The method of using of concentration plants tailings is proposed for the first time in this study. These tailings contain a number of valuable metals, such as Cu, Fe, Zn, etc. and are a potential raw material for obtaining concentrates of some elements. An electrohydropulse discharge is used to intensify the process of leaching of copper and other metals. Ammonium bifluoride, the most effective of the ammonium salts used in the copper leaching by the ammonization method, was chosen as a reagent. The influence of significant leaching parameters is studied and optimized using probabilistic deterministic planning of experiment. Based on the study findings, the following process conditions were found to be optimal: the mass ratio of S : L (solid : liquid) = 1 : 1; Cu : F = 1 : 6; sulfuric acid concentration - 40 g/l; the experiment duration - 30 min; discharge voltage - 10 kV and the leaching efficiency can be achieved 80-85 %. Comparative features of tailings samples from the Karagaily concentration plant (Republic of Kazakhstan) were studied using X-ray diffraction (XRD), scanning electron microscope (SEM), atomic emission spectral analysis. It was found that the copper minerals contained in the tailings are completely shattered and the copper is maximally transferred to the aqueous phase.

N-doped graphene is not only a promising metal-free catalyst, but also a convenient carrier of metal nanoparticles for the creation of effective catalysts. Graphitic carbon nitride (g-C3N4) is used more often in photocatalytic processes and less often as electrocatalysts. This paper describes the preparation of N‑containing carbon composites consisting of reduced graphene oxide (rGO) and g-C3N4 for the further creation of metal-carbon catalytic systems. These composites were prepared by the heat treating dry mixtures of graphene oxide (GO) and melamine (MA) in the temperature range of 450-550 °C in air. Oxygen-containing groups were identified in the graphene oxide samples synthesized by the modified Hummers method and in its reduced form. The thermogravimetric analysis method was used to determine the ranges of relative thermal stability of the GO + MA mixtures, which were found to be almost identical for the studied compositions with different component ratios. The structure of the graphene oxide and its composites with MA after heat treatment was studied by scanning electron spectroscopy, X-ray diffraction analysis, FTIR spectroscopy and elemental analysis. The effect of the ratio of the initial components on the formation of the heat treatment products was determined. It was shown that to obtain the rGO+g-C3N4 composites with a high content of carbon nitride, the ratio of the initial reagents should be taken equal to 1:2, and the heat treatment should be carried out at 550 °C.

In this work, for the first time, studies of the mineralogical composition and chemical semi-quantitative spectral analysis (SQSA) of the Zhezkazgan processing plant tailings before and after leaching were carried out. It was found that copper is present in the tailings in the form of the chalcosine and bornite minerals. After leaching with the use of ammonium bifluoride and a hydro-pulse discharge, chalcosine and boronite are destroyed, and copper passes into a solution containing phosphoric acid. As a result of multiple placing of tailings into the solution, the copper content in it is brought to a concentration at which copper deposition on a stainless steel plate is possible. The identification of copper was implemented on a LAES-Matrix grain spectrometer. A visual comparative analysis of the changes in the structure of the treated ore waste was carried out using a TESCAN MIRA scanning electron microscope. Metallic copper was obtained from solution by electrochemical reactions in an experimental laboratory setup as a result. The technology was developed on an experimental laboratory setup for the extraction of metallic copper and brought the choice of the solution medium and electrochemical processes to the stage of obtaining the target metal with a purity of 99.99 %

A probabilistic–deterministic design of experiments (PDDoE) approach was employed to optimize laser-induced breakdown spectroscopy (LIBS) parameters for the quantitative determination of minor components in lead-based alloys. The PDDoE optimization identified 18 J laser pump lamp energy, 1 µs delay, and 1 µs exposure as optimal conditions, minimizing spectral dispersion (5–8%) and ensuring stable plasma formation. The acquired spectra were subsequently processed in an R-based automated workflow, where Linear, Lasso, and Ridge regression models were used to establish quantitative relationships between normalized line intensities and atomic absorption spectroscopy (AAS) reference data. The resulting models demonstrated high accuracy (R² = 0.97 for Sn, 0.985 for Sb, 0.982 for Bi, 0.919 for As, and 0.905 for Ag), with prediction errors (RMSE) below 10% and limits of quantification (LOQ) under 0.05 wt.%. Principal component analysis (PCA) applied to 43 historical (19th–20th century) and technogenic samples (19th–20th century) allowed us to isolate clusters of Pb–Sb alloys corresponding to secondary accumulator materials, alongside a diffuse group of nearly pure Pb specimens containing variable minor impurities. The combined PDDoE–LIBS–R analytical framework provides a reproducible, non-destructive, and chemometrically validated methodology for the quantitative characterization and classification of archeological and industrial lead alloys.

This work involved conducting X-ray phase analysis and energy-dispersive spectroscopy (EDS), for the first time, as well as examining the kinetics of metal extraction processes from the tailings of the Zhezkazgan Concentration Plant (ZhCP) before and after their treatment. Based on the results of X-ray diffraction results, the main diffraction peaks have been found to corresponded to silicon-containing or silicate minerals, as well as phases characteristic of Cu2S, CuFe2S3, and ZnS. Following electrohydropulse discharge leaching, the silicates (SiO2) were partially destroyed, releasing metal oxides. The elemental composition of the tailings was analyzed using electron probe X-ray microanalysis. The EDS analysis revealed the presence of 13 elements, the most intense lines of which were silicon, oxygen, and aluminum, while the remaining elements were found in minor quantities. The activation energy was determined graphically using the Arrhenius equation based on the rate constants (lnK) at various temperatures and exposure times to electrohydropulse discharge. To determine the kinetics of the leaching process, a high-temperature thermometer was installed on the reactor to record the temperature of the slurry, including the solution reaction mixture. During the hydropulse discharge process, the temperature of the reaction medium rose to 60 °C over 30 minutes.