# Study of Oxidative-Reductive Potential Changes in the Enrichment of Oxidized Polymetallic Ores
## 4 Conclusions  
The oxidized ores of the Koskudyk deposit are characterized by a high degree of oxidation, fine dissemination, and specific structural-textual features, which classify them as finely disseminated and difficult-to-beneficiate ores.  
The studied ore sample contains 0.85% lead, 0.65% zinc, 5.4 g/t silver, and 0.6 g/t gold.  
According to the data from phase chemical analyses, the sample is classified as of the oxidized type. This is confirmed by the fact that oxidized compounds constitute 79.69% of the total lead mass, while for zinc, this value reaches 84.72%.  
The ore minerals in the sample are represented by dull ores, chalcosine, covellite, goethite, and hematite. Sulfides present include chalcopyrite, galena, pyrite, and sphalerite.  
Studies were carried out on the sulfidization of oxidized minerals with sodium sulfide, and the redox potential (ORP) levels were determined for each consumption rate. The high efficiency of preliminary sulfidization of ore using Na\({}_{2}\)S for the flotation of oxidized lead minerals has been experimentally confirmed. This approach significantly increases lead recovery compared to flotation without a sulfidizing agent (\(\varepsilon\) = 37.48%).  
It has been established that the redox potential (Eh) of the pulp significantly influences flotation performance. Maximum lead recovery (\(\varepsilon\) = 50.07%) is achieved at a redox potential of approximately -160 to -200 mV. Under more strongly reducing conditions (Eh below -200 mV), the efficiency of lead recovery declines (to \(\varepsilon\) = 48.04%). A redox potential of -200 mV corresponds to the optimal value reported in the literature. Maintaining this potential enhances the collectability of sulfide minerals and reduces the adverse effects of oxidized surface films on flotation efficiency. At the same time, changes in redox potential had virtually no effect on zinc recovery. Across all tested sulfidization regimes, zinc performance showed little to no improvement, confirming the limited effectiveness of this method in the beneficiation of oxidized zinc ores. As noted earlier, the flotation of oxidized zinc requires additional measures (e.g., the addition of auxiliary reagents, zinc hydrometallurgy, zinc activation, etc.).  
The results of this study have substantial scientific and practical significance. They deepen the understanding of electrochemical factors--particularly redox potential levels--that affect the flotation efficiency of complex and refractory oxidized polymetallic ores. These findings can serve as a foundation for developing more effective technologies for processing such challenging raw materials. Practical implementation of the proposed approaches may improve the recovery of valuable metals and enhance the overall economic efficiency of beneficiation.  
Conceptualization: T.T. and A.M.; methodology: G.M.; formal analysis: L.S.; investigation: A.M.; data curation: A.M. and L.S.; writing--original draft preparation: T.T.; writing--review and editing: T.T.; project administration: A.M., M.B. and K.R. All authors have read and agreed to the published version of the manuscript.  
The work was carried out within the framework of the grant project AR 23489765 and was funded by the Committee of Science of the Ministry of Education and Science of the Republic of Kazakhstan.  
Not applicable.  
The original contributions presented in the study are included in the article. Further inquiries can be directed at the corresponding authors.  
The authors state that the study was conducted in the absence of any commercial or financial relationships that could be interpreted as a potential conflict of interest.