From Nickel Ore to Ni Nanoparticles in the Extraction Process: Properties and Application

Laterite nickel ore is a mineral rock, which contains iron–nickel oxide compounds. One processing technology proposed to treat the ore is the Caron process. In general, the Caron process combines pyrometallurgical and hydrometallurgical stages. In the pyrometallurgical step, the ore mixed with reductant is heated up to 1800 °C in a rotary kiln-electric furnace to transform iron–nickel oxide into iron–nickel alloy. In the hydrometallurgical stage, nickel has to be dissolved selectively using ammonia solution (alkaline). The further process is aimed to separate and purify the nickel in ammonia solution using solvent extraction and precipitation. The disadvantages of the pyrometallurgical stage in the Caron process include high-energy consumption, low economic value, and technical problems such as partially melted material, which hinders the further process. While in the hydrometallurgical stage, the extensive use of ammonia causes an environmental impact. Selective reduction is proposed to solve problems in the pyrometallurgical stage. Selective reduction is a process favouring the formation of iron oxide to obtain high nickel content in an intermediate product with less energy consumption. An additive is added to the ore to reduce selectively the nickel and decrease the reaction temperature. To solve the environmental impact of ammonia, a novel and safer chemical is proposed as a substitute — the monosodium glutamate (MSG). Selective reduction combined with alkaline leaching using MSG is proposed as an alternative to the Caron method. Precipitation is employed further to purify the nickel that results in nickel nanoparticles with 90–95 wt.% purity.