Maral Auyesbekova

Given the high energy intensity of the cement grinding process, the development of new and effective intensifiers is a pressing issue. The aim of this work is to develop grinding intensifiers from secondary raw materials produced during carpet manufacturing and gas processing wastes, and to study their effect on the structure and strength of modified cement stone. Methods of physicochemical analysis of raw materials and the obtained grinding intensifier, as well as standard methods for testing cement stone were used in the work. The possibility of obtaining an effective intensifier through the interaction of HYPAN (Hydrolyzed polyacrylonitrile) and diethanolamine was established. The optimal dosage of the grinding intensifier was determined to be 0.1%, which allows increasing the grade strength of modified cement stone by 31.2% and reducing the water consumption by 11%, which is explained by hydration due to the additional effect of reducing the electrokinetic potential between cement particles and increasing the fineness of cement particle grinding. Physicochemical analysis methods established that there is practically no free water in the modified cement stone sample and that the formation of the structure in the cement stone was achieved to a much greater extent. It has been established that, over time, the amount of C-S-H hydration products and calcium sulfoaluminate in the cement matrix of modified cement stone increases, which leads to an increase in the strength of the cement.

This article presents the results of a study exploring the potential use of gas processing waste as a raw material for synthesizing cement grinding intensifiers. Effective raw materials for synthesizing grinding intensifiers were identified: methyldiethanolamine (a gas processing waste) and hydrolyzed polyacrylonitrile (HIPAN) obtained from recycled nitrofiber. The use of alkanolamines as a raw material for synthesizing grinding intensifiers was substantiated. Physicochemical methods demonstrated the effectiveness of the methyldiethanolamine purification method. Optimal conditions for synthesizing grinding intensifiers were determined. Physicochemical analysis of the resulting grinding intensifiers revealed that all compositions exhibit a very strong C=O (amide) peak at 3300 cm⁻¹, a broad N-H elongation peak at 1236 cm⁻¹, and a strong C-N (amide III) elongation, which together confirm the clear presence of the amide group (-CONH-) required for grinding intensifiers. It was determined that the cumulative distribution curve of the product obtained with the addition of 0.25% of the synthesized grinding intensifiers G+M and G+T shifts toward finer grinding due to the unique combination of active components (alkanolamines, HIPAN), which allows them to act synergistically. HIPAN provides increased efficiency due to its high basicity, which reduces the electrostatic attraction between particles, leading to finer grinding and increased productivity.

This paper presents data on the synthesis of cement grinding intensifiers produced from oil and gas processing wastes, namely secondary alkanolamines. The results of physicochemical characterization of the raw materials are reported, including the optimal purification conditions for the wastes and the synthesis parameters of the grinding intensifiers, as well as the physicochemical properties of the obtained products. It was found that the optimal conditions for producing the grinding intensifier involve conducting the reaction at 45°C for 6 hours with a 1:9 component ratio. The effects of the synthesized intensifiers on the cement clinker grinding process were investigated, including their influence on particle size distribution and the mineralogical composition of modified cements. The particles of the modified cement were shown to exhibit a predominantly spherical morphology; the maximum laser diffraction value reached 13.5%, the intensity was 88%, and the particle size was mainly around 2 μm (more than 53.5%), while the fraction of particles within the 100-200 μm range was 4.87%. X-ray diffraction and differential thermal analysis revealed that hydration of the modified cement is accompanied by a slight decrease in the diffraction intensity of calcium silicate phases (C2S and C3S), whereas an increase in the diffraction intensity of calcium hydroxide (Ca(OH)2) was observed. This indicates the formation of calcium hydroxide and calcium silicate hydrate (C-S-H) during cement hydration. The diffraction peaks of these phases were detected within the ranges of 30-33° 2θ and 40-45° 2θ. In addition, the presence of aluminate (C3A) and ferrite (C4AF) phases within 40-45° 2θ corresponds to calcium carbonate (CaCO3) observed in low-intensity regions between 29.4° 2θ and 48.5° 2θ, which is associated with CO2 absorption from the atmosphere. These changes reflect phase transformations during hydration and the formation of phases that are critical for strength development. The optimal dosage of the grinding intensifier in the cement composition was determined to be 0.02 wt.% (based on dry residue).