajočo temperaturo delež yeelimita in ferita spreminja zelo malo, medtem ko delež belita in anhidrita narašča. Na njun nastanek močno vpliva tudi faza ternesit, ki se ji delež niža z naraščajočo temperaturo. Mikrostruktura je v seriji iz analitsko čistih surovin podobna, medtem ko se v vzorcih iz naravnih surovin ter z dodanimi sekundarnimi surovinami spreminja, kar je posledica vključevanja tujih ionov (NaO, K2O, MgO).

• Language: Slovenian
• Keywords: cementni klinker, belitno-sulfoaluminatni klinker, pepel z rešetk, rdeči mulj, mikrostruktura klinkerja
• Work type: Master's thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2019
• PID: 20.500.12556/RUL-109970
• COBISS.SI-ID: 1526622
• Publication date in RUL: 11.09.2019

Secondary language

• Language: English
• Title: The effect of clinkerization process on mineralogical properties of belite-sulfoaluminate clinkers

Abstract

Ordinary Portland cement presents favourable physico-mechanical properties with use of local raw materials and low production costs. Nevertheless, cement industry consumes a lot of energy and the clinkerization process causes high CO2 emissions. Therefore, there is a burgeoning interest in the development and characterization of cement, which could reduce the energy used in production of cement clinker and the associated greenhouse gas emissions. One method of reducing the environmental impact is the use of the alternative binders such as belite-sulfoaluminate clinkers (BCSA), the main phases of which are belite, ye'elimite, ferrite and anhydrite. The aim of the master's thesis was to investigate to what extent the primary raw materials can be replaced by the secondary ones, and how these and process parameter (temperature) affect the properties of belite-sulfoaluminate clinkers. For the research, clinkers of three different assemblies with different range of main phases and four different series with different input materials were prepared. As the secondary raw material, bottom ash and red mud were used. Homogenized raw materials were burned at 1150 °C, 1200 °C and 1250 °C. The phase composition of clinkers was determined by X-ray powder diffraction analysis and quantitatively by Rietveld's analysis, while microstructure and the integration of foreign ions into the main phases of clinkers by Scanning Electron Microscopy with Energy Dispersive Spectroscopy. The analyses confirmed that during the clinkerization in addition to the predicted main phases of clinkers (belite, ye'elimite, ferrite and anhydrite), some of the minor phases (ternesite, periclase, perovskite, calcium aluminate and free lime) were formed. Results showed that with increasing temperature the amount of ye'elimite and ferrite does not change significantly, while the amount of belite and anhydrite increases. Their formation is strongly influenced by the phase ternesite, which decreases the amount with increasing temperature. The microstructure is similar in the analytically pure raw material series, while it changes in clinkers from natural raw materials and with the addition of secondary raw materials, resulting from incorporation of foreign ions (NaO, K2O, MgO).

• Keywords: cement clinker, belite-sulfoaluminate clinker, bottom ash, red mud, microstructure of clinker