Magnesium salt removal from manganese electrolyte via low-temperature crystallisation

ABSTRACT

In the electrolytic manganese industry, magnesium accumulation in the electrolyte is detrimental to production systems. Therefore, in this study, magnesium was removed from manganese electrolytes via low-temperature crystallisation. The Mg²⁺ concentration was reduced from 43.00 to 23.33 g L^–1 at the optimal experimental conditions: crystallisation temperature of −5°C, crystallisation time of 1 h, H₂SO₄ concentration of 80 g L^–1, whereas the Mn²⁺ concentration was minimally affected. The resulting crystal products were primarily composed of Mg(NH₄)₂(SO₄)₂·6H₂O and a small amount of Fe(NH₄)₂(SO₄)₂·6H₂O. This process does not require the addition of a precipitant during crystallisation, therefore considerably reducing the magnesium removal cost and facilitating clean production.

KEYWORDS:

• Manganese electrolyte
• magnesium removal
• low-temperature crystallisation
• hydrometallurgy

Acknowledgments

This work was supported financially by the National Natural Science Foundation of China (Grant Nos. 51964029, 51804146), National Key Research and Development Plan Solid Waste Resources Special of China (Grant Nos. 2018YFC1900402) and Applied Basic Research Project of Yunnan Province of China (Grant Nos. 202001AT070079), for which the authors are sincerely grateful, and we gratefully acknowledge many helpful comments and suggestions from anonymous reviews.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Natural Science Foundation of China: [Grant Number 51964029]; National Natural Science Foundation of China: [Grant Number 51804146]; National key research and development plan solid waste resources special of China: [Grant Number 2018YFC1900402]; Applied Basic Research Project of Yunnan Province of China: [Grant Number 202001AT070079].