Effect of the Properties of Agglomerates Prepared by Geopolymerization on Column Bioleaching

Agglomeration of fine particles to produce agglomerates with desired properties (e.g., size distribution, internal pores, and stability) is a critically important precursor to heap leaching. In this work, the effect of the properties of agglomerates prepared by geopolymerization on column bioleaching was investigated. The agglomerates were prepared with different metakaolin addition and alkali activator composition. Reducing the metakaolin addition and increasing the sodium silicate content in the alkali activator was beneficial to increasing agglomerate size. With the increase of agglomerate size, size distribution uniformity also improved. NMR analysis showed that agglomerates prepared with minor metakaolin addition and alkali activator composed of fewer Na₂SiO₃ had more and larger pores. Column bioleaching experiments showed that the agglomerates with more and larger pores had lower permeability and higher copper extraction. For more efficient leaching, the added alkali activator did not need to contain NaOH. This study’s results can guide the agglomeration operation based on geopolymerization to prepare agglomerates that better meet the requirements of heap leaching.