Effective and economical treatment of low-grade nickel laterite by a duplex process of direct reduction-magnetic separation & rotary kiln-electric furnace and its industrial application

An innovative technical route has been proposed to improve recycling efficiency of Ni and Fe from low-grade nickel laterite via the duplex process between direct reduction-magnetic separation and rotary kiln-electric furnace. The results indicated that the high‑nickel concentrates produced from direct reduction-magnetic separation process, which were combined with optimization of slag types can not only increase the grade of furnace burdens and decrease quantity of slag, but also improve the fluidity of slag and smelting efficiency as well as reduce the power consumption of smelting. For the industrial application of duplex process, a preferable stainless-steel master alloy with 10.02% Ni was obtained at a lower cost of 8420 RMB/t than that of 8731 RMB/t for a stainless-steel master alloy containing 8.14% Ni in conventional rotary kiln-electric furnace process, and the recovery of nickel also increased from 91.27% to 95.51%, which shows an obvious superiority for treating the low-grade nickel laterite. [Display omitted] •An effective and economical way for processing low-grade nickel laterite was proposed.•The strengthening mechanism of DRMS-RKEF for recycling Ni and Fe was revealed.•The performance and prospect of DRMS-RKEF into industrial application were clarified.