Characterisation and beneficiation of zircon-rich heavy mineral concentrates from central Kalimantan (Borneo, Indonesia)

Abstract

Central Kalimantan is an emerging and potentially significant zircon and heavy mineral (HM) province. Characterisation and beneficiation testwork was conducted on two HM alluvial tailings and two zircon-rich concentrates sourced from artisanal production in the Sampit region in Central Kalimantan. The HM assemblage in all samples was dominated by a zircon-rich component. A premium grade zircon product (>66%ZrO2+HfO2 and U+Th<500 ppm) was produced by employing standard electrostatic and magnetic separation procedures. An ilmenite-rich fraction (∼59%TiO2) containing minor rutile and leucoxene was also successfully produced as a coproduct. Problem impurities in the ilmenite-rich fraction included significant levels (2˙55%) of chromia (Cr2O3) which was concentrated in discrete chrome-bearing spinels. Implications of the mineralogy and chemistry of this fraction for future processing are discussed. No attempt was made to recover the rutile and leucoxene.