Application of varieties of technogenic raw materials in cement technology

Abstract

The possibility of manufacturing a mineral binder using large-tonnage waste from other industries has been studied. The object of the research are mixtures for the manufacture of cement clinker based on systems of chalk – clay – scope of paper production and chalk – clay – husks of rice processing. At the same time, urgent tasks of developing the raw material base for cement production and resource conservation were solved. The development of new initial mixtures was carried out taking into account the peculiarities of the chemical and mineralogical composition of varieties of technogenic raw materials. According to the chemical composition, rice alkali is characterized by a content of 15.6 wt. % SiO2 with a large quantitative ratio of SiO2:Al2O3=65.2 and a small amount of alkaline earth and alkaline oxides. Scop differs from alkali in a large amount of CaO (25.8 wt. %), a lower content of SiO2 at a quantitative ratio of SiO2:Al2O3=1.3. In this case, there are quantitative ratios of oxides CaO:SiO2=2.5, CaO:Al2O3=3.3, CaO:SiO2:Al2O3=3.3:1.4:1, which determine the probable phase transformations during firing. The main rock-forming mineral in rice husks is amorphous silica; Scope is marked by the presence of crystalline phases of calcite, quartz, and kaolinite. The analysis of the possible content of the studied wastes and the determination of the compositions of the raw mixtures were carried out using the computer program «Clinker». Analysis of computer calculations and experiments indicates the possibility of reducing by 11–16 wt. % consumption of natural raw materials in the composition of mixtures for the manufacture of clinker in comparison with the known production composition. According to X-ray phase analysis, the features of the development of crystalline phases during the firing of mixtures using varieties of technogenic raw materials at a maximum temperature of 1400 ºС were established. Based on the data of technological testing, the differences in indicators of binding properties were determined - the setting time of cement when used in the composition of raw mixtures of rice husk and paper scope.