## 3 Results and Discussion
### Results of the Two-Stage Counter-Current Acid Leaching with the Addition of Hydrogen Peroxide
Results of the Analysis of the Composition of Sludge Left after Single-Stage and Two-Stage Counter-Current Acid Leaching with the Addition of Hydrogen Peroxide  
Table 6 presents the results of analyses of battery masses and sludges formed after the single-stage leaching with the use of 20% sulfuric acid solutions and various volumes of hydrogen peroxide. Table 7, on the other hand, compares the results of analyses of battery masses and sludges obtained after the two-stage, counter-current leaching. Figures 3 and 4 also list selected X-ray diffraction patterns of the after-leaching sludges, in the case of single-stage leaching for Materials II and III, and in the case of two-stage leaching for Materials I and III. The analysis of the obtained results of single-stage leaching showed large differences in the composition of the individual tested battery masses. In all cases, the leaching of the targeted ingredients with the higher dose of hydrogen peroxide was more effective. For Material I, the battery mass remaining after the leaching contained <0.2% of cobalt and phosphorus and <0.1% of nickel, lithium, manganese, copper and iron, and the fluorine content in the sludge did not exceed 2.2%. In the case of Materials II and III, the composition results were similar. The battery masses remaining after leaching in these two cases contained <1.5% of cobalt when using the higher dose of hydrogen peroxide, and >7% when using the lower dose of hydrogen peroxide. In the case of nickel, lithium, manganese, copper, iron and phosphorus, such large differences were not observed when using different doses of aqueous hydrogen peroxide solution. However, the fluorine content did not exceed 1.5%. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Material**} & \multirow{2}{*}{**The Initial Weight of the Battery Mass of after-Leaching Sludge (g)**} & \multicolumn{6}{c}{**Composition of the Battery Mass or after-Leaching Sludge (\%)**} \\ \cline{3-11}  & & **Mas of after-Leaching Sludge (g)** & **H\({}_{2}\)O\({}_{2}\) (dm)\({}^{3}\)** & **Co** & **Ni** & **Li** & **Cu** & **Mn** & **Fe** & **P** & **F** \\ \hline \multirow{4}{*}{I} & 1000 & - & 9.33 & 9.83 & 3.64 & 2.73 & 8.70 & 0.31 & 0.84 & 3.22 \\ \cline{2-11}  & 431 & 1 & 0.15 & 0.16 & 0.09 & 0.09 & 0.13 & 0.15 & 0.31 & 2.15 \\ \cline{2-11}  & 413 & 2 & 0.08 & 0.09 & 0.06 & 0.06 & 0.06 & 0.09 & 0.17 & 2.16 \\ \hline \multirow{4}{*}{II} & 1000 & - & 29.70 & 1.96 & 3.79 & 1.53 & 0.81 & 0.39 & 0.49 & 1.84 \\ \cline{2-11}  & 457 & 1 & 7.23 & 0.08 & 0.34 & 0.08 & 0.08 & 0.33 & 0.20 & 1.18 \\ \cline{2-11}  & 391 & 2 & 1.42 & 0.05 & 0.12 & 0.11 & 0.01 & 0.21 & 0.20 & 1.33 \\ \cline{2-11}  & 1000 & - & 27.00 & 2.66 & 3.79 & 1.37 & 1.51 & 0.34 & 0.47 & 2.02 \\ \cline{2-11}  & 448 & 1 & 7.06 & 0.14 & 0.42 & 0.08 & 0.07 & 0.08 & 0.09 & 1.36 \\ \cline{2-11}  & 386 & 2 & 0.83 & 0.03 & 0.07 & 0.02 & \textless{}0.01 & 0.08 & 0.09 & 1.50 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparison of the results of analyses of the battery masses and sludges formed after the single-stage leaching.