Grinding Capacity of Sulfated Clinkers

Introduction. The dispersion characteristics of cements largely determine their physical and mechanical properties, and for expansive cements, their deformation characteristics. Regulation of the dispersion characteristics of cements is achieved in various ways, including by changing the grain size distribution. The grain composition of cements depends on the grinding methods, the microstructure of the clinkers, as well as the microhardness of the minerals included in its composition, and their grindability. The purpose of the study is to determine the degree of resistance, grindability and energy consumption during grinding of an expanding additive in the form of sulfoferrite clinker. Materials and methods of research. This paper examines the grindability of sulfoferrite clinker as an expanding additive in comparison with Portland cement. Microhardness was determined as the degree of resistance of a material to destruction. The degree of clinker grindability was determined based on specific energy consumption, and studies were conducted on the distribution of particles of ground additive by fractions. The research methods are sieve analysis of ground powder, electron microscopy, and X-ray phase analysis. The Rosin-Rammler-Bennett equation was used to analyze the particle distribution based on particle size analysis data. The article concludes that the expansion additive in the form of sulfoferrite clinker is acceptable from the point of view of energy resource use. Results. For ferrous sulfated clinkers, difficult-to-grind sulfated ferrite minerals with a small specific sur-face area (Ssp=200 m2/kg) are concentrated in large and medium fractions. With an increase in the specific surface area to 300 m2/kg, the content of these minerals in the middle fractions increases. With a further increase in the specific surface area to 400 m2/kg, calcium sulfoferrites are mainly located in large (>80 μm) and small (<45 μm) fractions. When ground, silicates in this clinker are located at Ssp=200 m2/kg in the medium fractions, and with an increase in the specific surface area in the fine fractions. The characteristic particle size for sulfoferrite clinker (Ssp=400 m2/kg) was 35–37 µm. Conclusions. The article concludes that in order to obtain ferrous sulfated minerals of fractions 80-63 µm, it is necessary to grind sulfated clinkers to Ssp=300 m2/kg, and to obtain these minerals with a size of less than 45 µm, their finer grinding to 400 m2/kg is necessary.