Characterization and atmospheric hydrochloric acid leaching of a limonitic laterite from Indonesia

The characterization and atmospheric hydrochloric acid leaching of a limonitic laterite from Indonesia were investigated in the current paper. The mineral and chemical compositions of the laterite were studied by X-ray diffraction (XRD) analysis, optical microscopy, scanning electron microscopy/X-ray energy dispersive spectroscopy (SEM/EDS), carbon/sulfur (C–S) analysis, and Fe(II) content titration. The laterite mainly contained goethite, siderite (~ 16.6 wt.%), chrysotile, and magnetite (~ 14.6 wt.%); Ni was incorporated in all major minerals. Complete leaching of the host minerals in hydrochloric acid was investigated, given that economical regeneration of the acid by hydrolysis was possible. Atmospheric leaching experiments were carried out to investigate the effect of acid–ore ratio (a/o), liquid–solid ratio (l/s), leaching temperature and time on the leach recovery of Ni (95.1%), Co (99.0%), and Fe (94.6%). Siderite and chrysotile in the ore were highly leachable; goethite dissolved in a wide range of a/o; magnetite and maghemite were moderately active.