Combined Beneficiation Process for Magnetite Ore

1. Raw Material Pretreatment

·         Crushing and Grinding: The raw ore is crushed and ground to a target particle size (typically with 50%–90% passing 0.074 mm) to achieve sufficient mineral liberation.

2. Deep Reduction Process

·         Mixing and Batching: Ore powder is mixed with a reductant (coal powder, particle size <2.0 mm) at a coal blending ratio of 1.5 (1.5 times the theoretical coal requirement), with 5% lime (CaO) added as a flux to adjust basicity.

·         Reduction Reaction: The mixture is reduced at 1275°C for 60 minutes, converting iron oxides into metallic iron particles while transforming gangue into separable silicate phases.

3. Separation Stage

·         Water Quenching and Crushing: The reduced product is water-quenched, dried, and crushed.

·         Stage Grinding-Magnetic Separation:

o    Primary Grinding: Material ground until 30%–60% passes 0.074 mm.

o    Two-Stage Magnetic Separation:

§  Roughing: Magnetic field intensity 143 kA/m for primary concentrate.

§  Cleaning: Magnetic field intensity 127 kA/m for purification.

4. Classification and Refining

·         Size Screening: Concentrate is classified by particle size:

o    Grade 1 Product (>0.160 mm): Iron grade 92%–95%, used for premium casting/powder metallurgy.

o    Grade 2 Product (0.106–0.160 mm): Iron grade 92%–95%, same as Grade 1.

o    Grade 3 Product (0.074–0.106 mm): Iron grade 80%–90%, as steelmaking additive.

o    Grade 4 Product (<0.074 mm): Iron grade 80%–90%, as ironmaking additive.

5. Tailings Treatment

·         Magnetic tailings (containing residual coal and silicates) are discarded or recycled.