Magnetic enrichment of braunite-rich manganese ore at different grain sizes

Metamorphism of primary manganese deposits changes the oxi-hydroxide assemblage into a braunite-rich paragenesis. Braunite magnetic properties, together with the increase in grain size during metamorphism, can allow magnetic enrichment at gravel-sand grain size. Samples were collected from a manganese deposit in the Eskis¸ehir region of Turkey, where a metamorphic event changed mineralogy from an original Manganese (Mn) oxi-hydroxide and chert assemblage to a braunite-rich quartzite and also showed an increase in grain size as a result of metamorphism. These samples were first crushed to a fine grain size and braunite was collected using a magnetic separator. Results show that metamorphic braunite-rich manganese deposits can be successfully enriched at high Mn recovery with the best results in the þ1–10mm grain size range.