Page 42 - Annual Report_21-22

HYDRO & ELECTROMETALLURGY

Recovery of Mn as EMD from low grade ores and secondaries for energy applications

India’s manganese ore deposits are predominantly low reductive acid leaching to recover Mn from low grade ores
grade which constitutes >60% of total reserves and and ferroalloy slags, instead of concentrated 99% SO gas
2
remains under-utilized due to very high iron content. in a novel approach. This approach makes concentrated
SO is well known reductant for its favourable kinetics in 99% SO redundant in the leaching of Mn. The electrolytic
2
2
leaching manganese,.However commercial SO (99.9%) manganese dioxide (EMD) produced subsequent to
2
are either imported or produced through a concentrator purification from the leach liquors from ferroalloy slag and
plant, making it energy and cost intensive to implement for low grade ores containing 10-20% Mn was found to satisfy
the production of Electrolytic Manganese Dioxide (EMD). and surpass quality criteria for battery applications as per
In the current project, low concentration SO produced BIS (IS11153:1996).
2
from typical sulphur burners, was successfully utilized in

Fig. Mn recovered as EMD from low grade ores by hydrometallurgical process using low concentration SO
2
as reductant.
Recovery of valuables from Spent Pot Lining carbon and bench-scale testing

NALCO generates Spent Pot Lining (SPL) from their smelters project involves hydrometallurgical processing of SPL
after the end-of-life of the individual smelter units. CSIR- to remove hazardous materials and recovery of carbon
IMMT has taken up a project from NALCO based on in- values. Presently, preliminary testing and laboratory
house R&D carried out at NALCO for the optimization of optimization of processing for the recovery of valuables
SPL utilization flow sheet and bench-scale testing. The from SPL is underway.

Fig. Hydrometallurgical processing of SPL for removal of hazardous constituents
40 ANNUAL REPORT 2021-22