# Study of Oxidative-Reductive Potential Changes in the Enrichment of Oxidized Polymetallic Ores
## 3 Results and Discussion
This is a significant improvement over Test 1\({}^{\prime}\)s 37.48% and indicates that sulfidization successfully rendered a substantial portion of the oxidized lead minerals floatable. The ORP measured in Test 4 was around \(-200\) mV (Ag/AgCl reference). This ORP level (approximately \(-200\) mV) appears to be optimal for maximizing lead flotation in our experiments. It is in good agreement with values reported in other studies for effective sulfidization-flotation of oxidized lead minerals [9; 12; 18; 19; 20; 21]. Maintaining the pulp potential in a moderately reducing range likely ensures the formation of a stable PbS film on the particle surfaces without causing excessive colloidal sulfur. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Consumption of Na\({}_{2}\)S (g/l) and Redox Potential (mV)** & **Product** & **Yield, \%** & \multicolumn{2}{c}{**Content, \%**} & \multicolumn{2}{c}{**Recovery, \%**} \\ \cline{4-7}  & & **Zn** & **Pb** & **Zn** & **Pb** \\ \hline \hline \multirow{8}{*}{800 (\(-260\))} & \multicolumn{2}{c}{Test 5} & & & & \\ \cline{2-7}  & Concentrate-1 & 4.08 & 1.42 & 8.86 & 8.28 & 40.18 \\ \cline{2-7}  & Concentrate-2 & 1.30 & 1.75 & 5.44 & 3.24 & 7.86 \\ \cline{2-7}  & \(\Sigma\) Concentrate & 5.38 & 1.50 & 8.03 & 11.52 & 48.04 \\ \cline{2-7}  & Tailings & 94.62 & 0.66 & 0.49 & 88.48 & 51.96 \\ \cline{2-7}  & Total & 100.0 & 0.70 & 0.90 & 100.0 & 100.0 \\ \hline \hline \multirow{8}{*}{900 (\(-310\))} & \multicolumn{2}{c}{Test 6} & & & & \\ \cline{2-7}  & Concentrate-1 & 5.42 & 0.97 & 6.73 & 7.49 & 40.52 \\ \cline{2-7}  & Concentrate-2 & 1.06 & 1.97 & 5.15 & 2.98 & 6.06 \\ \cline{2-7}  & \(\Sigma\) Concentrate & 6.48 & 1.13 & 6.47 & 10.47 & 46.58 \\ \cline{2-7}  & Tailings & 93.52 & 0.67 & 0.51 & 89.53 & 53.42 \\ \cline{2-7}  & Total & 100.0 & 0.70 & 0.90 & 100.0 & 100.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: _Cont._  
Figure 4: Results of the beneficiation efficiency calculation using the Houcock–Luyken (or Hankok–Luyken) formula. It should be noted that sulfidization does not significantly improve the enrichment results for zinc. It is known that additional measures are required for the flotation of oxidized zinc. such as the following [17, 22]:  
- Activation of zinc minerals using copper sulfate after sulfidization. - Flotation with other collectors--for example, fatty acids are often used for carbonate zinc minerals. - Hydrometallurgy of zinc. Besides pulp sulfidization, there are combined methods aimed at improving the flotation of oxidized ores. These methods include [9, 22, 23] the following:  
- Mechanochemical sulfidization--grinding oxidized ore with elemental sulfur. - Sulfidization roasting--roasting oxidized concentrates with the addition of sulfidizing agents followed by flotation. - Electrochemical sulfidization. According to current results, flotation of oxidized ores with sodium sulfide enables the extraction of approximately 50% of the lead content in a single stage. Chinese researchers achieved a lead concentrate recovery of 57% by employing microwave roasting with pyrite followed by flotation. [PERSON] and colleagues proposed a method of sulfidization roasting followed by flotation. [PERSON] and colleagues conducted laboratory studies on joint roasting of oxidized lead-zinc ores with pyrite-containing ores [22, 23]. Comparing these methods, it should be noted that chemical sulfidization in pulp (our case) offers advantages such as simplicity and low energy consumption, but it is limited to a recovery rate of around 50%. Combined methods (mechanochemical and thermal) potentially achieve more complete conversion of oxidized minerals to sulfides and higher recoveries but require additional processing stages (grinding with sulfur and/or roasting), thus complicating the technology. Hydrometallurgical methods (leaching zinc from tailings) can supplement flotation, providing nearly complete recovery of lead and zinc. However, this divides the process into two distinct branches--fotation for lead and hydrometallurgy for zinc.