Electrolytic manganese metal deposition process is cathode Mn products. Since the manganese potential is very negative (-1.18V), and the Mn 2+ hydrolysis pH Ó¨ 25 is 7.655, the pH Ó¨ 70 is 6.65. In order to increase the hydrolysis pH and improve the current efficiency, the electrolyte must maintain high (NH 4 ) 2 SO. 4 content, its role is: 1 the formation of manganese ligand ions, improve the pH value of Mn 2+ hydrolysis, so that Mn 2+ is not easy to hydrolyze, see Figure; 2 buffering; 3 increase the conductivity of the solution. The normal electrolysis operation cannot be maintained without adding (NH 4 ) 2 SO 4 .
The requirement of (NH 4 ) 2 SO 4 content is related to the use of antioxidants in electrolysis. For example, SeO 2 is used as an antioxidant, and the content of (NH 4 ) 2 SO 4 is 100-120 g/L, such as using SO 2 as an antioxidant. The dosage of (NH 4 ) 2 SO 4 needs to be 130~140g/L.
The main reaction formula of MnCO 3 ore leaching is MnCO 3 +H 2 SO 4 ===MnSO 4 +H 2 O+CO 2 ↑
Fe 3 O 4 +4H 2 SO 4 ===FeSO 4 +Fe 2 (SO 4 ) 3 +4H 2 O
FeO+H 2 SO 4 ===FeSO 4 +H 2 O
CuO+H 2 SO 4 ===CuSO 4 +H 2 O
CoO+H 2 SO 4 ===CoSO 4 +H 2 O
NiO+H 2 SO 4 ===NiSO 4 +H 2 O
MgO+H 2 SO 4 === MgSO 4 +H 2 O
Calculated according to the requirement of leaching solution containing Mn40kg/m 3 , the calculation formula of manganese carbonate ore powder is
The ratio of mineral acid to mass (mass ratio) of MnCO 3 ore fines is 1:0.55~0.6. Main technical conditions for leaching of MnCO 3 ore:
Temperature: 1 is not heated, the heat of H 2 SO 4 can be used to raise the slurry to 55~65 °C. 2 external heating to 80 ° C
Liquid to solid ratio: 8~10:1
Leaching acid: 70~80g/L
Leaching end point pH: 1.5
Leaching time: 2~3h
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