The circular economy for sustainable economic deployment is strongly based on the re-use of secondary products and waste utilization. In the present study, a new effective cementation method for recovering valuable metallic copper from industrial wastewater using Fe⁰ powders is reported. A high-speed mixer-disperser (HSMD) capable of providing a cavitation effect was used for the rapid intake, dispersion, and mixing of Fe⁰ powder in an acidic wastewater solution (pH ≈ 2.9) containing copper ions mainly in the form of CuSO₄. Three iron powders/particles were tested as the cementation agent: particles collected from industrial dust filters (CMS), water-atomized iron-based powder AHC100.29, and sponge-iron powder NC100.24. The effects of mixing regimes and related mixing conditions on the effectiveness of the Cu cementation process were evaluated by comparison between the HSMD and a laboratory paddle mixer. It was observed that the use of cavitation provided more efficient copper removal during the copper cementation process in comparison to the standard experiments with the propeller mixer. Under the cavitation regime, about 90% of copper was cemented in the first five minutes and the final copper removal of 95% was achieved using all three Fe⁰ powders after seven minutes of cementation. In comparison, only around 55% of copper was cemented in the first seven minutes of cementation using the traditional mixing method.

A mixture of an illitic clay and waste glass was prepared and studied during the sintering process. The illitic clay, from the Liepa deposit (Latvia), and green glass waste (GW) were disintegrated to obtain a homogeneous mixture. The addition of disintegrated GW (5–15 wt% in the mixture) led to a reduction in the intensive sintering temperature, from 900 to 860 °C, due to a significant decrease in the glass viscosity. The addition of GW slightly decreased the intensities of the endo- and exothermic reactions in the temperature range from 20 to 1000 °C due to the reduced concentration of clay minerals. GW reduced the plasticity of the clay and reduced the risk of structural breakage. The increase in sintering temperature from 700 to 1000 °C decreased the apparent porosity and water uptake capacity of the ceramics from 35% and 22%, down to 24% and 13%, respectively. The apparent porosities of all the sintered mixtures showed a decrease of between 6% to 9% after the addition of GW with concentrations from 5 up to 15 wt% respectively, while the water uptake capacities decreased from between 4% and 10%. The addition of GW led to an increase in the apparent density of the ceramic materials, up to 2.2 g/cm³. Furthermore, the compressive strength increased by more than two times, reaching a highest value of 240 MPa after the sintering of the 15 wt% GW-containing mixture at 1000 °C.

The increasing freight volumes and the speed of transport, as well as increasing demands with regard to safety have made the search and development of new anti-friction materials a topical task. The main requirements to the bearing assemblies include reliability, durability, simplicity and ease of maintenance. The paper considers the features of the manufacture of braking sliding sleeves/ bushings for transport vehicles made from sintered low-alloy powder materials based on Fe-C-Ni with Ni and Mo contents of 0.3%. The paper presents data on the microstructure of the sintered samples of the products and research of some physical and mechanical properties. Surface quality and friction coefficient were evaluated by surface profiling and tribological tests, correspondingly. Particular attention is paid to the use of ultrasonic testing for quality control of the products.

The method of magnetic pulse processing is used in the stamping of sheet metal and tube parts, welding and assembly operations. In powder metallurgy, the method is used for pressing powders, processing sintered powder products and transporting materials in various media. To increase the efficiency of the processing, electromagnetic field formers are used-field shapers that focus the field strength in a narrow working area. In this paper, the basic types of field shapers are considered: electromechanical, electrodynamical and magnetic. Their advantages and disadvantages are pointed out. The results of evaluation of magnetic induction of the inductors using field shapers made of cast bronze and powder materials are presented. Special attention is paid to a research of field shapers made of powder material known as SOMALOY material. The research provides recommendations for selection of parameters of the process of processing materials in a pulsed electromagnetic field and the design of technological devices and tools.