SEPARATION OF ZINC FROM MANGANESE BY SOLVENT EXTRACTION FROM ACIDIC LEACHATES OF SPENT ZINC-MnO2 DRY CELLS USING NEUTRAL ORGANOPHOSPHORUS EXTRACTANTS

Abstract

This paper describes a route for recovering manganese and zinc from spent zinc-MnO 2 dry cells via acid leaching using sulfuric or hydrochloric acids as leachants. Hydrogen peroxide was added as reductant. Experiments were run at 25-40 o C for 1-3 h. Under the best optimal conditions, over 97.5 wt.% of zinc and manganese were leached by both acids. Zn(II) was best extracted at high free acidity (≥ 1 mol L -1 ) with tributylphosphate (TBP) or trialkylphosphine oxides (Cyanex 923) diluted in n-heptane. Cyanex 923 was a better extractant than TBP, and the extraction was better performed in hydrochloric leachates. Mn(II) was more co-extracted from hydrochloric leachates and when Cyanex 923 was the extractant, but was easily scrubbed with dilute leachant (~1-2 mol L -1 ). Zn(II) striping was possible using 5 mol L -1 HCl or H 2 SO 4 . Manganese was precipitated as oxalate (MnC 2 O 4 .2H 2 O), free of leached contaminants. High-purity sodium salts of the anions of the leachants were recovered after slow evaporation of the final solution.

Resource Recycling of Mn-Rich Sludge: Effective Separation of Impure Fe/Al and Recovery of High-Purity Hausmannite

“…When the sludge was dissolved in hydrochloric acid, an acidic leachate was generated, where more than 98% Mn was recycled as hausmannite with a Mn content of 63.6% after the separation of Fe/Al via a hydrothermal route. Even though Fe/Al reacted with an extractant to cause pollution, Cyanex 923 was used to be an extractant with acid leaching and chemical precipitation method, in which 97% Mn was recycled . Ong et al employed H 2 SO 4 and H 2 O 2 leaching Mn and then precipitated Mn as MnO 2 with the addition of exogenous KMnO 4 , where KMnO 4 was residual in the rest solution and should be further removed.…”

“…Even though Fe/Al reacted with an extractant to cause pollution, 49 Cyanex 923 was used to be an extractant with acid leaching and chemical precipitation method, in which 97% Mn was recycled. 47 Ong et al employed H 2 SO 4 and H 2 O 2 leaching Mn and then precipitated Mn as MnO 2 with the addition of exogenous KMnO 4 , 5 where KMnO 4 was residual in the rest solution and should be further removed.…”

Extraction and separation of potassium, zinc and manganese issued from spent alkaline batteries by a three‐unit hydrometallurgical process

“…35 Whereas Ibiapina et al observed a ƞ leaching of 99.9% for Zn and 97.3% for Mn using H 2 SO 4 4.5 M and with H 2 O 2 0.59 M as the reducing agent at room temperature (25 °C). 34 Effect of the temperature Table 3 shows the ƞ leaching for Zn and Mn for both acid and acid reductive leaching using a 2 M H 2 SO 4 solution at 25, 40 and 60 °C and adding H 2 O 2 at a concentration of 0.8 M. Results show that the temperature had no effect on the ƞ leaching for Zn and Mn. The overall ƞ leaching for Zn an Mn was 99.6 ± 0.3 (wt.…”

“…36 and H 2 O 2 , but these studies extracted all the metals in only one leaching. 34,35 Effect of the solid to liquid (S/L) ratio Figure 7 shows the effect of the S/L on Zn and Mn extraction for both acid and acid reductive leaching. The S/L ratios were 1/5, 1/10 and 1/20 (g of BM/ mL of acid solution), in a 2 M H 2 SO 4 solution at room temperature and with the addition of H 2 O 2 0.8 M. The 1/5 (g of BM/ mL of acid solution) S/L ratio led to the best ƞ leaching for Zn and Mn (99.6 ± 0.4 (wt.…”

“…%) using H 2 SO 4 0.6 M when the concentration of H 2 O 2 increased from 0 to 0.85 M at 55 °C and S/L of 1/30 (g of BM/ mL of acid solution). 28,34 Almost all the Zn was extracted in the acid leaching step; only small amounts of residual Zn were completely extracted in the acid reductive leaching after the addition of H 2 O 2 . In this 3rd step, the highest amount of Zn leached was 8.7 ± 0.1 (wt.…”