Kaolinite clay as a raw material for erbium extraction

Area of Science:

• Metallurgy and Materials Science
• Geochemistry
• Chemical Engineering

Background:

• The rare-earth industry's rapid growth necessitates new raw material sources and extraction technologies.
• Rare-earth metals (REM), primarily erbium (Er), are found in kaolinite clays from deposits in Kazakhstan and Egypt.
• Erbium concentrate production is a potential by-product of alumina and building material processing from kaolinite clays.

Purpose of the Study:

• To determine the feasibility of producing erbium concentrate from kaolinite clays.
• To optimize the technological conditions for sulfuric acid leaching and sorption concentration of REM.
• To evaluate the efficiency of separating REM from major clay components.

Main Methods:

• Sulfuric acid leaching of kaolinite clays under optimized conditions (5% H2SO4, 50°C, 60 min, L:S ratio of 5).
• Sorption concentration to isolate and enrich rare-earth elements.
• Chemical analysis to determine the composition of concentrates, including REM oxides and erbium content.

Main Results:

• Optimal leaching conditions were identified, enabling effective separation of REM from Fe2O3, Al2O3, and SiO2.
• Concentrates with a total REM oxide content ranging from 91.3% to 93.4% were obtained.
• The relative content of erbium within the REM sum ranged from 64.89% to 90.82%.

Conclusions:

• The developed technology is effective for processing kaolinite clays containing rare-earth metals, particularly erbium.
• This method offers a viable route for producing high-purity erbium concentrate as a by-product.
• The technology is applicable to various deposits of erbium-containing kaolinite clays.