Holistic Recycling of Red Mud for Recovery of Alumina, Iron, Rare Earth oxides, Titania with Utilization of Final Residue

>85-99% recovery of Alumina, Iron, Rare earth oxides (REOs) and Titania from red mud. For generic value, an estimate of 100kg of red mud upon processing by this technology generates 10.5 kg Alumina, 35.8 kg pig iron, 42 gram of REOs, 2.15kg TiO₂ and 16.7kg geo-polymeric products .

The red mud was processed by alkali roasting-water leaching to extract alumina (75-82%) and the residue was smelted to recover pig iron (95% recovery with 98% Grade). The remaining slag was processed in two stages to recover REEs and Ti in solution. The resultant PLS were processed individually by sequential precipitation to generate REOs (90.34%) and TiO₂ (89.34%). The final residue generated was geo-polymerised to obtain products with 18-20 MPa compressive strength. The process developed on lab scale were tested at 10-200kg scale.

Salient Technical Features:

• 75-82% alumina recovery in liquor
• 95% recovery of iron (>98% grade)
• 55-65% and 72-80% enrichment of REEs and titania in slag.
• Two-stage process for recovery of REEs and Ti
• 95% REEs extraction (99% Sc, 92% Ce, La and 88-90% Nd, Y).
• >90.34% pure REOs (10.6% La, 18.73% Ce, 4.15% Sc, 2.3% Nd, 1.07% Y, 0.04% Pr, 0.047% Ti and 0.67% total of Ca, Al, Fe) with 94.48% recovery.
• 86% Ti extracted in solution
• >89.53% TiO2 product (54.2% Ti, 13.52% Ca, 0.032% Al, 0.014% Fe, 3.774% S, 0.042% Si and 0.2% Na).
• 18-20 MPa geo-polymers from final residue
• 79 kWh energy consumption for 100kg
• Al, Fe, REE and Ti feed  suitable for industrial applications

Technology can extract critical elements like La, Ce, Sc, Nd, Y and Ti as salts in most desired marketable form, with holistic recycling of Fe, Al, and can be generically applied to any composition of red mud.