Mbuyu Ntunka1,2 and Brian Loveday1
1Discipline of Chemical Engineering, Howard College Campus, University of KwaZuluNatal, Durban 4001, South Africa
2Department of Chemical Engineering, Faculty of The Built Environment, Durban University of Technology, PO Box 1334, Durban 4000, South Africa
Novel method was investigated to reduce power consumption and pollution when producing electrolytic manganese dioxide from manganese oxide ores, high or low-grade. A material balance was performed on the designed flowsheet to check the feasibility of using recycled streams.
The use of bags around the anodes makes it possible to utilize the iron in the feed as a recyclable reductant for the dissolution of manganese ores.
Electrolysis in bags of purified manganese sulfate solution at the anode and regeneration of ferrous iron at the cathode are promising to sensibly reduce the electrolytic cell voltage, hence the power consumption.
With the rapidly growing demand for manganese products, a low-cost, environmentally friendly hydrometallurgical process needs to be developed to process high-grade, low-grade manganese ores, and secondary manganese resources. It is becoming increasingly unsustainable in many situations to use high-grade manganese ores (<40%), which are usually used for conventional pyrometallurgical processes or pyro-pre-treatment (roasting), because of the high carbon-foot print and high operational costs. In recent years, various hydrometallurgical processes have been studied and developed for the recovery of manganese from other manganese sources (Zhang and Cheng, 2007). However, no research has ever looked at the idea of regenerating ferrous iron at the electrowinning stage, instead of the hydrogen evolution reaction, recycle it with the effluent rich in sulphuric acid and be used as a reductant agent at the leaching stage.
This paper aims to develop a conceptual flowsheet of a novel low-cost and environmentally friendly hydrometallurgical process for the production of electrolytic manganese dioxide. The flowsheet includes applications of treatment strategies to minimize capital and operating costs.