Nitric Acid Leaching for Magnesium Extraction from Asbestos Ore Waste: From DoE to Predictive Modeling and...

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Kazakhstan's asbestos industry generates over 3 million tons of annual waste, primarily magnesium-rich minerals.
• Efficiently extracting valuable resources from industrial waste is crucial for sustainability and economic viability.

Purpose of the Study:

• To systematically investigate and optimize the extraction of magnesium from asbestos ore waste (AOW) using nitric acid (HNO3).
• To maximize magnesium extraction efficiency and cost-effectiveness while exploring a closed-cycle process.

Main Methods:

• Experimental optimization of nitric acid concentration, leaching temperature, time, solid-to-liquid ratio, and particle size.
• Application of the Protodyakonov model to validate extraction rate dependencies.
• Analysis of magnesium nitrate decomposition for closed-cycle process potential.

Main Results:

• Magnesium extraction efficiency is most dependent on acid concentration, followed by temperature, time, and solid-to-liquid ratio; particle size was negligible.
• Optimal cost-efficiency achieved with acid concentrations < 450 g/L and temperatures between 65-85 °C.
• Extraction efficiencies up to 90% are attainable, reducing reagent use and production costs.

Conclusions:

• Nitric acid leaching is an effective method for magnesium extraction from AOW.
• The process enables a closed-cycle system through magnesium nitrate decomposition, allowing HNO3 regeneration.
• This approach offers a sustainable and cost-effective pathway for magnesium production from industrial waste.