Industrial mixers are equipment used to mechanically combine different types of materials in order to obtain homogeneous mixtures. In concrete industry production, mixers play a crucial role by facilitating the efficient and consistent blending of various constituents to create high-quality concrete. Because the mixers in the concrete industry work in conditions characterized by abrasive and erosive loadings, the authors of this paper tried to establish a dependence between the quality of the material from which the mixing elements are made and their wear resistance. Three types of cast irons alloyed with chromium, specific to the construction of mixing blades, were used in this research. The working environment was a mixture of crushed mineral aggregates corresponding to the granulometric class 4–8 mm. The tests were carried out on an experimental stand designed and built by the authors of this paper. The stand reproduces on a scale of 1:2 a drum made up of a double-axis horizontal mixer. The stand had the possibility to change the value of the attack angle of the mixing blades, corresponding to the following values: 30, 45, and 60 degrees. The results of the tests established the dependence between the type of material and the wear rate of the blades as well as the influence exerted by the angle of attack on the wear of the mixing blades. It was shown that when the inclination angle of the blade relative to the shaft axis increases, the cumulative mass loss decreases, with values between 43% and 55.83%, as a function of the quality of blade material.

The studies carried out address an important problem for the concrete and asphalt industry, referring to the wear phenomena that affect the elements (flights) of rotary dryers used to dry mineral aggregates. In this article, the authors propose a lifetime estimation method for rotary dryer flights. In order to benefit from greater credibility, the proposed method was applied based on the experimental results obtained, by the authors, in the laboratory, on a stand that reproduces a portion of the real equipment. Starting from these results, the authors identified the mathematical functions used to model the failure rates (wear) of the flights by referring to characteristic quantities for wear evaluation: mass loss of material; reduction in the thickness of the part; surface affected by wear. The experimental data—the input data for the proposed algorithm—correspond to six steels used in industrial applications. The wear phenomenon was modeled considering both the situation of uniform wear and the situation of differentiated wear on the flight surface. Therefore, the steel type with the highest service life values could be identified, namely, steel grades E and G. The method proposed in this paper can be extended to any category of material or part provided that the failure rate function is identified beforehand, possibly based on a laboratory experiment.

The flights of rotary dryers used for drying mineral aggregates face significant erosive-abrasive wear, affecting efficiency and maintenance costs. This study explores—by way of example—the possibility of using experimental measurements and statistical modeling to evaluate the wear mechanisms and the effect of covering the active surface of the flights with hard materials (welding deposits). The in situ thickness loss was measured on the active surface of the flights, in areas with and without deposits, after different periods of industrial operation (720 and 1118 h). The statistical analysis (Wilcoxon and Mann-Whitney U tests) aimed to assess the relevance of the measurements in a situation affected by a multitude of influencing factors, such as the situation of the wear of the rotary dryer flights. Finnie and Hutchings erosion models were used to predict wear behavior based on the impact velocity of mineral aggregates, incidence angles, and drum filling degree. The proposed methodology provides a predictive approach for optimizing rotary dryer maintenance and extending component life.

The asphalt industry, essential for the global transport infrastructure, requires substantial investments to increase the durability of production facilities. The quality of asphalt depends, essentially, on the degree of drying of mineral aggregates. Therefore, the rotary dryer is of major importance for ensuring the quality of asphalt. The rotary dryer flights are subjected to an erosive-abrasive wear process during operation, generated by the impact of abrasive aggregates. These phenomena lead to severe degradation of the flights. Experimental research, carried out by the authors, on-site, aimed at identifying solutions to improve the wear behavior of the flights, by hardfacing with four wear-resistant materials (FLUXOFIL 51, FLUXOFIL 56, SAFER R 400, SAFER R 600), using the GMAW and SMAW processes. The results revealed a decrease in the wear rate and a flattening effect of the wear curve along the profile of the flight. The research targeted the upper rear surface of the flights, which is predominantly affected by erosive-abrasive wear phenomena. The resistance to abrasive wear of the flights was improved by hardfacing with FLUXOFIL 51 wear-resistant tubular wire, resulting in the lowest wear rate, especially between the areas marked 14–26, which are the areas most affected during operation.