Experimental investigation of continuous magnesium production by carbothermal reduction

Abstract

Magnesium production by carbothermal reduction (CTR) has the potential to significantly reduce operational and capital costs relative to reduction by ferrosilicon or electrolysis of magnesium chloride. As magnesium is gaseous at CTR temperatures the challenge remains in the effective separation of magnesium vapor and CO by-product, which can recombine unproductively. Our initial investigations focused on CTR kinetics and magnesium yield in batch reactions at isothermal and isobaric conditions. Further experimentation simulated continuous production; magnesium metal was boiled in a thermogravimetric system and mixed with CO in a tubular condenser. Monitoring of the CO signal by nondispersive infrared absorption (NDIR) allowed for determination of the extent of reversion, and analysis of deposits revealed the purity of the product Mg. The effect of pressure and temperature were investigated in both systems. Based on these results a continuous moving bed condenser was fabricated to determine the feasibility of vapor product capture from CTR.