# Study of Oxidative-Reductive Potential Changes in the Enrichment of Oxidized Polymetallic Ores
## 2 Materials and Methods  
The object of study is the oxidized lead-zinc ores from the Koskudyk deposit in Kazakhstan. The material composition of the ore and enrichment products was determined using the group trial gravimetric analysis method in representative samples specially prepared for atomic absorption analysis, atomic emission analysis, classical chemical analysis, and photometric analysis. The phase composition was determined using a D2 Phaser diffractometer from Bruker. The study of ore minerals was conducted in reflected light on polished thin sections using the OLYMPUS BX 53 microscope (Olympus Corporation, Japan), the SIMAGIS XS-3 CU (Olympus Corporation, Tokyo, Japan) video camera, and Mineral C7 (Siams, Yekaterinburg, Russia) image analysis software from SIAMS. For the research, a sample of ore from the Koskudyk deposit was delivered to the laboratory. After natural air drying, the sample was crushed to a size of 2 mm, homogenized using the 'cone and ring' method, and analyzed for the content of major components according to particle size classes. According to Table 1, the ore sample contains 0.85% lead, 0.65% zinc, 5.4 g/t silver, and 0.6 g/t gold. According to the data of the phase chemical analysis, the sample is classified as the oxidized type. This is confirmed by the fact that oxidized compounds make up 79.69% of the total lead mass, while for zinc, this value reaches 84.72%. The X-ray phase composition of the ore sample is shown in Figure 1, and the data in numerical form are presented in Table 2.  
The ore minerals in the sample are represented by dull ores, chalcosine, covellite, goethite, and hematite. Sulfides present include chalcopyrite, galena, pyrite, and sphalerite. \begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Component** & **Cu** & **Pb** & **Zn** & **Fe** & **CaO** & **MgO** & **As** \\ \hline Mass Fraction, \% & 0.02 & 0.90 & 0.70 & 6.42 & 1.33 & 3.35 & 0.023 \\ \hline Component & SiO\({}_{2}\) & Al\({}_{2}\)O\({}_{3}\) & Au, g/ton & Au, g/ton & Na & S total & K \\ \hline Mass Fraction, \% & 55.23 & 26.34 & 0.51 & 6.1 & 0.48 & 0.17 & 3.1 \\ \hline \end{tabular}
\end{table} 
Table 1: Chemical composition of polymetallic ore.  
Sphalerite contains fine inclusions of chalcopyrite (0.003-0.01 mm) and galena (0.005-0.05 mm) (Figure 2). Galena films with a thickness of 0.003-0.005 mm are observed along the contours of sphalerite grains, with inclusions of covellite (0.011-0.03 mm). Galena veins range in length from 0.01 to 0.30 mm. Along the contours of the sphalerite grains, there are galena films (0.003-0.010 mm) and covellite inclusions (0.03 mm). Rare sphalerite veins have a thickness of 0.18 mm. Occasional galena crystals measuring 0.15 mm and discontinuous galena veins with a thickness of 0.02 mm are also observed. The oxidized ores of the Koskudyk deposit are characterized by a high degree of oxidation, fine inclusions, and specific structural-textural features, which classify them as finely disseminated and difficult-to-beneficiate ores. The granulomatous (particle size) composition of the crushed ore (prepared to <2 mm) was analyzed, and the distribution of zinc and lead by size class is presented in Table 3. The sample was sieved into size fractions from 2 mm to below 0.045 mm, and each fraction was weighed (yield% of total) and assayed for lead and zinc. The recovery of metals in each size class was then calculated.