Facile, Low-Energy Routes for the Production of Hydrated Calcium and Magnesium Salts from Alkaline Industrial Wastes

Summary

UCLA researchers in the Department of Civil and Environment Engineering have developed a method for production of hydrated calcium and magnesium salts from alkaline industrial wastes using a facile and low-energy process.

Background

The commercial production of Ca(OH)₂ (portlandite) and Mg(OH)₂ (brucite) presently involves calcining based methods, which require a significant amount of thermal energy. The production process is relatively complicated, involving high temperature calcination (around 800°C for Ca(OH)₂ and 1000 °C for Mg(OH)₂).

Innovation

UCLA researchers have developed a novel method for Ca(OH)₂ and Mg(OH)₂ production which can be performed entirely at temperatures below 100°C. The process involves (1) extracting Ca and Mg ions from crystalline and amorphous alkaline solids via leaching and/or dissolution, (2) concentration of Ca and Mg in the leachate via capacitive concentration and reverse osmosis membrane filtration methods, and (3) precipitation of Ca(OH)₂ and Mg(OH)₂ from solution via low temperature heating. The process utilizes industrial waste streams, including those from metal processing and fuel combustion (e.g., coal ash) as raw materials, as well as waste heat from power plants for precipitation. In addition, the capacitive concentration method may be highly selective to divalent ions, achieving even higher extents of concentration during the process.

Applications

• Hydrated calcium and magnesium salt production
• Concentration of divalent ions
• Industrial waste utilization

Advantages

• Utilization of industrial waste, cost-effective and sustainable 
• High concentration yield 
• Facile process 
• Low energy consumption

Patent Status