Manganese Ore Processing Methods and Equipment

Manganese ore is an important raw material for steel manufacturing, but there are few types of manganese ore with extraction value, so it is important to rationally process manganese ore, improve the recovery rate of manganese ore and reduce the tailings content. This guide examines proven processing techniques and equipment through the lens of mineral engineering expertise.

Manganese Ore Processing Methods and Equipment

Mining and Pre-Treatment of Manganese Ore

Extraction methods (open-pit or underground) depend on deposit geometry and depth. Post-mining, raw ore undergoes preparatory steps:

Washing: Removes clay and fines that hinder downstream processing.

Crushing/Screening: Multi-stage circuits (jaw → cone crushers) reduce ore to optimal liberation sizes. Vibrating screens segregate particles, preventing overgrinding.

Sampling/Blending: Ensures consistent feed quality via automated sampling and controlled stockpiling.

Core Beneficiation Strategies

Selection hinges on ore mineralogy, liberation characteristics, and gangue composition.

1. Gravity Concentration

Exploits density differences between manganese oxides/carbonates (3.3–4.5 g/cm³) and silicate gangue (2.6–2.7 g/cm³).

Equipment:

Jigs: Process 0.5–15 mm particles (e.g., trapezoidal jigs for coarse ore).

Spirals: Handle 0.075–5 mm fractions.

Shaking Tables: Target fines (0.04–3 mm).

Advantage: Cost-effective for coarse particle recovery, minimizing downstream grinding.

2. Magnetic Separation

Leverages weak paramagnetism in manganese minerals (susceptibility: ~100×10⁻⁶ cm³/g).

High-Intensity Roll Separators:

Carbonate ores: >480 kA/m fields.

Oxide ores: >960 kA/m fields.

Synergy: Often paired with gravity methods for carbonate ores to reject non-magnetic silicates.

3. Froth Flotation

Critical for fine-grained (<75 µm) or complex ores (e.g., rhodochrosite, Mn-oxide slimes).

Anionic Reverse Flotation:

Activators: Sodium silicate disperses slimes.

Collectors: Fatty acids (e.g., oleic acid) float carbonate gangue from manganese oxides.

Challenges: High reagent costs; typically combined with pre-concentration stages.

4. Pyrometallurgical Upgrading (Manganese-Rich Slag)

Addresses refractory ores with high P/Fe via selective reduction in blast/electric furnaces:

Process: MnO₂ → MnO (reduction at 950–1100°C), yielding slag with 35–45% Mn, <0.03% P.

Output: Ideal feedstock for ferroalloy production.

5. Hydrometallurgical Extraction

Reserved for low-grade/complex ores:

Acid Leaching (H₂SO₄): Dissolves Mn, followed by Fe/Al precipitation via pH adjustment.

Electrowinning: Produces 99.7% pure Mn from purified MnSO₄ electrolytes.

High-Purity Manganese Production

Electrolytic Manganese Metal (EMM):

Leaching: MnCO₃ + H₂SO₄ → MnSO₄ + CO₂↑ + H₂O.

Purification:

Oxidation: H₂O₂ oxidizes Fe²⁺ → Fe³⁺.

Neutralization: NH₃ precipitates Fe/Al hydroxides.

Sulfide Treatment: (NH₄)₂S removes Cu/Pb/Zn.

Electrolysis: Mn²⁺ + 2e⁻ → Mn⁰ (cathode: 99.8% purity).

Ferromanganese (FeMn) / Silicomanganese (SiMn):

FeMn: Submerged arc furnace (SAF) smelting of Mn ore + coke + Fe scrap (78–82% Mn).

SiMn: SAF processing of Mn ore + quartz + reductant (65–68% Mn, 16–20% Si).

Plant Design Considerations

A 300 TPD facility might integrate:

Comminution: Jaw crusher → Cone crusher → Ball mill.

Classification: Spiral classifiers → Hydrocyclones.

Separation: HGMS (high-gradient magnetic separators), Jameson cells, dewatering screens.

Water Management: Closed-loop thickener circuits minimize freshwater intake.

Economic & Sustainability Metrics

Recovery Rates: Gravity circuits achieve 55–65% Mn recovery; integrated flowsheets (gravity + magnetic + flotation) reach 75–85%.

Environmental Innovations:

Dry stacking of tailings reduces water consumption.

Slag valorization in cement production.

Bioleaching R&D for low-energy processing.

Market Specifications & Challenges

Typical Grades: Metallurgical ores >44% Mn; chemical grades >80% MnO₂.

Impurity Limits: Fe <5%, SiO₂ <10%, P <0.2%.

Key Hurdles: Processing fine-grained ores, reducing energy intensity, and meeting stringent emission standards.

Manganese beneficiation demands tailored approaches based on deposit geology and market needs. While gravity and magnetic methods dominate, hybrid circuits increasingly combine physical separation with hydrometallurgy for complex ores. Advances in sensor-based sorting and reagent chemistry promise enhanced recoveries, particularly for marginal resources. As decarbonization drives demand for high-grade Mn in batteries and alloys, sustainable processing innovations will define the sector’s future.