Coke-based carbon sorbent (CBCS) was produced using special coke fines with the following characteristics: ash, 4.5%; iodine adsorption capacity, 52%; specific surface area, 600 m² g⁻¹; and total pore volume, 0.4 cm³ g⁻¹. Gold adsorption from real production cyanide solutions in batch and column laboratory experiments was studied. The optimum adsorbent/solution ratio was 0.2 g/20 cm³. Sorption equilibrium occurred after 60 min of phase-time contact. The CBCS maximum adsorption capacity for gold was found to be 1.2 mg g⁻¹. Both the Langmiur and Freundlich isotherm models confirmed that gold adsorption by CBCS proceeds favorably, but the Freundlich isotherm best describes the adsorption equilibrium. The CBCS dynamic exchange capacity (100 g t⁻¹) and full dynamic exchange capacity (4600 g t⁻¹) for gold were determined in column tests. It was revealed using SEM that adsorbate was retained in sorbent pores. The possibility of completely eluting gold from CBCS was demonstrated. A CBCS pilot test to recover gold from 200 dm³ of the cyanide solution containing (mg dm⁻³) 2.6 Au, 0.42 Ag, and 490 Cu was carried out. The total amount of noble metals (Au + Ag) adsorbed was 99.99% and gold ions was 94%. The CBCS maximum adsorption capacity for gold reached 2900 g t⁻¹.

This article presents a study on the precipitation of copper from the cyanide leaching solutions used for gold–copper ores, both with and without the addition of a sulphidizer (Na₂S). Mathematical models were developed to summarize the effects of the pH, initial copper concentration, and Na₂S stoichiometric ratio on the precipitation process, using an experimental design based on a probabilistic–deterministic method. Varying the stoichiometric ratio of Na₂S has a minimal impact on the precipitation process. However, the presence of a sulphidizer is significant, as the precipitation process occurs at pH levels of 5 and below. The initial concentration of copper in the solution was identified as the most significant factor. At copper concentrations of 0.34% and 1.55% (pH = 3), the precipitation rates were 51.48% and 47.6%, respectively. This study also determined that the most effective method across the entire range of copper concentrations in the solution was the precipitation of copper in the form of copper cyanide hydrate (CuCN∙nH₂O) without the addition of Na₂S. At copper concentrations of 0.34% and 1.55% (pH = 3), the precipitation rates were 86.47% and 85%, respectively. The pH level was the most significant factor influencing this process, as copper deposition without Na₂S did not occur at a pH of 5. The obtained models allow us to accurately predict the influence of factors on the deposition process. Aided by the mathematical model of precipitation (without Na₂S), we selected the conditions for an enlarged experiment using 20 L of solution (Cu = 0.34%, pH = 3.2), which showed the high efficiency of the method. The calculated recovery amounted to 86%, where practical recovery was 87.2%, and divergence was ≥1.2%.

Although the mineralogical form of occurrence of critical metals is widely recognised as a key factor controlling their recovery during beneficiation, this relationship has rarely been verified directly on freshly mined ore and its primary beneficiation products from Central Asian polymetallic deposits. This raises the research question of how the mineralogical mode of occurrence of Bi, In, Cd, Co, Se, Te and Re governs their distribution between gravity and flotation products. Accordingly, the aim of this study was to establish how the mineralogical form of occurrence of these critical metals determines their distribution among gravity-concentration and flotation products, using ores from the Zhuantobe and Strezhanskoe deposits (Kazakhstan) as a case study. To this end, the mineralogical features and distribution patterns of critical metals during gravity and flotation beneficiation of polymetallic ores from these deposits were investigated by optical microscopy, X-ray diffraction, and SEM-EDS, while metal distribution among beneficiation products was determined by chemical analysis. Sphalerite, galena, pyrrhotite, and silver tellurides were identified as the main carriers of the critical metals, with bismuth occurring as an isomorphic admixture in sphalerite (3.69 wt.%) and galena (1.85 wt.%). During flotation, distribution was governed by mineralogical affinity: cadmium and indium were preferentially concentrated in the zinc concentrate (56.31% and 15.44% recovery, respectively), bismuth in the copper–lead concentrate (23.03%), and selenium and rhenium in the copper-bearing products (23.60% and 37.05%). Correlation analysis of the gravity-concentration products confirmed a close association of cadmium with sphalerite (R² = 0.9998), bismuth with galena and sphalerite (R² = 0.9674), and cobalt with iron-bearing sulfides (R² = 0.9144). These results demonstrate that the distribution of critical metals is governed primarily by their mineralogical form of occurrence rather than by bulk ore content, providing a basis for technologies for the complex processing of polymetallic ores.

The growing demand for critical metals associated with the global energy transition has increased interest in their potential recovery as by-products of copper processing. This study investigates critical- and associated-element deportment in ores and flotation products from three Kazakhstan deposits representing contrasting ore-system types: the Aktogay and Bozshakol porphyry Cu–Mo deposits and the Severny Samombet Cu-skarn deposit. Bulk geochemistry, optical mineralogy, SEM–EDS observations, and technological mass-balance data were integrated to evaluate mineralogical associations and element recovery into Cu and Mo flotation products. The two porphyry systems show comparatively selective deportment: Re preferentially reports to the Mo concentrates, with recoveries of 4.05% at Aktogay and 19.03% at Bozshakol, whereas Se preferentially reports to the Cu concentrates, reaching 55.35% and 27.18%, respectively. SEM–EDS observations of Aktogay molybdenite provide mineral-scale compositional evidence for Re-bearing molybdenite. In contrast, the Severny Samombet Cu concentrate shows broader multi-element recovery, particularly for Ag (86.00%), In (74.82%), Zn (68.15%), and Cd (55.04%), accompanied by intermediate recovery of Pb, Co, and Bi. Mineralogical observations reveal a heterogeneous sulfide assemblage together with discrete Bi–Pb- and Ag–Te-bearing accessory phases. Ge shows consistently low recovery into the investigated concentrates, including only 1.31% into the Severny Samombet Cu concentrate, indicating that bulk enrichment does not necessarily translate into flotation recovery. These results demonstrate contrasting critical-element deportment patterns among the three investigated deposits and show that evaluation of potential by-products requires integration of mineralogical characteristics with quantitative flotation-product recoveries. The results provide a basis for identifying technological streams warranting further assessment for critical-metal recovery, while quantitative determination of trace-element partitioning among individual mineral hosts requires mineral-specific analytical methods.