Manganese ores are mainly classified into carbonate and oxide types. The carbonate ores are finely disseminated and complex in association, making them difficult to beneficiate; the oxide ores generally have higher grades and are often accompanied by iron, phosphorus, and other elements. The crushing and beneficiation flowsheets vary depending on the ore type.
Crushing Process: Three-Stage Closed-Circuit
To reduce the feed size for grinding and save energy, most manganese ores adopt a three-stage closed-circuit crushing flow:
Primary crushing: Jaw crushers are commonly used to break run-of-mine ore down to 100-300 mm. For very large-scale mines, gyratory crushers (with a capacity of over 2000 t/h) can be selected.
Secondary crushing: For high-hardness ores, standard cone crushers are preferred; for medium-hard or brittle ores, impact crushers or hammer crushers offer better cost-effectiveness. The secondary product is usually in the range of 25-50 mm.
Tertiary crushing: Short‑head cone crushers are used to reduce the material to the final required size, generally below 12 mm and often below 8 mm, to meet subsequent beneficiation requirements.
A vibrating screen is employed to close the circuit, with oversize returned to the tertiary crusher. This ensures a stable and fine feed for the grinding mill.
Beneficiation Process
Carbonate manganese ores: Mainly processed by high-intensity magnetic separation, dense-medium separation, and flotation. Ores containing carbonaceous matter or pyrite are treated by selective flotation to remove impurities; hydrothermal lead-zinc bearing ores use a flotation-magnetic separation combination; high-sulfur ores are roasted to eliminate sulfur; extremely refractory ores are sent directly to metallurgical treatment.
Oxide manganese ores: Gravity concentration is the primary method. Weathered oxide ores are first washed and deslimed; the cleaned product can be sold as concentrate or further upgraded by jigs and shaking tables. For lean sedimentary primary ores, dense-medium separation and jigging are used to discard gangue and obtain lumpy concentrate.
In summary, the beneficiation of manganese ores should be flexibly designed based on ore type, mineral association, and dissemination size, combining crushing, washing, gravity separation, magnetic separation, flotation, roasting, and other unit operations to achieve efficient resource utilization.
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