Metal Extraction By-products
When producing magnesium from fly ash, Latrobe Magnesium Limited (LMG) extracts minerals first so they do not go through the magnesium process. Following this, a range of products are blended into a feedstock for its smelter. The beneficiated fly ash may only represent some 35% of the feedstock. The smelter is heated to 1,200 degrees Celsius and the magnesium is vacuumed into a magnesium crown. The residual product is what LMG describes as its Supplementary Cementitious Material (SCM).
The SCM has the same chemistry as Portland Cement. Its mineralogy is mainly in a belite form with some alite form present. The material is traditionally very fine with more than 75% being under 45 microns.
Test work has shown that the early hydration of this material is due to the fineness of the SCM.
Application and Uses
LMG’s SCM is eco-friendly as it doesn't generate CO2 emissions during the making of the product.
Tests have been conducted using varying percentages of the SCM. When compared to a control mix of Portland Cement and a mix with 25% black coal fly ash and Portland Cement, It was determined that using 30% of LMG’s SCM with Portland Cement was the optimum amount.
The SCM showed better performance than traditional black coal fly ash. Contributing to this was the strength and set time being performed within a seven day period versus a 28 day period.