ADVANCES IN KAOLIN BENEFICIATION FOR CERAMIC APPLICATIONS: PROCESSING STRATEGIES, PROPERTY ENHANCEMENT, AND INDUSTRIAL IMPLICATIONS

Abstract

Natural kaolin rarely meets the chemical, optical, particle-size and firing requirements of high-value ceramics without upgrading. This structured narrative review evaluates physical, chemical, biological, thermal and hybrid beneficiation routes, with particular attention to African deposits and the transfer of laboratory findings to ceramic production. The evidence audit covered publications from 2010 to September 2026, nine earlier foundational sources and relevant ceramic standards. It assembled 100 candidate records, screened 85 unique records and retained 57 documents. Results varied strongly by deposit. For Ethiopian kaolin, sequential beneficiation and oxalic-acid leaching lowered Fe₂O₃ from 2.40 to 0.36 wt%, an 85% reduction, and raised ISO whiteness from 72.0 to 81.4. The increase was 9.4 absolute ISO points or 13.1% relative to the starting value, while the treated sample remained below the commercial comparator value of 88.14. A separate route combining pre-agitation, high-pressure washing and oxalic-acid leaching reduced iron from 9.75 wt% to below 1 wt%, although it rejected up to 20% of the feed. Confidence in cross-deposit transfer was generally moderate because many experiments omitted replicate uncertainty, complete mass balances or ceramic-product validation. The evidence supports staged processing in which physical rejection of liberated impurities precedes selective leaching of accessible residual iron. Water and reagents should be recovered, and calcination should be reserved for products that require phase modification. Research priorities are standardized property reporting, dispersion control after leaching, pilot-scale mass and energy balances, residue utilization and deposit-specific predictive models. Proposed pilot targets are at least 90% wash-water reuse, 80% reagent recovery and a 30% reduction in thermal energy relative to the measured local baseline.