Engineering Assessment of Niobium Recovery Potential from TiCl4 Wet Scrubber Slurry: Material and Heat Balances, Thermal-Separation Design, and Techno-Economic Screening

Abstract

Niobium can concentrate in TiCl4 wet scrubber slurry during molten-salt chlorination of ilmenite-derived titanium slag. This study presents an engineering assessment using published Nb-routing data, characterization of an isolated slurry solid, HSC Chemistry 6 balances, process design, and techno-economic screening. The reference model combines a 58.2% slag-to-slurry Nb distribution with an independently published bulk grade of 11.6841 wt.% Nb. These inputs come from different datasets and define a scenario rather than a closed campaign balance. For slag containing 0.044 wt.% Nb2O5, the calculated slurry inventory is 0.179 kg Nb t−1 slag and dry-intermediate yield 1.53 kg t−1 slag. XRD and SEM–EDS characterize a heterogeneous isolated solid with local Nb-rich domains; laboratory preparation did not reproduce the proposed two-stage treatment. With complete assumed Nb retention, the upper-bound routing/recovery potential is 58.1%; 95% and 90% thermal-retention cases reduce it to 55.2% and 52.3%. The theoretical process-material duty is 8.02 MJ t−1 slag and heating electricity 2.51 kWh t−1 slag. At 30,000 t slag y−1, screening CAPEX is USD 0.293 million and annualized thermal-section cost USD 2.34 t−1 slag. Pilot testing is required to close the Nb balance and verify energy use and condensate composition before recovery or recycle performance can be demonstrated.